mailing list archives
XSS hiding CSRF (was: Re: [oss-security] Mibew messenger multiple XSS)
From: "Steven M. Christey" <coley () rcf-smtp mitre org>
Date: Wed, 1 Feb 2012 17:23:34 -0500 (EST)
Funny, the CVE team was discussing this curiosity just today.
In the Mibew case, the PoC code has POST forms that invoke scripts like
"/operator/ban.php" and "/operator/settings.php". These are almost
certainly administrative functions that probably shouldn't be reachable at
all. Thus, these might be better identified as CSRF issues at their core,
instead of XSS.
It seems that some researchers report XSS in administrator modules, but
they omit when you need to use CSRF in order to get the administrator to
perform the XSS. So, the primary issue is often CSRF, and XSS is only
resultant (since, in many cases, the admin already has privileges to edit
HTML). The vuln DBs are starting to catch up with this "trend" in vuln
reporting, so there is a very slow shift towards identifying CSRF as the
core problem. However, CSRF is in the eye of the beholder, in that you
often need to know the INTENDED functionality of the application before
you can interpret whether things are CSRF versus regular functionality,
versus good old XSS.
Note that this kind of XSS-hiding-CSRF issue is not necessarily tied to
admin functionality, but that's where it's a strong indicator that a
researcher might be ignoring CSRF.
Sometimes, though, it can be difficult to determine whether XSS or CSRF is
at the root, even if you're dealing with admin functionality. For
example, maybe an admin program will check for CSRF and fail, but include
the original form in its error response, possibly enabling XSS. Or, maybe
there are TWO issues at play - maybe a victim can be CSRF'ed to make posts
on their behalf, and also a secondary issue where the victim can become an
attacker and XSS other people (with or without CSRF).
Unfortunately, I strongly suspect that the number of XSS-hiding-CSRF
reports will grow :-(
For people who investigate vuln reports closely, please keep this trend in
mind. If you are a researcher, consider whether XSS or other issues are
really legitimate functionality that is only reachable by targeting the
victim with CSRF; if that's the case, then the CSRF is "primary" and the
XSS is "resultant" and not a separate vulnerability - and if your targeted
application has CSRF, then maybe there's a more powerful impact than just
XSS. (For example, depending on how settings / configuration is
implemented, you might be able to get code execution out of it.)
On Wed, 1 Feb 2012, Kurt Seifried wrote:
On 01/31/2012 08:22 AM, Henri Salo wrote:
This seems to need 2012 CVE-identifier.
Codseq own advisory: http://www.codseq.it/advisories/mibew_messenger_multiple_xss
At the moment http://mibew.org/ does not work for me.
- Henri Salo
Please use CVE-2012-0829 for this issue.
P.S. for some reason OSVDB lists this as a CSRF issue (?) which is
mentioned in the advisory but not really shown.
Kurt Seifried Red Hat Security Response Team (SRT)