CSRFGuard 2.2 ChangeLog
OWASP CSRFGuard 2.2 offers several advantages over previous releases. The purpose of this document is to briefly describe these changes and why they were required for a more robust and flexible implementation of a portable unique request token mechanism.
Detailed Change List
Developer Can Define Entry Point Pages
Consider the case when we have an unprotected page that links to a resource protected by CSRFGuard. That link on the unprotected page will not have the required unique request token to pass the CSRF defense. As a result, there were a number of false CSRF attacks detected in previous releases. To address this issue, the latest version of CSRFGuard allows the developer to define "entry point" pages. These are pages for which the existence of a token should never be validated but for which the token must always be inserted.
Developer Can Define Unprotected Pages
There are a number of scenarios why certain pages or resources should not be protected by OWASP CSRFGuard. In fact, fine-grain specification of protected resources can help overcome the overhead introduced through the use of CSRFGuard. Developers using the latest version of CSRFGuard can now specify pages that should not be protected. These pages are not validated for the existence of the token and they do not get the token inserted in their HTML.
Optionally Verify Token If Parameters Exist in the Request
Previous versions of CSRFGuard would validate every single request sent to a protected resource. Consider the case when you click the "Refresh" button or when you click a book mark. When these actions occur, no valid token will exist in the GET request. As a result, CSRFGuard will incorrectly detect an attack. To counter this issue, developers can configure OWASP CSRFGuard to only validate the request if there are one or more parameters in the request. If enabled, parameterless requests will not be validated by OWASP CSRFGuard. Please understand the potential consequences of this configuration. There are many web applications (Ex. Drupal, http://www.drupal.org) that invoke server-side actions using parameterless requests. If your application has this behavior, then I would highly recommend you consider not enabling this feature.
Developer Can Specify Initial Landing Page Upon Token Creation
Previous releases of OWASP CSRFGuard had a very innocuous bug that allowed for a one-time CSRF attack against a particular session. In previous versions, when the first request came in for a session, the token was created and the request (valid or forged!) would be allow through. As a result, there existed the possibility of performing a CSRF attack against an unauthenticated and session-less user. To counter this particular deficiency, developers can specify a "landing page" for the initial request when the CSRF token is being created. Rather than allowing the initial request through after token creation, the user can be optionally redirected to a safe landing page.
OWASP CSRFGuard Comes With a JSP Tag Library For Custom Token Insertion!
While I would love to take credit for this idea, in good conscience I cannot. A buddy of mine at the OWASP San Jose conference suggested the idea after I gave my talk about CSRFTester and CSRFGuard. I must say - it is an honor to be around so many smart people in this community!