XWiki Platform is a generic wiki platform. Starting in version 13.9-rc-1 and prior to versions 4.10.19, 15.5.4, and 15.10-rc-1, when the realtime editor is installed in XWiki, it allows arbitrary remote code execution with the interaction of an admin user with programming right. More precisely, by getting an admin user to either visit a crafted URL or to view an image with this URL that could be in a comment, the attacker can get the admin to execute arbitrary XWiki syntax including scripting macros with Groovy or Python code. This compromises the confidentiality, integrity and availability of the whole XWiki installation. This vulnerability has been patched in XWiki 14.10.19, 15.5.4 and 15.9. As a workaround, one may update RTFrontend.ConvertHTML manually with the patch. This will, however, break some synchronization processes in the realtime editor, so upgrading should be the preferred way on installations where this editor is used.
Weakness
The web application does not, or can not, sufficiently verify whether a well-formed, valid, consistent request was intentionally provided by the user who submitted the request.
Potential Mitigations
- Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
- For example, use anti-CSRF packages such as the OWASP CSRFGuard. [REF-330]
- Another example is the ESAPI Session Management control, which includes a component for CSRF. [REF-45]
- Use the “double-submitted cookie” method as described by Felten and Zeller:
- When a user visits a site, the site should generate a pseudorandom value and set it as a cookie on the user’s machine. The site should require every form submission to include this value as a form value and also as a cookie value. When a POST request is sent to the site, the request should only be considered valid if the form value and the cookie value are the same.
- Because of the same-origin policy, an attacker cannot read or modify the value stored in the cookie. To successfully submit a form on behalf of the user, the attacker would have to correctly guess the pseudorandom value. If the pseudorandom value is cryptographically strong, this will be prohibitively difficult.
- This technique requires Javascript, so it may not work for browsers that have Javascript disabled. [REF-331]
References