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The Latest Security Topics

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AngularJS: How to Handle XSS Vulnerability Scenarios
this article represents different scenarios related with xss (cross-site scripting) and how to handle them appropriately using angularjs features such as sce ($sceprovider) and sanitize service ($sanitizeprovider) . please feel free to comment/suggest if i missed to mention one or more important points. also, sorry for the typos. following are the key xss-related scenarios described later in this article: escape html completely insert html in secure way while ignoring elements such as “script”. this is as well dangerous and could deface your website, if not taken care, especially with “img” tag. trust and insert entire html; this is dangerous and could easily end-up defacing your website escape html using ng-bind directive in case you want to escape html in entireity, you may want to use ng-bind directive. all it does is escape the html elements and print it as it is. following code demonstrates the ng-bind directive usage. angularjs xss demo test ng-bind directive: note that html text is entered as it is. {{hellomessage} following diagram demonstrates the above. pay attention to the html code entered in the text field. it is printed as it is, on to the html page. insert html in secure way, while ignoring elements such as “script”, using ng-bind-html directive this is key to solving xss attacks. that said, one should still take care of elements such as “img” ( included as part of white-list; void elements) as it could display any image (including illegal ones) on your webpage, thus, defacing your webpage . using ng-bind-html directive, javascript script tag such as “script” could be ignored straight-away. ng-bind-html directive evaluates the expression and inserts the resulting html into the element in a secure way. for cases where user inputs could consist of html (such as comments), the inclusion of ng-bind-html directive would ensure that the text is sanitize against a white-list of safe html tokens. the whitelist of safe tokens is coded as part of $sanitize module and mentioned below. following is included in the safe list (taken directly from the source code): void elements : area,br,col,hr,img,wbr. the details of same could be found at http://dev.w3.org/html5/spec/overview.html#void-elements block element : address,article,aside,blockquote,caption,center,del,dir,div,dl,figure,figcaption,footer,h1,h2,h3,h4, h5,h6,header,hgroup,hr,ins,map,menu,nav,ol,pre,script,section,table,ul inline elements : a,abbr,acronym,b,bdi,bdo,big,br,cite,code,del,dfn,em,font,i,img,ins,kbd,label,map,mark,q,ruby, rp,rt,s,samp,small,span,strike,strong,sub,sup,time,tt,u,var end tag elements : colgroup,dd,dt,li,p,tbody,td,tfoot,th,thead,tr,rp,rt. the details of same could be found at http://dev.w3.org/html5/spec/overview.html#optional-tags following are two elements which are escaped as it is in untrusted category . in case, you want to show it, you would have to use $sce service and call trustashtml method for angular to execute below-mentioned elements. script style following represents code sample demonstrating the ng-bind-html directive usage. angularjs xss demo test ng-bind-html directive: note that image is displayed appropriately as a result of text entered in the text field. following image demonstrates how it looks like when entering html code in textfield that is inserted into dom in a secure way. pay attention to “img” element which is a part of void elements in above list. as the code is entered in the textfield, the image appeared as “img” is in trusted list (white-list) trust and insert entire html warning: this is dangerous and could easily end-up defacing your website . only when you know and are doubly sure, you should use trustashtml. in case, you are confident that the text content could be trusted, you could use $sce service and call trustashtml method which then inserts entire html into the dom. pay attention to the html and javascript code snippet where $sce service is used to invoke trustashtml method to trust the html code. in that case, one code such as “” is inserted, it ended up painting already existing html element. this may not be healthy. one could change the background images with illegal images that way. ng-bind directive: note that html text is entered as it is. {{hellomessage} note that script tag is executed as well. following image demonstrates how it looks like when entering html style code in textfield that is inserted into dom . as a result, the other html element is painted in red as shown below. in scenarios where a hacker could insert an style element with background, this could show-up unwanted background and bring bad experience for the end users. entire code – cut/copy and paste and play angularjs xss demo test ng-bind directive: note that html text is entered as it is. {{hellomessage} note that script tag is executed as well. ng-bind-html directive: note that image is displayed appropriately as a result of text entered in the text field.
November 30, 2014
by Ajitesh Kumar
· 66,851 Views
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AngularJS - Top 6 Concepts that Developers Loved
this article represents top 6 popular angularjs topics that has been used most by the angularjs developer community to date. the inference is derived based on number of tagged discussions happening on stackoverflow . clearly, “directive” is the winner and attracts most of them all. the article presents my thoughts on why these topics have been most popular. please feel free to comment/suggest if i missed to mention one or more important points. also, sorry for the typos. following is the list of top 6 popular topics: directives scope object ng-repeat angular ui & bootstrap routing service following plot demonstrates the popularity of different feature/topics in relation with angularjs. angularjs topics popularity inference : some of the following could as well be inferred from the above data/plot. three features which have been most used by the developers and therefore, should be key reasons why you would also want to use angular in next project are following: directives routing ng-repeat one of the pain point (or shortcoming) that have been talked most by the angular developers is the ui widgets related support by angular. this is where most of them have jumped to angular ui and bootstrap. the topic/concept that has intrigued most to several developers is scope object. thoughts on why these topics may be most popular following are top 6 popular topics in angularjs discussed on forums such as stackoverflow: directives : this is, no doubt, the most popular and powerful feature of angularjs directives as also indicated by count of discussion threads posted on stackoverflow as of today. the power of directives lies in the following and this is why it is the most popular topic of angularjs. re-usability : once created a directive as part of a module, all that one need to do to use the directive is include the module as a dependency when defining new module and define the directives wherever required on the page. usability : owing to the fact that one could give intuitive names to directives, directive enhances the readability and understandability of code by a notch. greater adherence to dry principle : the aspect of templating makes directive a very attractive feature. it does reduce the duplication of code as same html template code could be used at several places without the need to write the code in html file. scope object : this is second most popular topic found based on the discussion count. rightfully expected as well! the whole notion of scope object and how it is key to dependency injection makes it one of the most powerful as well as tricky concept of angularjs. also, this is one of the topic which raised the barrier to entry for angularjs and contributed in making steep learning curve for developers. that said, scope is going to r.i.p in angular 2.0 which could be seen as a good sign for those who always struggled with scope object. ng-repeat : the ng-repeat feature brings power to angularjs from the fact that it is one of the feature that removed the need of server-side code required to repeat the html code over multiple iterations. with ng-repeat, one could easily repeat html code multiple times. angular ui & bootstrap : one of the shortcoming of angularjs for good or bad is its inability to be one and all solution to create some great ui along with powerful eventing feature. for creating fancy or great looking ui, one would still have to go to ui frameworks such as bootstrap, kendo-ui etc. this is where people have been looking for angularui and bootstrap. angularui comes with attractive feature set for enhanced routing, grid util, angularjs code editor plugins, bootstrap module etc. routing : routing feature is key to creating single page application. one of key reason why angularjs is very popular is the ease with which one could create single-page application using it. and, routing feature makes it all happen. no doubt, this is why many developers have been looking for it. service : service feature helps one to create reusable components in an angular module. these services could then be injected in another modules using dependency injection feature. the service could be injected in one of the following components: controllers services doing a quick recap, one may recall that for creating a service, one could use factory recipe method and define service that way. you could know details about creating a custom service on our another page dedicated on this.
November 29, 2014
by Ajitesh Kumar
· 35,132 Views · 1 Like
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Gradle Goodness: Check Task Dependencies With a Dry Run
We can run a Gradle build without any of the task actions being executed. This is a so-called dry run of our build. We can use the dry run of a build to see if the task dependencies we have defined or are defined in a plugin are defined properly. Because all tasks and task dependencies are resolved if we use the dry run mode we can see in the output which tasks are executed. We define a simple build file with three tasks and some task dependencies: def printTaskNameAction = { println "Running ${it.name}" } task first << printTaskNameAction task second(dependsOn: first) << printTaskNameAction task third(dependsOn: [first, second]) << printTaskNameAction To run a Gradle build as a dry run we can use the command line option -m or --dry-run. So let's execute the task third with the dry run command line option: $ gradle -m third :first SKIPPED :second SKIPPED :third SKIPPED BUILD SUCCESSFUL Total time: 2.242 secs $ And we see in the output none of the tasks are really executed, because SKIPPED is shown, but we do see the task names of the tasks that are resolved. Written with Gradle 2.2.
November 19, 2014
by Hubert Klein Ikkink
· 8,030 Views
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Spring @Configuration and Injecting Bean Dependencies as Method Parameters
One of the ways Spring recommends injecting inter-dependencies between beans is shown in the following sample copied from the Spring's reference guide here: @Configuration public class AppConfig { @Bean public Foo foo() { return new Foo(bar()); } @Bean public Bar bar() { return new Bar("bar1"); } } So here, bean `foo` is being injected with a `bar` dependency. However, there is one alternate way to inject dependency that is not documented well, it is to just take the dependency as a `@Bean` method parameter this way: @Configuration public class AppConfig { @Bean public Foo foo(Bar bar) { return new Foo(bar); } @Bean public Bar bar() { return new Bar("bar1"); } } There is a catch here though, the injection is now by type, the `bar` dependency would be resolved by type first and if duplicates are found, then by name: @Configuration public static class AppConfig { @Bean public Foo foo(Bar bar1) { return new Foo(bar1); } @Bean public Bar bar1() { return new Bar("bar1"); } @Bean public Bar bar2() { return new Bar("bar2"); } } In the above sample dependency `bar1` will be correctly injected. If you want to be more explicit about it, an @Qualifer annotation can be added in: @Configuration public class AppConfig { @Bean public Foo foo(@Qualifier("bar1") Bar bar1) { return new Foo(bar1); } @Bean public Bar bar1() { return new Bar("bar1"); } @Bean public Bar bar2() { return new Bar("bar2"); } } So now the question of whether this is recommended at all, I would say yes for certain cases. For eg, had the bar bean been defined in a different @Configuration class , the way to inject the dependency then is along these lines: @Configuration public class AppConfig { @Autowired @Qualifier("bar1") private Bar bar1; @Bean public Foo foo() { return new Foo(bar1); } } I find the method parameter approach simpler here: @Configuration public class AppConfig { @Bean public Foo foo(@Qualifier("bar1") Bar bar1) { return new Foo(bar1); } }
October 14, 2014
by Biju Kunjummen
· 126,644 Views · 20 Likes
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Creating Executable Uber Jar’s and Native Applications with Java 8 and Maven
creating uber jar’s in java is nothing particular new, even creating executable jar’s was possible with maven long before java 8. with the first release of javafx 2, oracle introduced the javafxpackager tool, which has now been renamed to javapackager (java 8 u20). this enables developers to create native executables for any common platform, even mac app store packages; the drawbacks of the javapackager are that you must create the executable on the target platform and that it will than contain the whole jre to run the application. this means that your 100kb application gets more than 40mb, depending on your target platform. the first step on your way to an executable uber jar is to build your project and to collect all dependencies in a folder or a fat jar. this folder/fat jar will be the input for the javapackager tool, which creates the executable part. solution 1: the maven-dependency-plugin the maven-dependency-plugin contains the goal “unpack-dependencies”. we can use this goal to enhance the default “target/classes” folder with all the dependencies you need to run your application. we assume that the default maven build creates all classes of your project in the “target/classes” folder and the “unpack-dependencies” plugin copies all the project dependencies to this folder. the result is a valid input for the javapackager tool, which creates the executable. the “unpack-dependencies” goal is easy to use; you just need to set the output directory to the “target/classes” folder to ensure everything is together in one folder. a typical configuration looks like this: maven-dependency-plugin 2.6 unpack-dependencies package unpack-dependencies system org.springframework.jmx ${project.build.directory}/classes to create an executable jar from the target/classes directory we use the “exec-maven-plugin” to execute the javapackager commandline tool. org.codehaus.mojo exec-maven-plugin package-jar package exec ${env.java_home}/bin/javapackager -createjar -appclass ${app.main.class} -srcdir ${project.build.directory}/classes -outdir ./target -outfile ${project.artifactid}-app -v now we can create an executable jar, which contains all the project dependencies and that can simply be executed with “java –jar myapp.jar”. in the next step we want to create a native executable or an installer. specific configuration details for the javapackager can be found here: http://docs.oracle.com/javase/8/docs/technotes/tools/unix/javapackager.html , for this tutorial we assume that we want to create a native installer. to do so, we add a second “execution” to your “exec-maven-plugin” like this: package-jar2 package exec ${env.java_home}/bin/javapackager -deploy -native installer -appclass ${app.main.class} -srcfiles ${project.build.directory}/${artifactid}-app.jar -outdir ./target -outfile ${project.artifactid}-app -v once the configuration is done, you can run “mvn clean package” and you will find your executable jar as well as the native installer in your target folder. this solution works fine in most cases, but sometimes you can get in trouble with this plugin. when you have configuration files in your project that also exist in one of your dependencies, the unpack-dependency goal will overwrite your configuration file. for example your project contains a file like “meta-inf/service/com.myconf.file” and any dependency does contain the same file. in this case solution 2 may be a better approach. solution 2: the maven-shade plugin the maven-shade plugin provides the capability to package artifacts into an uber-jar, including its dependencies. it also provides various transformers to merge configuration files or to define the manifest of your jar file. this capability allows us to create an executable uber jar without involving the javapackager, so the packager is only needed to create the native executable. to build an executable uber jar following plugin configuration is needed: org.apache.maven.plugins maven-shade-plugin 2.3 package shade junit:junit jmock:* *:xml-apis … meta-inf/services/conf.file ${app.main.class} ${maven.compile.java.version} ${maven.compile.java.version} this configuration defines a main-class entry in the manifest and merges all “meta-inf/services/conf.files” together. the resulting executable jar file is now a valid input for the javapacker to create a native installer. the configuration to create a native installer with “exec-maven-plugin” and javapacker tool is exactly the same like in solution 1. i provided two example projects on github https://github.com/amoahcp/mvndemos where you can test both configurations. these are two simple projects with a main class starting a jetty webserver on port 8080, so the only dependency is jetty. both solutions can be used for any type of java projects, even with swing or javafx. reference: http://jacpfx.org/2014/10/08/uber-jars.html
October 12, 2014
by Andy Moncsek
· 29,451 Views
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Embedded Jetty and Apache CXF: Secure REST Services With Spring Security
Recently I ran into very interesting problem which I thought would take me just a couple of minutes to solve: protecting Apache CXF (current release 3.0.1)/ JAX-RS REST services with Spring Security (current stable version 3.2.5) in the application running inside embedded Jetty container (current release 9.2). At the end, it turns out to be very easy, once you understand how things work together and known subtle intrinsic details. This blog post will try to reveal that. Our example application is going to expose a simple JAX-RS / REST service to manage people. However, we do not want everyone to be allowed to do that so the HTTP basic authentication will be required in order to access our endpoint, deployed at http://localhost:8080/api/rest/people. Let us take a look on thePeopleRestService class: package com.example.rs; import javax.json.Json; import javax.json.JsonArray; import javax.ws.rs.GET; import javax.ws.rs.Path; import javax.ws.rs.Produces; @Path( "/people" ) public class PeopleRestService { @Produces( { "application/json" } ) @GET public JsonArray getPeople() { return Json.createArrayBuilder() .add( Json.createObjectBuilder() .add( "firstName", "Tom" ) .add( "lastName", "Tommyknocker" ) .add( "email", "[email protected]" ) ) .build(); } } As you can see in the snippet above, nothing is pointing out to the fact that this REST service is secured, just couple of familiar JAX-RS annotations. Now, let us declare the desired security configuration following excellent Spring Security documentation. There are many ways to configure Spring Security but we are going to show off two of them: using in-memory authentication and using user details service, both built on top of WebSecurityConfigurerAdapter. Let us start with in-memory authentication as it is the simplest one: package com.example.config; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.context.annotation.Configuration; import org.springframework.security.config.annotation.authentication.builders.AuthenticationManagerBuilder; import org.springframework.security.config.annotation.method.configuration.EnableGlobalMethodSecurity; import org.springframework.security.config.annotation.web.builders.HttpSecurity; import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity; import org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter; import org.springframework.security.config.http.SessionCreationPolicy; @Configuration @EnableWebSecurity @EnableGlobalMethodSecurity( securedEnabled = true ) public class InMemorySecurityConfig extends WebSecurityConfigurerAdapter { @Autowired public void configureGlobal(AuthenticationManagerBuilder auth) throws Exception { auth.inMemoryAuthentication() .withUser( "user" ).password( "password" ).roles( "USER" ).and() .withUser( "admin" ).password( "password" ).roles( "USER", "ADMIN" ); } @Override protected void configure( HttpSecurity http ) throws Exception { http.httpBasic().and() .sessionManagement().sessionCreationPolicy( SessionCreationPolicy.STATELESS ).and() .authorizeRequests().antMatchers("/**").hasRole( "USER" ); } } In the snippet above there two users defined: user with the role USER and admin with the roles USER,ADMIN. We also protecting all URLs (/**) by setting authorization policy to allow access only users with roleUSER. Being just a part of the application configuration, let us plug it into the AppConfig class using @Importannotation. package com.example.config; import java.util.Arrays; import javax.ws.rs.ext.RuntimeDelegate; import org.apache.cxf.bus.spring.SpringBus; import org.apache.cxf.endpoint.Server; import org.apache.cxf.jaxrs.JAXRSServerFactoryBean; import org.apache.cxf.jaxrs.provider.jsrjsonp.JsrJsonpProvider; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; import org.springframework.context.annotation.DependsOn; import org.springframework.context.annotation.Import; import com.example.rs.JaxRsApiApplication; import com.example.rs.PeopleRestService; @Configuration @Import( InMemorySecurityConfig.class ) public class AppConfig { @Bean( destroyMethod = "shutdown" ) public SpringBus cxf() { return new SpringBus(); } @Bean @DependsOn ( "cxf" ) public Server jaxRsServer() { JAXRSServerFactoryBean factory = RuntimeDelegate.getInstance().createEndpoint( jaxRsApiApplication(), JAXRSServerFactoryBean.class ); factory.setServiceBeans( Arrays.< Object >asList( peopleRestService() ) ); factory.setAddress( factory.getAddress() ); factory.setProviders( Arrays.< Object >asList( new JsrJsonpProvider() ) ); return factory.create(); } @Bean public JaxRsApiApplication jaxRsApiApplication() { return new JaxRsApiApplication(); } @Bean public PeopleRestService peopleRestService() { return new PeopleRestService(); } } At this point we have all the pieces except the most interesting one: the code which runs embedded Jettyinstance and creates proper servlet mappings, listeners, passing down the configuration we have created. package com.example; import java.util.EnumSet; import javax.servlet.DispatcherType; import org.apache.cxf.transport.servlet.CXFServlet; import org.eclipse.jetty.server.Server; import org.eclipse.jetty.servlet.FilterHolder; import org.eclipse.jetty.servlet.ServletContextHandler; import org.eclipse.jetty.servlet.ServletHolder; import org.springframework.web.context.ContextLoaderListener; import org.springframework.web.context.support.AnnotationConfigWebApplicationContext; import org.springframework.web.filter.DelegatingFilterProxy; import com.example.config.AppConfig; public class Starter { public static void main( final String[] args ) throws Exception { Server server = new Server( 8080 ); // Register and map the dispatcher servlet final ServletHolder servletHolder = new ServletHolder( new CXFServlet() ); final ServletContextHandler context = new ServletContextHandler(); context.setContextPath( "/" ); context.addServlet( servletHolder, "/rest/*" ); context.addEventListener( new ContextLoaderListener() ); context.setInitParameter( "contextClass", AnnotationConfigWebApplicationContext.class.getName() ); context.setInitParameter( "contextConfigLocation", AppConfig.class.getName() ); // Add Spring Security Filter by the name context.addFilter( new FilterHolder( new DelegatingFilterProxy( "springSecurityFilterChain" ) ), "/*", EnumSet.allOf( DispatcherType.class ) ); server.setHandler( context ); server.start(); server.join(); } } Most of the code does not require any explanation except the the filter part. This is what I meant by subtle intrinsic detail: the DelegatingFilterProxy should be configured with the filter name which must be exactlyspringSecurityFilterChain, as Spring Security names it. With that, the security rules we have configured are going to apply to any JAX-RS service call (the security filter is executed before the Apache CXF servlet), requiring the full authentication. Let us quickly check that by building and running the project: mvn clean package java -jar target/jax-rs-2.0-spring-security-0.0.1-SNAPSHOT.jar Issuing the HTTP GET call without providing username and password does not succeed and returns HTTP status code 401. > curl -i http://localhost:8080/rest/api/people HTTP/1.1 401 Full authentication is required to access this resource WWW-Authenticate: Basic realm="Realm" Cache-Control: must-revalidate,no-cache,no-store Content-Type: text/html; charset=ISO-8859-1 Content-Length: 339 Server: Jetty(9.2.2.v20140723) The same HTTP GET call with username and password provided returns successful response (with some JSON generated by the server). > curl -i -u user:password http://localhost:8080/rest/api/people HTTP/1.1 200 OK Date: Sun, 28 Sep 2014 20:07:35 GMT Content-Type: application/json Content-Length: 65 Server: Jetty(9.2.2.v20140723) [{"firstName":"Tom","lastName":"Tommyknocker","email":"[email protected]"}] Excellent, it works like a charm! Turns out, it is really very easy. Also, as it was mentioned before, the in-memory authentication could be replaced with user details service, here is an example how it could be done: package com.example.config; import java.util.Arrays; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; import org.springframework.security.config.annotation.authentication.builders.AuthenticationManagerBuilder; import org.springframework.security.config.annotation.method.configuration.EnableGlobalMethodSecurity; import org.springframework.security.config.annotation.web.builders.HttpSecurity; import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity; import org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter; import org.springframework.security.config.http.SessionCreationPolicy; import org.springframework.security.core.authority.SimpleGrantedAuthority; import org.springframework.security.core.userdetails.User; import org.springframework.security.core.userdetails.UserDetails; import org.springframework.security.core.userdetails.UserDetailsService; import org.springframework.security.core.userdetails.UsernameNotFoundException; @Configuration @EnableWebSecurity @EnableGlobalMethodSecurity(securedEnabled = true) public class UserDetailsSecurityConfig extends WebSecurityConfigurerAdapter { @Autowired public void configureGlobal(AuthenticationManagerBuilder auth) throws Exception { auth.userDetailsService( userDetailsService() ); } @Bean public UserDetailsService userDetailsService() { return new UserDetailsService() { @Override public UserDetails loadUserByUsername( final String username ) throws UsernameNotFoundException { if( username.equals( "admin" ) ) { return new User( username, "password", true, true, true, true, Arrays.asList( new SimpleGrantedAuthority( "ROLE_USER" ), new SimpleGrantedAuthority( "ROLE_ADMIN" ) ) ); } else if ( username.equals( "user" ) ) { return new User( username, "password", true, true, true, true, Arrays.asList( new SimpleGrantedAuthority( "ROLE_USER" ) ) ); } return null; } }; } @Override protected void configure( HttpSecurity http ) throws Exception { http .httpBasic().and() .sessionManagement().sessionCreationPolicy( SessionCreationPolicy.STATELESS ).and() .authorizeRequests().antMatchers("/**").hasRole( "USER" ); } } Replacing the @Import( InMemorySecurityConfig.class ) with @Import( UserDetailsSecurityConfig.class ) in the AppConfig class leads to the same results, as both security configurations define the identical sets of users and their roles. I hope, this blog post will save you some time and gives a good starting point, as Apache CXF and Spring Security are getting along very well under Jetty umbrella! The complete source code is available on GitHub.
September 30, 2014
by Andriy Redko
· 19,061 Views · 1 Like
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Can Static Analysis replace Code Reviews?
In my last post, I explained how to do code reviews properly. I recommended taking advantage of static analysis tools like Findbugs, PMD, Klocwork or Fortify to check for common mistakes and bad code before passing the code on to a reviewer, to make the reviewer’s job easier and reviews more effective. Some readers asked whether static analysis tools can be used instead of manual code reviews. Manual code reviews add delays and costs to development, while static analysis tools keep getting better, faster, and more accurate. So can you automate code reviews, in the same way that many teams automate functional testing? Do you need to do manual reviews too, or can you rely on technology to do the job for you? Let’s start by understanding what static analysis bug checking tools are good at, and what they aren’t. What static analysis tools can do – and what they can’t do In this article, Paul Anderson at GrammaTech does a good job of explaining how static analysis bug finding works, the trade-offs between recall (finding all of the real problems), precision (minimizing false positives) and speed, and the practical limitations of using static analysis tools for finding bugs. Static analysis tools are very good at catching certain kinds of mistakes, including memory corruption and buffer overflows (for C/C++), memory leaks, illegal and unsafe operations, null pointers, infinite loops, incomplete code, redundant code and dead code. A static analysis tool knows if you are calling a library incorrectly (as long as it recognizes the function), if you are using the language incorrectly (things that a compiler could find but doesn’t) or inconsistently (indicating that the programmer may have misunderstood something). And static analysis tools can identify code with maintainability problems, code that doesn't follow good practice or standards, is complex or badly structured and a good candidate for refactoring. But these tools can’t tell you when you have got the requirements wrong, or when you have forgotten something or missed something important – because the tool doesn't know what the code is supposed to do. A tool can find common off-by-one mistakes and some endless loops, but it won’t catch application logic mistakes like sorting in descending order instead of ascending order, or dividing when you meant to multiply, referring to buyer when it should have been seller, or lessee instead of lessor. These are mistakes that aren't going to be caught in unit testing either, since the same person who wrote the code wrote the tests, and will make the same mistakes. Tools can’t find missing functions or unimplemented features or checks that should have been made but weren't. They can’t find mistakes or holes in workflows. Or oversights in auditing or logging. Or debugging code left in by accident. Static analysis tools may be able to find some backdoors or trapdoors – simple ones at least. And they might find some concurrency problems – deadlocks, races and mistakes or inconsistencies in locking. But they will miss a lot of them too. Static analysis tools like Findbugs can do security checks for you: unsafe calls and operations, use of weak encryption algorithms and weak random numbers, using hard-coded passwords, and at least some cases of XSS, CSRF, and simple SQL injection. More advanced commercial tools that do inter-procedural and data flow analysis (looking at the sources, sinks and paths between) can find other bugs including injection problems that are difficult and time-consuming to trace by hand. But a tool can’t tell you that you forgot to encrypt an important piece of data, or that you shouldn't be storing some data in the first place. It can’t find logic bugs in critical security features, if sensitive information could be leaked, when you got an access control check wrong, or if the code could fail open instead of closed. And using one static analysis tool on its own to check code may not be enough. Evaluations of static analysis tools, such as NIST's SAMATE project (a series of comparative studies, where many tools are run against the same code), show almost no overlap between the problems found by different tools (outside of a few common areas like buffer errors) even when the tools are supposed to be doing the same kinds of checks. Which means that to get the most out of static analysis, you will need to run two or more tools against the same code (which is what SonarQube, for example, which integrates its own static analysis results with other tools, including popular free tools, does for you). If you’re paying for commercial tools, this could get very expensive fast. Tools vs. Manual Reviews Tools can find cases of bad coding or bad typing – but not bad thinking. These are problems that you will have to find through manual reviews. A 2005 study Comparing Bug Finding Tools with Reviews and Tests used Open Source bug finding tools (including Findbugs and PMD) on 5 different code bases, comparing what the tools found to what was found through code reviews and functional testing. Static analysis tools found only a small subset of the bugs found in manual reviews, although the tools were more consistent – manual reviewers missed a few cases that the tools picked up. Just like manual reviews, the tools found more problems with maintainability than real defects (this is partly because one of the tools evaluated – PMD – focuses on code structure and best practices). Testing (black box – including equivalence and boundary testing – and white box functional testing and unit testing) found fewer bugs than reviews. But different bugs. There was no overlap at all between bugs found in testing and the bugs found by the static analysis tools. Finding problems that could happen - or do happen Static analysis tools are good at finding problems that “could happen”, but not necessarily problems that “do happen”. Researchers at Colorado State University ran static analysis tools against several releases of different Open Source projects, and compared what the tools found against the changes and fixes that developers actually made over a period of a few years – to see whether the tools could correctly predict the fixes that needed to be made and what code needed to be refactored. The tools reported hundreds of problems in the code, but found very few of the serious problems that developers ended up fixing. One simple tool (Jlint) did not find anything that was actually fixed or cleaned up by developers. Of 112 serious bugs that were fixed in one project, only 3 were also found by static analysis tools. In another project, only 4 of 136 bugs that were actually reported and fixed were found by the tools. Many of the bugs that developers did fix were problems like null pointers and incorrect string operations – problems that static analysis tools should be good at catching, but didn’t. The tools did a much better job of predicting what code should be refactored: developers ended up refactoring and cleaning up more than 70% of the code structure and code clarity issues that the tools reported (PMD, a free code checking tool, was especially good for this). Ericsson evaluated different commercial static analysis tools against large, well-tested, mature applications. On one C application, a commercial tool found 40 defects – nothing that could cause a crash, but still problems that needed to be fixed. On another large C code base, 1% of the tool’s findings turned out to be bugs serious enough to fix. On the third project, they ran 2 commercial tools against an old version of a C system with known memory leaks. One tool found 32 bugs, another 16: only 3 of the bugs were found by both tools. Surprisingly, neither tool found the already known memory leaks – all of the bugs found were new ones. And on a Java system with known bugs they tried 3 different tools. None of the tools found any of the known bugs, but one of the tools found 19 new bugs that the team agreed to fix. Ericsson’s experience is that static analysis tools find bugs that are extremely difficult to find otherwise. But it’s rare to find stop-the-world bugs – especially in production code – using static analysis. This is backed up by another study on the use of static analysis (Findbugs) at Google and on the Sun JDK 1.6.0. Using the tool, engineers found a lot of bugs that were real, but not worth the cost of fixing: deliberate errors, masked errors, infeasible situations, code that was already doomed, errors in test code or logging code, errors in old code that was “going away soon” or other relatively unimportant cases. Only around 10% of medium and high priority correctness errors found by the tool were real bugs that absolutely needed to be fixed. The Case for Security So far we've mostly looked at static analysis checking for run-time correctness and general code quality, not security. Although security builds on code quality – vulnerabilities are just bugs that hackers look for and exploit – checking code for correctness and clarity isn’t enough for a secure app. A lot of investment in static analysis technology over the past 5-10 years has been in finding security problems in code, such as common problems listed in OWASP’s Top 10 or the SANS/CWE Top 25 Most Dangerous Software Errors. A couple of studies have looked at the effectiveness of static analysis tools compared to manual reviews in finding security vulnerabilities. The first study was on a large application that had 15 known security vulnerabilities found through a structured manual assessment done by security experts. Two different commercial static analysis tools were run across the code. The tools together found less than half of the known security bugs – only the simplest ones, the bugs that didn't require a deep understanding of the code or the design. And of course the tools reported thousands of other issues that needed to be reviewed and qualified or thrown away as false positives. These other issues including some run-time correctness problems, null pointers and resource leaks, and code quality findings (dead code, unused variables), but no other real security vulnerabilities beyond those already found by the manual security review. But this assumes that you have a security expert around to review the code. To find security vulnerabilities, a reviewer needs to understand the code (the language and the frameworks), and they also need to understand what kind of security problems to look for. Another study shows how difficult this is. Thirty developers were hired to do independent security code reviews of a small web app (some security experts, others web developers). They were not allowed to use static analysis tools. The app had 6 known vulnerabilities. 20% of the reviewers did not find any of the known bugs. None of the reviewers found all of the known bugs, although several found a new XSS vulnerability that the researchers hadn’t known about. On average, 10 reviewers would have had only an 80% chance of finding all of the security bugs. And, not Or Static analysis tools are especially useful for developers working in unsafe languages like C/C++ (where there is a wide choice of tools to find common mistakes) or dynamically typed scripting languages like Javascript or PHP (where unfortunately the tools aren't that good), and for teams starting off learning a new language and framework. Using static analysis is (or should be) a requirement in highly regulated, safety critical environments like medical devices and avionics. And until more developers get more training and understand more about how to write secure software, we will all need to lean on static analysis (and dynamic analysis) security testing tools to catch vulnerabilities. But static analysis isn't a substitute for code reviews. Yes, code reviews take extra time and add costs to development, even if you are smart about how you do them – and being smart includes running static analysis checks before you do reviews. If you want to move fast and write good, high-quality and secure code, you still have to do reviews.You can’t rely on static analysis alone.
September 29, 2014
by Jim Bird
· 15,072 Views
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How to Resolve Maven's ''Failure to Transfer'' Error
Learn how to resolve the ''failure to transfer'' error encountered in Maven in this quick tutorial.
September 24, 2014
by Jose Roy Javelosa
· 130,281 Views · 4 Likes
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Java - Four Security Vulnerabilities Related Coding Practices to Avoid
This article represents top 4 security vulnerabilities related coding practice to avoid while you are programming with Java language. Recently, I came across few Java projects where these instances were found. Please feel free to comment/suggest if I missed to mention one or more important points. Also, sorry for the typos. Following are the key points described later in this article: Executing a dynamically generated SQL statement Directly writing an Http Parameter to Servlet output Creating an SQL PreparedStatement from dynamic string Array is stored directly Executing a Dynamically Generated SQL Statement This is most common of all. One can find mention of this vulenrability at several places. As a matter of fact, many developers are also aware of this vulnerability, although this is a different thing they end up making mistakes once in a while. In several DAO classes, the instances such as following code were found which could lead to SQL injection attacks. StringBuilder query = new StringBuilder(); query.append( "select * from user u where u.name in (" + namesString + ")" ); try { Connection connection = getConnection(); Statement statement = connection.createStatement(); resultSet = statement.executeQuery(query.toString()); } Instead of above query, one could as well make use of prepared statement such as that demonstrated in the code below. It not only makes code less vulnerable to SQL injection attacks but also makes it more efficient. StringBuilder query = new StringBuilder(); query.append( "select * from user u where u.name in (?)" ); try { Connection connection = getConnection(); PreparedStatement statement = connection.prepareCall(query.toString()); statement.setString( 1, namesString ); resultSet = statement.execute(); } Directly writing an Http Parameter to Servlet Output In Servlet classes, I found instances where the Http request parameter was written as it is, to the output stream, without any validation checks. Following code demonstrate the same: public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String content = request.getParameter("some_param"); // // .... some code goes here // response.getWriter().print(content); } Note that above code does not persist anything. Code like above may lead to what is called reflected (or non-persistent) cross site scripting (XSS) vulnerability. Reflected XSS occur when an attacker injects browser executable code within a single HTTP response. As it goes by definition (being non-persistent), the injected attack does not get stored within the application; it manifests only users who open a maliciously crafted link or third-party web page. The attack string is included as part of the crafted URI or HTTP parameters, improperly processed by the application, and returned to the victim. You could read greater details on following OWASP page on reflect XSS Creating an SQL PreparedStatement from Dynamic Query String What it essentially means is the fact that although PreparedStatement was used, but the query was generated as a string buffer and not in the way recommended for prepared statement (parametrized). If unchecked, tainted data from a user would create a String where SQL injection could make it behave in unexpected and undesirable manner. One should rather make the query statement parametrized and, use the PreparedStatement appropriately. Take a look at following code to identify the vulnerable code. StringBuilder query = new StringBuilder(); query.append( "select * from user u where u.name in (" + namesString + ")" ); try { Connection connection = getConnection(); PreparedStatement statement = connection.prepareStatement(query.toString()); resultSet = statement.executeQuery(); } Array is Stored Directly Instances of this vulnerability, Array is stored directly, could help the attacker change the objects stored in array outside of program, and the program behave in inconsistent manner as the reference to the array passed to method is held by the caller/invoker. The solution is to make a copy within the object when it gets passed. In this manner, a subsequent modification of the collection won’t affect the array stored within the object. You could read the details on following stackoverflow page. Following code represents the vulnerability: // Note that values is a String array in the code below. // public void setValues(String[] somevalues) { this.values = somevalues; }
September 19, 2014
by Ajitesh Kumar
· 19,577 Views · 1 Like
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AngularJS Coding Best Practices
This article lists some of the best practices that would be useful for developers while they are coding with AngularJS. These are out of my own experiences while working on AngularJS and do not warranty the entire list. I am sure there can be more to this list and thus, request my readers to suggest/comment such that they could be added to the list below. Found some of the following pages which presents a set of good practices you would want to refer. Thanks to the readers for the valuable contribution. AngularJS Style Guide App Structure Best practices Initialization One should try and place the
September 8, 2014
by Ajitesh Kumar
· 74,704 Views · 4 Likes
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Secure REST Services Using Spring Security
Overview : Recently, I was working on a project which uses a REST services layer to communicate with the client application (GWT application). So I have spent a lot of to time to figure out how to secure the REST services with Spring Security. This article describes the solution I found, and I have implemented. I hope that this solution will be helpful to someone and will save a much valuable time. The solution : In a normal web application, whenever a secured resource is accessed Spring Security check the security context for the current user and will decide either to forward him to login page (if the user is not authenticated), or to forward him to the resource not authorised page (if he doesn’t have the required permissions). In our scenario this is different, because we don’t have pages to forward to, we need to adapt and override Spring Security to communicate using HTTP protocols status only, below I liste the things to do to make Spring Security works best : The authentication is going to be managed by the normal form login, the only difference is that the response will be on JSON along with an HTTP status which can either code 200 (if the autentication passed) or code 401 (if the authentication failed) ; Override the AuthenticationFailureHandler to return the code 401 UNAUTHORIZED ; Override the AuthenticationSuccessHandler to return the code 20 OK, the body of the HTTP response contain the JSON data of the current authenticated user ; Override the AuthenticationEntryPoint to always return the code 401 UNAUTHORIZED. This will override the default behavior of Spring Security which is forwarding the user to the login page if he don’t meet the security requirements, because on REST we don’t have any login page ; Override the LogoutSuccessHandler to return the code 20 OK ; Like a normal web application secured by Spring Security, before accessing a protected service, it is mandatory to first authenticate by submitting the password and username to the Login URL. Note: The following solution requires Spring Security in version minimum 3.2. Overriding the AuthenticationEntryPoint : Class extends org.springframework.security.web.AuthenticationEntryPoint, and implements only one method, which sends response error (with 401 status code) in cause of unauthorized attempt. @Component public class HttpAuthenticationEntryPoint implements AuthenticationEntryPoint { @Override public void commence(HttpServletRequest request, HttpServletResponse response, AuthenticationException authException) throws IOException { response.sendError(HttpServletResponse.SC_UNAUTHORIZED, authException.getMessage()); } } Overriding the AuthenticationSuccessHandler : The AuthenticationSuccessHandler is responsible of what to do after a successful authentication, by default it will redirect to an URL, but in our case we want it to send an HTTP response with data. @Component public class AuthSuccessHandler extends SavedRequestAwareAuthenticationSuccessHandler { private static final Logger LOGGER = LoggerFactory.getLogger(AuthSuccessHandler.class); private final ObjectMapper mapper; @Autowired AuthSuccessHandler(MappingJackson2HttpMessageConverter messageConverter) { this.mapper = messageConverter.getObjectMapper(); } @Override public void onAuthenticationSuccess(HttpServletRequest request, HttpServletResponse response, Authentication authentication) throws IOException, ServletException { response.setStatus(HttpServletResponse.SC_OK); NuvolaUserDetails userDetails = (NuvolaUserDetails) authentication.getPrincipal(); User user = userDetails.getUser(); userDetails.setUser(user); LOGGER.info(userDetails.getUsername() + " got is connected "); PrintWriter writer = response.getWriter(); mapper.writeValue(writer, user); writer.flush(); } } Overriding the AuthenticationFailureHandler : The AuthenticationFaillureHandler is responsible of what to after a failed authentication, by default it will redirect to the login page URL, but in our case we just want it to send an HTTP response with the 401 UNAUTHORIZED code. @Component public class AuthFailureHandler extends SimpleUrlAuthenticationFailureHandler { @Override public void onAuthenticationFailure(HttpServletRequest request, HttpServletResponse response, AuthenticationException exception) throws IOException, ServletException { response.setStatus(HttpServletResponse.SC_UNAUTHORIZED); PrintWriter writer = response.getWriter(); writer.write(exception.getMessage()); writer.flush(); } } Overriding the LogoutSuccessHandler : The LogoutSuccessHandler decide what to do if the user logged out successfully, by default it will redirect to the login page URL, because we don’t have that I did override it to return an HTTP response with the 20 OK code. @Component public class HttpLogoutSuccessHandler implements LogoutSuccessHandler { @Override public void onLogoutSuccess(HttpServletRequest request, HttpServletResponse response, Authentication authentication) throws IOException { response.setStatus(HttpServletResponse.SC_OK); response.getWriter().flush(); } } Spring security configuration : This is the final step, to put all what we did together, I prefer using the new way to configure Spring Security which is with Java no XML, but you can easily adapt this configuration to XML. @Configuration @EnableWebSecurity public class WebSecurityConfig extends WebSecurityConfigurerAdapter { private static final String LOGIN_PATH = ApiPaths.ROOT + ApiPaths.User.ROOT + ApiPaths.User.LOGIN; @Autowired private NuvolaUserDetailsService userDetailsService; @Autowired private HttpAuthenticationEntryPoint authenticationEntryPoint; @Autowired private AuthSuccessHandler authSuccessHandler; @Autowired private AuthFailureHandler authFailureHandler; @Autowired private HttpLogoutSuccessHandler logoutSuccessHandler; @Bean @Override public AuthenticationManager authenticationManagerBean() throws Exception { return super.authenticationManagerBean(); } @Bean @Override public UserDetailsService userDetailsServiceBean() throws Exception { return super.userDetailsServiceBean(); } @Bean public AuthenticationProvider authenticationProvider() { DaoAuthenticationProvider authenticationProvider = new DaoAuthenticationProvider(); authenticationProvider.setUserDetailsService(userDetailsService); authenticationProvider.setPasswordEncoder(new ShaPasswordEncoder()); return authenticationProvider; } @Override protected void configure(AuthenticationManagerBuilder auth) throws Exception { auth.authenticationProvider(authenticationProvider()); } @Override protected AuthenticationManager authenticationManager() throws Exception { return super.authenticationManager(); } @Override protected void configure(HttpSecurity http) throws Exception { http.csrf().disable() .authenticationProvider(authenticationProvider()) .exceptionHandling() .authenticationEntryPoint(authenticationEntryPoint) .and() .formLogin() .permitAll() .loginProcessingUrl(LOGIN_PATH) .usernameParameter(USERNAME) .passwordParameter(PASSWORD) .successHandler(authSuccessHandler) .failureHandler(authFailureHandler) .and() .logout() .permitAll() .logoutRequestMatcher(new AntPathRequestMatcher(LOGIN_PATH, "DELETE")) .logoutSuccessHandler(logoutSuccessHandler) .and() .sessionManagement() .maximumSessions(1); http.authorizeRequests().anyRequest().authenticated(); } } This was a sneak peak at the overall configuration, I attached in this article a Github repository containing a sample project https://github.com/imrabti/gwtp-spring-security. I hope this will help some of you developers struggling to figure out a solution, please feel free to ask any questions, or post any enhancements that can make this solution better.
September 5, 2014
by Mrabti Idriss
· 108,015 Views · 8 Likes
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Spring Security Run-As example using annotations and namespace configuration
Spring Security offers an authentication replacement feature, often referred to as Run-As, that can replace the current user's authentication (and thus permissions) during a single secured object invocation. Using this feature makes sense when a backend system invoked during request processing requires different privileges than the current application. For example, an application might want to expose a financial transaction log to the currently logged in user, but the backend system that provides it only permits this action to the members of a special "auditor" role. The application can not simply assign this role to the user as that would potentially permit them to execute other restricted actions. Instead, the user can be given this right exclusively for viewing their transaction log. Only two classes are used to implement this feature. Instances of RunAsManager are tasked with producing the actual replacement authentication tokens. A sensible default implementation is already provided by Spring Security. As with other types of authentication, it is also necessary to register an instance of an appropriate AuthenticationProvider. Tokens produced by runAsManager are signed with the provided key (my_run_as_key in the example above) and are later checked against the same key by runAsAuthenticationProvider, in order to mitigate the risk of fake tokens being provided. These keys can have any value, but need to be the same in both objects. Otherwise, runAsAuthenticationProvider will reject the produced tokens as invalid. If an instance is registered, RunAsManager will be invoked by AbstractSecurityInterceptor for every intercepted object invocation for which the user has already been given access. If RunAsManager returns a token, this token will be used be used instead of the original one for the duration of the invocation, thus granting the user different privileges. There are two key points here. In order for the authentication replacement feature to do anything, the call has to actually be secured (and thus intercepted), and the user has to already have been granted access. To register a RunAsManager instance with the method security interceptor, something similar to the following is needed: Now, all methods secured by the @Secured annotation will be able to trigger RunAsManager. One important point here is that global-method-security will only work in the Spring context in which it is defined. In Spring MVC applications, there usually are two Spring contexts: the parent context, attached to ContextLoaderListener, and the child context, attached toDispatcherServlet. To secure Controller methods in this way, global-method-security must be added to DispatcherServlet's context. To secure methods in beans not in this context, global-method-security should also be added to ContextLoaderListener's context. Otherwise, security annotations will be ignored. The default implementation of RunAsManager (RunAsManagerImpl) will inspect the secured object's configuration and if it finds any attributes prefixed with RUN_AS_, it will create a token identical to the original, with the addition of one new GrantedAuthorty per RUN_AS_ attribute found. The new GrantedAuthority will be a role (prefixed by ROLE_ by default) named like the found attribute without the RUN_AS_ prefix. So, if a user with a role ROLE_REGISTERED_USER invokes a method annotated with @Secured({"ROLE_REGISTERED_USER","RUN_AS_AUDITOR"}), e.g. @Controller public class TransactionLogController { @Secured({"ROLE_REGISTERED_USER","RUN_AS_AUDITOR"}) //Authorities needed for method access and authorities added by RunAsManager prefixed with RUN_AS_ @RequestMapping(value = "/transactions", method = RequestMethod.GET) //Spring MVC configuration. Not related to security @ResponseBody //Spring MVC configuration. Not related to security public List getTransactionLog(...) { ... //Invoke something in the backend requiring ROLE_AUDITOR { ... //User does not have ROLE_AUDITOR here } the resulting token created by RunAsManagerImpl with be granted ROLE_REGISTERED_USER and ROLE_AUDITOR. Thus, the user will also be allowed actions, normally reserved for ROLE_AUDITOR members, during the current invocation, permitting them, in this case, to access the transaction log.To enable runAsAuthenticationProvider, register it as usual: ... other authentication-providers used by the application ... This is all that is necessary to have the default implementation activated. Still, this setting will not work for methods secured by @PreAuthorize and @PostAuthorize annotations as their configuration attributes are differently evaluated (they are SpEL expressions and not a simple list or required authorities like with @Secured) and will not be recognized by RunAsManagerImpl. For this scenario to work, a custom RunAsManager implementation is required, as, at least at the time of writing, no applicable implementation is provided by Spring. A custom RunAsManager implementation for use with @PreAuthorize/@PostAuthorize A convenient implementation relying on a custom annotation is provided below: public class AnnotationDrivenRunAsManager extends RunAsManagerImpl { @Override public Authentication buildRunAs(Authentication authentication, Object object, Collection attributes) { if(!(object instanceof ReflectiveMethodInvocation) || ((ReflectiveMethodInvocation)object).getMethod().getAnnotation(RunAsRole.class) == null) { return super.buildRunAs(authentication, object, attributes); } String roleName = ((ReflectiveMethodInvocation)object).getMethod().getAnnotation(RunAsRole.class).value(); if (roleName == null || roleName.isEmpty()) { return null; } GrantedAuthority runAsAuthority = new SimpleGrantedAuthority(roleName); List newAuthorities = new ArrayList(); // Add existing authorities newAuthorities.addAll(authentication.getAuthorities()); // Add the new run-as authority newAuthorities.add(runAsAuthority); return new RunAsUserToken(getKey(), authentication.getPrincipal(), authentication.getCredentials(), newAuthorities, authentication.getClass()); } } This implementation will look for a custom @RunAsRole annotation on a protected method (e.g. @RunAsRole("ROLE_AUDITOR")) and, if found, will add the given authority (ROLE_AUDITOR in this case) to the list of granted authorities. RunAsRole itself is just a simple custom annotation: @Retention(RetentionPolicy.RUNTIME) @Target(ElementType.METHOD) public @interface RunAsRole { String value(); } This new implementation would be instantiated in the same way as before: And registered in a similar fashion: The expression-handler is always required for pre-post-annotations to work. It is a part of the standard Spring Security configuration, and not related to the topic described here. Both pre-post-annotations and secured-annotations can be enabled at the same time, but should never be used in the same class. The protected controller method from above could now look like this: @Controller public class TransactionLogController { @PreAuthorize("hasRole('ROLE_REGISTERED_USER')") //Authority needed to access the method @RunAsRole("ROLE_AUDITOR") //Authority added by RunAsManager @RequestMapping(value = "/transactions", method = RequestMethod.GET) //Spring MVC configuration. Not related to security @ResponseBody //Spring MVC configuration. Not related to security public List getTransactionLog(...) { ... //Invoke something in the backend requiring ROLE_AUDITOR { ... //User does not have ROLE_AUDITOR here }
July 7, 2014
by Bojan Tomić
· 23,185 Views · 1 Like
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Spring Security Misconfiguration
I recently saw Mike Wienser’s SpringOne2GX talk about Application Security Pitfalls. It is very informative and worth watching if you are using Spring’s stack on servlet container. It reminded me one serious Spring Security Misconfiguration I was facing once. Going to explain it on Spring’s Guide Project called Securing a Web Application. This project uses Spring Boot, Spring Integration and Spring MVC. Project uses these views: @Configuration public class MvcConfig extends WebMvcConfigurerAdapter { @Override public void addViewControllers(ViewControllerRegistry registry) { registry.addViewController("/home").setViewName("home"); registry.addViewController("/").setViewName("home"); registry.addViewController("/hello").setViewName("hello"); registry.addViewController("/login").setViewName("login"); } } Where “/home”, “/” and “/login” URLs should be publicly accessible and “/hello” should be accessible only to authenticated user. Here is original Spring Security configuration from Guide: @Configuration @EnableWebMvcSecurity public class WebSecurityConfig extends WebSecurityConfigurerAdapter { @Override protected void configure(HttpSecurity http) throws Exception { http .authorizeRequests() .antMatchers("/", "/home").permitAll() .anyRequest().authenticated(); http .formLogin() .loginPage("/login") .permitAll() .and() .logout() .permitAll(); } @Override protected void configure(AuthenticationManagerBuilder auth) throws Exception { auth .inMemoryAuthentication() .withUser("user").password("password").roles("USER"); } } Nice and explanatory as all Spring’s Guides are. First “configure” method registers “/” and “home” as public and specifies that everything else should be authenticated. It also registers login URL. Second “configure” method specifies authentication method for role “USER”. Of course you don’t want to use it like this in production :). Now I am going to slightly amend this code. @Override protected void configure(HttpSecurity http) throws Exception { //!!! Don't use this example !!! http .authorizeRequests() .antMatchers("/hello").hasRole("USER"); //... same as above ... } Everything is public and private endpoints have to be listed. You can see that my amended code have the same behavior as original. In fact it saved one line of code. But there is serious problem with this. What if my I need to introduce new private endpoint? Let’s say I am not aware of the fact that it needs to be registered in Spring Security configuration. My new endpoint would be public. Such misconfiguration is really hard to catch and can lead to unwanted exposure of URLs. So conclusion is: Always authenticate all endpoints by default.
June 17, 2014
by Lubos Krnac
· 12,173 Views · 1 Like
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Cisco AnyConnect and Hyper-V - Connect to a VPN from Inside a VM Session
Clients and VMs and VPNs, Oh My! As regular readers of this blog may be aware, I recently hung up my technical evangelist hat, and made the jump back into full-time consulting. Consistent with best practices, I decided that when working with a new client, the best course of action would be to set up a new virtual machine to keep all of the development environment, tools, and files isolated from anything on my host machine, which helps minimize the risk that installing the latest bleeding-edge tools (which are good to have to stay ahead of the learning curve) don't endanger the work I'm doing for the client. With my current client, I need to be able to access files, servers, and tools on their remote network, which they enable via the Cisco AnyConnect VPN client software. So far, so good. I had no trouble at all installing and connecting with this software from my laptop over my FiOS connection. Just like being at the office. The Tricky Part Unfortunately, the VPN connection does not pass through to the virtual machine I set up, using client Hyper-V on Windows 8.1 (update 1). Which is interesting, because while I was onsite recently, when I connected to the LAN directly via cable, that connection would pass through to the VM. But since I'm not a networking geek, I'll leave that to others to explain. So, the next step was to try installing the VPN client software in the VM itself. But it was not to be. The client software installs fine, but I found that when I tried to connect, I'd get the following error message: OK, so now what? Well, truth be told, since I didn't have time to troubleshoot this immediately, I set the problem aside for a while, which can be a good way to let your brain work on the problem while you're doing other things. Or sometimes, you get lucky...this was one of those times. Basic or Enhanced? By good fortune, this morning, I ran across a brief blog post by Osama Mourad (No, not the same person who runs one of the CMAP Special Interest Groups), which suggested that connecting the VPN was possible "if connected to the VM using Hyper-V Manager." A bit cryptic, but it gave me hope that it was at least possible. Here's where luck comes in. I was trying to see if there was a different way to connect to the VM from Hyper-V Manager, when I noticed that if I did not have the VM session window full-screen, there is an icon at the end of the toolbar that looks like this: That button switches the VM session from Enhanced Session Mode (the default in newer versions of Hyper-V), which uses a Remote Desktop Connection to interact with the VM, to Basic Session Mode, which provides simple screen, keyboard, and mouse redirection. And beautifully, it turns out that in Basic Session Mode, connecting the VPN works just fine. And once connected, you can switch back to Enhanced Session Mode, and the VPN will remain connected. Conclusion Using a virtual machine is a good practice for keeping your client environment isolated from your day-to-day experiments or bleeding edge tools, etc. And it also has the advantage of making the environment portable. You can store the VM files on a portable drive, or copy them from one machine to another if you need to migrate systems. But along with the convenience comes the occasional head-scratcher or stumbling block. I hope that this post will help anyone else who runs into this particular issue resolve their problem. You can learn more about Enhanced Session Mode from this TechNet article. My thanks to Osama for the clue that helped me track down the solution.
May 26, 2014
by G. Andrew Duthie
· 17,939 Views
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Java EE: The Basics
wanted to go through some of the basic tenets, the technical terminology related to java ee. for many people, java ee/j2ee still mean servlets, jsps or maybe struts at best. no offence or pun intended! this is not a java ee 'bible' by any means. i am not capable enough of writing such a thing! so let us line up the 'keywords' related to java ee and then look at them one by one java ee java ee apis (specifications) containers services multitiered applications components let's try to elaborate on the above mentioned points. ok. so what is java ee? 'ee' stands for enterprise edition. that essentially makes java ee - java enterprise edition. if i had to summarize java ee in a couple of sentences, it would go something like this "java ee is a platform which defines 'standard specifications/apis' which are then implemented by vendors and used for development of enterprise (distributed, 'multi-tired', robust) 'applications'. these applications are composed of modules or 'components' which use java ee 'containers' as their run-time infrastructure." what is this 'standardized platform' based upon? what does it constitute? the platform revolves around 'standard' specifications or apis . think of these as contracts defined by a standard body e.g. enterprise java beans (ejb), java persistence api (jpa), java message service (jms) etc. these contracts/specifications/apis are implemented by different vendors e.g. glassfish, oracle weblogic, apache tomee etc alright. what about containers? containers can be visualized as 'virtual/logical partitions' . each container supports a subset of the apis/specifications defined by the java ee platform they provide run-time 'services' to the 'applications' which they host the java ee specification lists 4 types of containers ejb container web container application client container applet container java ee containers i am not going to dwell into details of these containers in this post. services?? well, 'services' are nothing but a result of the vendor implementations of the standard 'specifications' (mentioned above). examples of specifications are - jersey for jax-rs (restful services), tyrus (web sockets), eclipselink (jpa), weld (cdi) etc. the 'container' is the interface between the deployed application ('service' consumer) and the application server. here is a list of 'services' which are rendered by the 'container' to the underlying 'components' (this is not an exhaustive list) persistence - offered by the java persistence api (jpa) which drives object relational mapping (orm) and an abstraction for the database operations. messaging - the java message service (jms) provides asynchronous messaging between disparate parts of your applications. contexts & dependency injection - cdi provides loosely coupled and type safe injection of resources. web services - jaxrs and jaxws provide support for rest and soap style services respectively transaction - provided by the java transaction api (jta) implementation what is a typical java ee 'application'? what does it comprise of? applications are composed of different ' components ' which in turn are supported by their corresponding ' container ' supported 'component' types are: enterprise applications - make use of the specifications like ejb, jms, jpa etc and are executed within an ejb container web applications - they leverage the servlet api, jsp, jsf etc and are supported by a web container application client - executed in client side. they need an application client container which has a set of supported libraries and executes in a java se environment. applets - these are gui applications which execute in a web browser. how are java ee applications structured? as far as java ee 'application' architecture is concerned, they generally tend follow the n-tier model consisting of client tier, server tier and of course the database (back end) tier client tier - consists of web browsers or gui (swing, java fx) based clients. web browsers tend to talk to the 'web components' on the server tier while the gui clients interact directly with the 'business' layer within the server tier server tier - this tier comprises of the dynamic web components (jsp, jsf, servlets) and the business layer driven by ejbs, jms, jpa, jta specifications. database tier - contains 'enterprise information systems' backed by databases or even legacy data repositories. generic 3-tier java ee application architecture java ee - bare bones, basics.... as quickly and briefly as i possibly could. that's all for now! :-) stay tuned for more java ee content, specifically around the latest and greatest version of the java ee platform --> java ee 7 happy reading!
April 29, 2014
by Abhishek Gupta DZone Core CORE
· 40,813 Views · 3 Likes
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jdeps: JDK 8 Command-line Static Dependency Checker
Here's a great JDK 8 command-line static dependency checker.
March 27, 2014
by Dustin Marx
· 24,223 Views · 2 Likes
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How HTML5 Apps Can be More Secure than Native Mobile Apps
As businesses accelerate their move toward making B2E applications available to employees on mobile devices, the subject of mobile application security is getting more attention. Mobile Device Management (MDM) solutions are being deployed in the largest enterprises - but there are still application-level security issues that are important to consider. Furthermore, medium size businesses are moving to mobilize their applications prior to having a formalized MDM solution or policy in place. A key element of a mobile app strategy is whether to go Native, Hybrid, or pure HTML5. As an early proponent of HTML5 platforms, Gizmox has been thinking about the security angle of HTML5 applications for a long time. In a recent webinar, we discussed 4 ways that HTML5 - done right - can be more secure than native apps. 1. Applications should leverage HTML5's basic security model HTML5 represents a revolutionary step for HTML-based browsers as the first truly cross-platform technology for rich, interactive applications. It has earned endorsements by all the major IT vendors (e.g. Google, Microsoft, IBM, Oracle, etc...). Security of applications and websites has been a consideration from the start of HTML5 development. The first element of the security model is that HTML5 applications live within the secure shell of the browser sandbox. Application code is to a large degree insulated from the device. The browser's interaction with the device and any other application on the device is highly limited. This makes it difficult for HTML5 application code to influence other applications/data on the device or for other applications to interact with the application running on the browser. The second element is that, built correctly, HTML5 thin clients are "secure by design." Application logic running on the server insultates sensitive intellectual property from the client. Proper design strategies would include minimal or no data caching; keeping tokens, passwords, credentials, and security profiles on the server; minimizing logic on the client - focusing on pure UI interaction with the server. Finally, HTML5 apps should be architected to ensure that no data is left behind in cache. 2. HTML5 apps can be containerized within secure browsers Secure browsers are just one element of MDM that can be deployed on their own to enhance application security. HTML5 application security can be extended with the use of secure browsers that restrict access to enterprise-approved URLs, prevent cross-site scripting, and integrate with company VPNs. Furthermore, secure browsers further harden the interaction between HTML5 applications and the device, the device OS and other applciations on the device. 3. Integration with Mobile Device Management MDM solutions play a variety of security roles including application inventory management (i.e. who gets access to what on which device), application distribution (i.e. through enterprise app store), implementation of security standards (e.g. passwords, encryption, VPN, authentication, etc...), and implemetation of enterprise access control policies. While MDM was in part conceived to enable secure distribution and control of native applications, HTML5 apps can be managed and further secured as well. While full MDM solutions are not required for HTML5 security, HTML5 apps can be integrated into a broader mobile security strategy that incorporates MDM. 4. HTML5 was conceived for the BYOD world The complexity of managing security for native apps gets multiplied as application variants are created for different mobile device form factors and operating systems. With cross-platform HTML5 applications that run on any desktop, tablet, or smartphone, security strategy is implemented and controlled centrally. Updates and security fixes are implemented on the server and there are no concerns with users not applying updates to the apps on their devices. There are many reasons to evaluate HTML5 as the platform for mobile business applications. Security of HTML5 apps (built with good practices and leveraging a full platform like Visual WebGui) is a particularly compelling reason to consider. Check out this slide share from recent webinar on HTML5 security strategies. Security strategies for html5 enterprise mobile apps from Gizmox
March 15, 2014
by Moran Shayovitch
· 5,153 Views
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The Risks Of Big-Bang Deployments And Techniques For Step-wise Deployment
If you ever need to persuade management why it might be better to deploy a larger change in multiple stages and push it to customers gradually, read on. A deployment of many changes is risky. We want therefore to deploy them in a way which minimizes the risk of harm to our customers and our companies. The deployment can be done either in an all-at-once (also known as big-bang) way or a gradual way. We will argue here for the more gradual (“stepwise”) approach. Big-bang or stepwise deployment? A big-bang deployment seems to be the natural thing to do: the full solution is developed and tested and then replaces the current system at once. However, it has two crucial flaws. First, it assumes that most defects can be discovered by testing. However, due to differences in test/prod environments, unknown dependencies, and the sheer scale of a typical larger system there always will be problems that are not discovered until production deployment or even until the application runs for a while in production (whichapplies even to airplanes). The more parts have been changed, the more of these production defects will happen at the same time. A gradual deployment makes it possible to discover and handle them one by one. Second, the more complex the deployment, the higher chance of human error(s), i.e. the deployment itself is a likely source of serious defects. Some of the drawbacks of a big-bang deployment in more detail: Complexity: A big-bang deployment requires coordination of many people and “moving parts” that depend on each other, providing a huge opportunity for human mistake (i.e. there will be mistakes). Lot of time: Such a deployment requires lot of time (typically also more than planed/expected) and thus lot of downtime when users cannot use the system. Hard troubleshooting: With a network of inter-dependent parts that changed all at the same time, while perhaps also changing the infrastructure (i.e. connections between them), it is extremely hard to pinpoint the source of defects, thus considerably increasing the time to detect and correct defects while also increasing the risk of people stepping on the toes of each other and “panic fixes” that either cause more problems than they remove or are not good enough (as the rollback that sped upKnight’s downfall). Rollback is likely either impossible or equally time-consuming and risky as the deployment itself, thus increasing the impact of defects and inviting even more human errors. Impact: Deploying everything to all users at the same time means that everybody will be impacted by a potential defect/error/mistake. Long freeze: All needs to be tested together after all development is finished, which requires a lot of time while the code is frozen and no more fixes and changes can get into production for weeks. Risk mitigation The goal of a good deployment plan is to mitigate the risk of the deployment and get it to an acceptable level. There are two aspects to risk: the probability of a defect and the impact of the defect. The following table shows how the possible measures affect them: Defect probability reduction Defect impact reduction testing stepwise deployment gradual migration of users to the new version (f.ex. 1 in 1000 or particular subsets) rollback mechanism => these also lead to much lower time to detect and fix defects Practices for stepwise deployment Enable stepwise deployment: Use parallel change and other Continuous Delivery techniques to make it possible to deploy updated components independently from each other and to switch on/off new features and to switch what versions of the components they depend on are currently used. (Parallel change – keeping the old and new code and being able to use one or the other – is crucial here. Also notice that parallel change applies also to data – you will need to evolve your data schema gradually and keep both old and new one at the same time in a period of time.) Enable rollback. The previous measure – stepwise deployment – makes it also easy(ier) to roll-back the changes by switching to a previous version of a dependency or by switching back to the old code. Migrate users gradually to the new version, i.e. expose the new version only to a small subset of the users initially and increase that subset until everybody uses it. This can be done f.ex. by deploying to only a subset of servers and sending a random/particular subset of users to the new servers but there are also ways if you have only a single machine. (See f.ex. my post Webapp Blue-Green Deployment Without Breaking Sessions/With Fallback With HAProxy.) Monitoring – make sure you are able to monitor flow of users through the system and detect any anomalies and errors early, long before angry calls from the business. Tools such as Logstash, Google Analytics (with custom events from JavaScript), client-side error logging via one of existing services or a custom solution are invaluable. About these ads
February 20, 2014
by Jakub Holý
· 22,328 Views
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Blast from the Past - 'The XML Diff and Patch GUI Tool'
I needed to diff some OPML files today and came across this project. Even through it's 10 years old, it still mostly worked and the best part is it's a source distrib... :) The XML Diff and Patch GUI Tool Amol Kher Microsoft Corporation July 2004 Applies to: the XML Diff and Patch GUI tool Summary: This article shows how to use the XmlDiff class to compare two XML files and show these differences as an HTML document in a .NET Framework 1.1 application. The article also shows how to build a WinForms application for comparing XML files. Contents Introduction An Overview of the XML Diff and Patch API XML Diff and Patch Meets Winforms Working with XML DiffGrams Other Features of the XML Diff and Patch Tool Introduction There is no good command line tool that can be used to compare two XML files and view the differences. There is an online tool called XML Diff and Patch that's available on the GotDotNet website under the XML Tools section. For those who have not, you can find it at Microsoft XML Diff and Patch 1.0 [GD: yes, this link is busted... you can download it below]. It is a very convenient tool for those who want to compare the difference between two XML files. Comparing XML files is different from comparing regular text files because one wants to compare logical differences in the XML nodes not just differences in text. For example one may want to compare XML documents and ignore white space between elements, comments or processing instructions. The XML Diff and Patch tool allows one to perform such comparisons but it is primarily available as an online web application. We cannot take this tool and use it from command line. This article focuses on developing a command-line tool by reusing code from the XML Diff and Patch installation and samples. The tool works very similar to the WinDiff utility; it presents the differences in a separate window and highlights them. The XML Diff and Patch tool contains a library that contains an XmlDiff class, which can be used to compare two XML documents. The Compare method on this class takes two files and either returns true, if the files are equal, or generates an output file called an XML diffgram containing a list of differences between the files. The XmlDiff class can be supplied an options class XmlDiffOptions that can be used to set the various options for comparing files. ... Microsoft Downloads - XML Diff & Patch GUI Tool Winforms application that can be used to compare 2 XML files. Version: 1.0 Date Published: 7/14/2004 xmldiffgui.msi, 278 KB This code sample shows how to build a Windows forms application that utilizes the XML Diff & Patch library to show the difference between 2 XML files. There's a bug somewhere in it in that it was giving me an error when trying to load the HTML into an IE window, but that's likely a path thing. In the end, it executed and diff'd the two XML files. And since we do have the source... :) Another blast from the past is that this was available on the old GotDotNet site. I miss that site... :(
February 7, 2014
by Greg Duncan
· 13,078 Views
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AES-256 Encryption with Java and JCEKS
Security has become a great topic of discussion in the last few years due to the recent releasing of documents from Edward Snowden and the explosion of hacking against online commerce stores like JC Penny, Sony andTarget. While this post will not give you all of the tools to help prevent the use of illegally sourced data, this post will provide a starting point for building a set of tools and tactics that will help prevent the use of data by other parties. This post will show how to adopt AES encryption for strings in a Java environment. It will talk about creating AES keys and storing AES keys in a JCEKS keystore format. A working example of the code in this blog is located athttps://github.com/mike-ensor/aes-256-encryption-utility It is recommended to read each section in order because each section builds off of the previous section, however, this you might want to just jump quickly jump to a particular section. Setup - Setup and create keys with keytool Encrypt - Encrypt messages using byte[] keys Decrypt - Decrypt messages using same IV and key from encryption Obtain Keys from Keystore - Obtain keys from keystore via an alias What is JCEKS? JCEKS stands for Java Cryptography Extension KeyStore and it is an alternative keystore format for the Java platform. Storing keys in a KeyStore can be a measure to prevent your encryption keys from being exposed. Java KeyStores securely contain individual certificates and keys that can be referenced by an alias for use in a Java program. Java KeyStores are often created using the "keytool" provided with the Java JDK. NOTE: It is strongly recommended to create a complex passcode for KeyStores to keep the contents secure. The KeyStore is a file that is considered to be public, but it is advisable to not give easy access to the file. Setup All encryption is governed by laws of each country and often have restrictions on the strength of the encryption. One example is that in the United States, all encryption over 128-bit is restricted if the data is traveling outside of the boarder. By default, the Java JCE implements a strength policy to comply with these rules. If a stronger encryption is preferred, and adheres to the laws of the country, then the JCE needs to have access to the stronger encryption policy. Very plainly put, if you are planning on using AES 256-bit encryption, you must install theUnlimited Strength Jurisdiction Policy Files. Without the policies in place, 256-bit encryption is not possible. Installation of JCE Unlimited Strength Policy This post is focusing on the keys rather than the installation and setup of the JCE. The installation is rather simple with explicit instructions found here (NOTE: this is for JDK7, if using a different JDK, search for the appropriate JCE policy files). Keystore Setup When using the KeyTool manipulating a keystore is simple. Keystores must be created with a link to a new key or during an import of an existing keystore. In order to create a new key and keystore simply type: keytool -genseckey -keystore aes-keystore.jck -storetype jceks -storepass mystorepass -keyalg AES -keysize 256 -alias jceksaes -keypass mykeypass Important Flags In the example above here are the explanations for the keytool's parameters: Keystore Parameters genseckey Generate SecretKey. This is the flag indicating the creation of a synchronous key which will become our AES key keystore Location of the keystore. If the keystore does not exist, the tool will create a new store. Paths can be relative or absolute but must be local storetype this is the type of store (JCE, PK12, JCEKS, etc). JCEKS is used to store symmetric keys (AES) not contained within a certificate. storepass password related to the keystore. Highly recommended to create a strong passphrase for the keystore Key Parameters keyalg algorithm used to create the key (AES/DES/etc) keysize size of the key (128, 192, 256, etc) alias alias given to the newly created key in which to reference when using the key keypass password protecting the use of the key Encrypt As it pertains to data in Java and at the most basic level, encryption is an algorithmic process used to programmatically obfuscate data through a reversible process where both parties have information pertaining to the data and how the algorithm is used. In Java encryption, this involves the use of a Cipher. A Cipher object in the JCE is a generic entry point into the encryption provider typically selected by the algorithm. This example uses the default Java provider but would also work with Bouncy Castle. Generating a Cipher object Obtaining an instance of Cipher is rather easy and the same process is required for both encryption and decryption. (NOTE: Encryption and Decryption require the same algorithm but do not require the same object instance) Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding"); Once we have an instance of the Cipher, we can encrypt and decrypt data according to the algorithm. Often the algorithm will require additional pieces of information in order to encrypt/decrypt data. In this example, we will need to pass the algorithm the bytes containing the key and an initial vector (explained below). Initialization In order to use the Cipher, we must first initialize the cipher. This step is necessary so we can provide additional information to the algorithm like the AES key and the Initial Vector (aka IV). cipher.init(Cipher.ENCRYPT_MODE, secretKeySpecification, initialVector); Parameters The SecretKeySpecification is an object containing a reference to the bytes forming the AES key. The AES key is nothing more than a specific sized byte array (256-bit for AES 256 or 32 bytes) that is generated by the keytool(see above). Alternative Parameteters There are multiple methods to create keys such as a hash including a salt, username and password (or similar). This method would utilize a SHA1 hash of the concatenated strings, convert to bytes and then truncate result to the desired size. This post will not show the generation of a key using this method or the use of a PBE key method using a password and salt. The password and/or salt usage for the keys is handled by the keytool using the inputs during the creation of new keys. Initialization Vector The AES algorithm also requires a second parameter called the Initialiation Vector. The IV is used in the process to randomize the encrypted message and prevent the key from easy guessing. The IV is considered a publicly shared piece of information, but again, it is not recommended to openly share the information (for example, it wouldn't be wise to post it on your company's website). When encrypting a message, it is not uncommon to prepend the message with the IV since the IV will be a set/known size based on the algorithm. NOTE: the AES algorithm will output the same result if using the same IV, key and message. It is recommended that the IV be randomly created each time an encryption takes place. With the newly initialized Cipher, encrypting a message is simple. Simply call: byte[] encryptedMessageInBytes = Cipher.doFinal((message.getBytes("UTF-8")); String base64EncodedEncryptedMsg = BaseEncoding.base64().encode(encryptedMessageInBytes); String base32EncodedEncryptedMsg = BaseEncoding.base32().encode(encryptedMessageInBytes); Encoding Results Byte arrays are difficult to visualize since they often do not form characters in any charset. The best recommendation to solve this is to represent the bytes in HEX (base-16), Double HEX (base-32) or Base64 format. If the message will be passed via a URL or POST parameter, be sure to use a web-safe Base64 encoding. Google Guava library provides a excellent BaseEncoding utility. NOTE: Remember to decode the encoded message before decrypting. Decrypt Decrypting a message is almost a reverse of the encryption process with a few exceptions. Decryption requires a known initialization vector as a parameter unlike the encryption process generating a random IV. Decryption When decrypting, obtain a cipher object with the same process as the encryption method. The Cipher object will need to utilize the exact same algorithm including the method and padding selections. Once the code has obtained a reference to a Cipher object, the next step is to initialize the cipher for decryption and pass in a reference to a key and the initialization vector. // key is the same byte[] key used in encryption SecretKeySpec secretKeySpecification = new SecretKeySpec(key, "AES"); cipher.init(Cipher.DECRYPT_MODE, secretKeySpecification, initialVector); NOTE: The key is stored in the keystore and obtained by the use of an alias. See below for details on obtaining keys from a keystore Once the cipher has been provided the key, IV and initialized for decryption, the cipher is ready to perform the decryption. byte[] encryptedTextBytes = BaseEncoding.base64().decode(message); byte[] decryptedTextBytes = cipher.doFinal(encryptedTextBytes); String origMessage = new String(decryptedTextBytes); Strategies to keep IV The IV used to encrypt the message is important to decrypting the message therefore the question is raised, how do they stay together. One solution is to Base Encode (see above) the IV and prepend it to the encrypted and encoded message: Base64UrlSafe(myIv) + delimiter + Base64UrlSafe(encryptedMessage). Other possible solutions might be contextual such as including an attribute in an XML file with the IV and one for the alias to the key used. Obtain Key from Keystore The beginning of this post has shown how easy it is to create new AES-256 keys that reference an alias inside of a keystore database. The post then continues on how to encrypt and decrypt a message given a key, but has yet shown how to obtain a reference to the key in a keystore. Solution // for clarity, ignoring exceptions and failures InputStream keystoreStream = new FileInputStream(keystoreLocation); KeyStore keystore = KeyStore.getInstance("JCEKS"); keystore.load(keystoreStream, keystorePass.toCharArray()); if (!keystore.containsAlias(alias)) { thrownew RuntimeException("Alias for key not found"); } Key key = keystore.getKey(alias, keyPass.toCharArray()); Parameters keystoreLocation String - Location to local keystore file location keypass String - Password used when creating or modifying the keystore file with keytool (see above) alias String - Alias used when creating new key with keytool (see above) Conclusion This post has shown how to encrypt and decrypt string based messages using the AES-256 encryption algorithm. The keys to encrypt and decrypt these messages are held inside of a JCEKS formatted KeyStore database created using the JDK provided "keytool" utility. The examples in this post should be considered a solid start to encrypting/decrypting symmetric keys such as AES. This should not be considered the only line of defense when encrypting messages, for example key rotation. Key rotation is a method to mitigate risks in the event of a data breach. If an intruder obtains data and manages to hack a single key, the data contained in multiple files should have used several keys to encrypt the data thus bringing down risk of a total exposure loss. All of the examples in this blog post have been condensed into a simple tool allowing for the viewing of keys inside of a keystore, an operation that is not supported out of the box by the JDK keytool. Each aspect of the steps and topics outlined in this post are available at: https://github.com/mike-ensor/aes-256-encryption-utility. NOTE: The examples, sample code and any reference is to be used at the sole implementers risk and there is no implied warranty or liability, you assume all risks.
February 4, 2014
by Mike Ensor
· 102,516 Views · 2 Likes
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