Impact
Any registered user can exploit a stored XSS through their user profile by setting the payload as the value of the time zone user preference. Even though the time zone is selected from a drop down (no free text value) it can still be set from JavaScript (using the browser developer tools) or by calling the save URL on the user profile with the right query string. Once the time zone is set it is displayed without escaping which means the payload gets executed for any user that visits the malicious user profile, allowing the attacker to steal information and even gain more access rights (escalation to programming rights).
The problem is present since version 4.1M2 when the time zone user preference was introduced.
Patches
The issue has been fixed in XWiki 14.10.5 and 15.1RC1 by d11ca5d . The main fix is in the displayer_timezone.vm precisely at this line:
By escaping the displayed time zone value we make sure the attacker's payload is not executed.
Workarounds
If you want to fix this problem on older versions of XWiki that have not been patched then you need to edit displayer_timezone.vm and escape the displayed time zone value here:
- $!value
+ $!escapetool.xml($value)
References
For more information
If you have any questions or comments about this advisory:
Attribution
This vulnerability has been found and reported by @michitux .
Impact
Any registered user can exploit a stored XSS through their user profile by setting the payload as the value of the time zone user preference. Even though the time zone is selected from a drop down (no free text value) it can still be set from JavaScript (using the browser developer tools) or by calling the save URL on the user profile with the right query string. Once the time zone is set it is displayed without escaping which means the payload gets executed for any user that visits the malicious user profile, allowing the attacker to steal information and even gain more access rights (escalation to programming rights).
The problem is present since version 4.1M2 when the time zone user preference was introduced.
Patches
The issue has been fixed in XWiki 14.10.5 and 15.1RC1 by d11ca5d . The main fix is in the
displayer_timezone.vmprecisely at this line:By escaping the displayed time zone value we make sure the attacker's payload is not executed.
Workarounds
If you want to fix this problem on older versions of XWiki that have not been patched then you need to edit
displayer_timezone.vmand escape the displayed time zone value here:References
For more information
If you have any questions or comments about this advisory:
Attribution
This vulnerability has been found and reported by @michitux .