Home page logo
/

oss-sec logo oss-sec mailing list archives

Re: XSS hiding CSRF (was: Re: [oss-security] Mibew messenger multiple XSS)
From: Filippo Cavallarin <filippo.cavallarin () codseq it>
Date: Thu, 2 Feb 2012 10:28:02 +0100

I agree with you, this issues should have been categorized as CSRF. I had this doubt when reporting them and i decide 
to consider them XSS for one main reason: even with a CSRF protection an operator is still able to inject javascript 
into visitor's browser (ie an operator sets chat title to XSS and it gets executed when new visitor opens a chat). But 
propably you are rignt, there is no gain for an admin to exploit this and, for sure you are right, a password reset has 
a bigger impact.

Regards,
Filippo Cavallarin

On 2 Feb 2012, at 8:25 AM, Carsten Eiram wrote:

The points made by Steve are why we're spending so much time testing everything we can get our hands on. It's 
standard operating procedure - and has been for many years - to particularly pay attention to these "XSS hiding CSRF" 
cases. For that reason you'll often see discrepancies in the original report and the released Secunia advisories.

In the case of Mibew, the functionality is restricted to admins and from an administrator's perspective there is no 
gain. Therefore, we do not consider it a vulnerability in itself. However, via the CSRF vector it can be exploited by 
non-admins. This is why the Secunia advisory is rated as CSRF (like the OSVDB advisory) and just mentions XSS as a 
follow-up impact (along with alternatively just changing the administrator's password and gain full access that way).

I would definitely join Steve in encouraging researchers to keep this trend in mind by considering a) if a discovered 
issue actually provides a gain compared to legitimately accessible functionality and b) relies on another 
vulnerability in order to be an issue. We encounter these "XSS hiding CSRF" cases on a weekly basis.


-- 

Med venlig hilsen / Kind regards


Carsten H. Eiram
Chief Security Specialist

Follow us on twitter
http://twitter.com/secunia
http://twitter.com/carsteneiram

Secunia
Mikado House
Rued Langgaards Vej 8
2300 Copenhagen S
Denmark

Phone   +45 7020 5144
Fax       +45 7020 5145


-----Original Message-----
From: Steven M. Christey [mailto:coley () rcf-smtp mitre org]
Sent: 1. februar 2012 23:24
To: oss-security () lists openwall com
Cc: Henri Salo; filippo.cavallarin () codseq it
Subject: [oss-security] XSS hiding CSRF (was: Re: [oss-security] Mibew
messenger multiple XSS)


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.)

- Steve


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.

Advisory: http://seclists.org/bugtraq/2012/Jan/177
Codseq own advisory:
http://www.codseq.it/advisories/mibew_messenger_multiple_xss
OSVDB: http://osvdb.org/show/osvdb/78663
Secunia: http://secunia.com/advisories/47787/

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)





Filippo Cavallarin


C o d S e q
Development with an eye on security
------------------------------------------------------------------------
Castello 2005, 30122 Venezia
Tel: 041 88 761 58 - Fax: 041 81 064 714 - Cell: 346 66 93 254
c.f. CVLFPP82B27L736J - p.iva 03737650279
http://www.codseq.it - filippo.cavallarin () codseq it

Le informazioni contenute in questa e-mail e nei suoi eventuali allegati
sono confidenziali e riservate esclusivamente alle persone od enti a cui
sono destinate. Sono proibiti l'utilizzo per qualunque fine del presente
messaggio e di ogni documento ad esso allegato così come la relativa
divulgazione senza l'autorizzazione del mittente. Se avete ricevuto questa
e-mail per errore, vi preghiamo cortesemente di notificarlo (via e-mail,
fax, o telefono) al mittente e di distruggerla.
Tutti i messaggi elettronici sono suscettibili di alterazioni. I dati
personali sono trattati esclusivamente per le finalità della presente
comunicazione in conformità con la legislazione vigente (D.L. 196/2003
"Codice Privacy"). Informazioni: filippo.cavallarin () codseq it

This message and its attachments are addressed solely to the people or
entity above and may contain confidential information. If you have received
the message in error, be informed that any use of the content herein is
prohibited. Please return it immediately to he sender and delete the
message. E-mails are susceptible to alteration.
Should you have any questions, please contact us by replying to
filippo.cavallarin () codseq it


  By Date           By Thread  

Current thread:
[ Nmap | Sec Tools | Mailing Lists | Site News | About/Contact | Advertising | Privacy ]