Avoiding a Security Flaw in Your Java App [Code Snippet]
Avoiding a Security Flaw in Your Java App [Code Snippet]
Learn how to prevent malicious users from accessing a security hole that can be created when designing a child window exit in your app.
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Suppose you designed an app where the child window exits. Your user may close the child window by clicking the close button. You may, however, disable the window as read-only with setReadOnly to true as setReadOnly(true). You may also make it invisible with CSS display:none, but doing so means you have just created a security hole with the CSS key. This is because a malicious user can access the button and close the window. The best pratice is to set the window to read-only, which also prevents closing on the server side.
Here is an example of the use of a child window in an application using a custom component with open and close button:
class WindowHole extends CustomComponent implements Window.CloseListener {
Window mainwindow;
Window mywindow;
Button openbutton;
Button closebutton;
Label explanation;
public WindowHole(String label, Window main) {
mainwindow = main;
final VerticalLayout layout = new VerticalLayout();
openbutton = new Button("Open Window", this,"openButtonClick");
explanation = new Label("Explanation");
layout.addComponent(openbutton);
layout.addComponent(explanation);
setCompositionRoot(layout);
}
public void openButtonClick(Button.ClickEvent event) {
mywindow = new Window("My Dialog");
mywindow.setPositionX(200);
mywindow.setPositionY(100);
mainwindow.addWindow(mywindow);
mywindow.addListener(this);
mywindow.addComponent(new Label("A text label in the window."));
closebutton = new Button("Close", this, "closeButtonClick");
mywindow.addComponent(closebutton);
openbutton.setEnabled(false);
explanation.setValue("Window opened");
}
public void closeButtonClick(Button.ClickEvent event) {
mainwindow.removeWindow(mywindow);
openbutton.setEnabled(true);
explanation.setValue("Closed with button");
}
public void windowClose(CloseEvent e) {
openbutton.setEnabled(true);
explanation.setValue("Closed with window controls");
}
}
This example shows how we can inherit the CustomComponent class which consists of a button for the window opening and a label to show the attributes of the window.
Now you can see the window is open but the button is disabled. When the window is closed the button is enabled.
I hope this helps!
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Published at DZone with permission of Amuda Adeolu . See the original article here.
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