XWiki CKEditor.HTMLConverter vulnerable to Remote Code Execution via Cross-Site Request Forgery

Impact

The CKEditor.HTMLConverter document lacked a protection against Cross-Site Request Forgery (CSRF), allowing to execute macros with the rights of the current user. If a privileged user with programming rights was tricked into executing a GET request to this document with certain parameters (e.g., via an image with a corresponding URL embedded in a comment or via a redirect), this would allow arbitrary remote code execution and the attacker could gain rights, access private information or impact the availability of the wiki.

The attack can be demonstrated by accessing the URL <server>/xwiki/bin/view/Main?sheet=CKEditor.HTMLConverter&language=en&sourceSyntax=xwiki%2F2.1&stripHTMLEnvelope=true&fromHTML=false&toHTML=true&text=%7B%7Bgroovy%7D%7Dprintln%28%22Hello+from+Groovy%21%22%29%7B%7B%2Fgroovy%7D%7D where <server> is the URL of the XWiki installation as a user with programming rights. If this displays the text "Hello from Groovy!", the installation is vulnerable.

Patches

The issue has been patched in the CKEditor Integration version 1.64.3. This has also been patched in the version of the CKEditor integration that is bundled starting with XWiki 14.6 RC1.

Workarounds

There are no known workarounds for this other than upgrading the CKEditor integration to a fixed version.

References

• https://github.com/xwiki-contrib/application-ckeditor/commit/6b1053164386aefc526df7512bc664918aa6849b
• https://jira.xwiki.org/browse/CKEDITOR-475

For more information

If you have any questions or comments about this advisory:

• Open an issue in Jira XWiki.org
• Email us at Security Mailing List