To build a secure app, you can’t wait to the end and hope to “test security in”. For teams who follow Agile methods like Scrum, this means you have to find a way to add security into Sprints. Here’s how to do it:

Sprint Zero

A few basic security steps need to be included upfront in Sprint Zero:

1. Platform selection – when you are choosing your language and application framework, take some time to understand the security functions they provide. Then look around for security libraries like Apache Shiro (a framework for authentication, session management and access control), Google KeyCzar (crypto), and the OWASP Java Encoder (XSS protection) to fill in any blanks.
2. Data privacy and compliance requirements – make sure that you understand data needs to be protected and audited for compliance purposes (including PII), and what you will need to prove to compliance auditors.
3. Secure development training – check the skill level of the team, fill in as needed with training on secure coding. If you can’t afford training, buy a couple of copies of Iron-Clad Java, and check out SAFECode’s free seminars on secure coding.
4. Coding guidelines and code review guidelines – consider where security fits in. Take a look at CERT’s Secure Java Coding Guidelines.
5. Testing approach – plan for security unit testing in your Continuous Integration pipeline. And choose a static analysis tool and wire it into Continuous Integration too. Plan for pen testing or other security stage gates/reviews later in development.
6. Assigning a security lead - someone on the team who has experience and training in secure development (or who will get extra training in secure development) or someone from infosec, who will act as the point person on risk assessments, lead threat modeling sessions, coordinate pen testing and scanning and triage the vulnerabilities found, bring new developers up to speed.
7. Incident Response - think about how the team will help ops respond to outages and to security incidents.

Early Sprints

The first few Sprints, where you start to work out the design and build out the platform and the first-ofs for key interfaces and integration points, is when the application’s attack surface expands quickly.

You need to do threat modeling to understand security risks and make sure that you are handling them properly.

Start with Adam Shostack’s 4 basic threat modeling questions:

1. What are you building?
2. What can go wrong?
3. What are you going to do about it?
4. Did you do an acceptable job at 1-3?

Delivering Features (Securely)

A lot of development work is business as usual, delivering features that are a lot like the other features that you’ve already done: another screen, another API call, another report or another table. There are a few basic security concerns that you need to keep in mind when you are doing this work. Make sure that problems caught by your static analysis tool or security tests are reviewed and fixed. Watch out in code reviews for proper use of frameworks and libraries, and for error and exception handling and defensive coding.

Take some extra time when a security story comes up (a new security feature or a change to security or privacy requirements), and think about abuser stories whenever you are working on a feature that deals with something important like money, or confidential data, or secrets, or command-and-control functions.

Heavy Lifting

You need to think about security any time you are doing heavy lifting: large-scale refactoring, upgrading framework code or security plumbing or the run-time platform, introducing a new API or integrating with a new system. Just like when you are first building out the app, spend extra time threat modeling, and be more careful in testing and in reviews.

Security Sprints

At some point later in development you may need to run a security Sprint or hardening Sprint – to get the app ready for release to production, or to deal with the results of a pen test or vulnerability scan or security audit, or to clean up after a security breach.

This could involve all or only some of the team. It might include reviewing and fixing vulnerabilities found in pen testing or scanning. Checking for vulnerabilities in third party and Open Source components and patching them. Working with ops to review and harden the run-time configuration. Updating and checking your incident response plan, or improving your code review or threat modeling practices, or reviewing and improving your security tests. Or all of the above.

Adding Security into Sprints. Just Do It.

Adding security into Sprints doesn’t have to be hard or cost a lot. A stripped down approach like this will take you a long way to building secure software. And if you want to dig deeper into how security can fit into Sprints, you can try out Microsoft’s SDL for Agile. Just do it.