Affected product
----------------

Sourcefire 3D Sensor and Defense Center 4.8.x
 
Tested on 4.8.0.3 and 4.8.0.4, 3D Sensor 2500 & DC 1000
All 4.8.x releases, up to and including 4.8.1, confirmed vulnerable by sourcefire.


Vulnerability details
---------------------

A privilege escalation vulnerability found in the Sensor and the DC web based management interfaces allows any local account
to take over the appliances administrator role.
While the "user.cgi" PERL script correctly validates that incoming requests belong to an authenticated session, in such a case 
it also blindly grants read/write access to all accounts configuration with no regard for the role of the request's originator. 
Therefore a user with even the lowest level of access (ie. without any role configured) is able to promote himself as administrator 
and/or change others roles and account parameters at will. 
Depending of the role or roles initially configured for this user, access to the user management page may not be visible
into the interface's layout however the underlying script itself is still reachable and can be invoked "by hand".

Let's now consider a malicious operator named 'foobar' whose role has been restricted to "Event analyst (read only)".
He would first log in to the appliance using his own credentials in order to get an authenticated session cookie (CGISESSID=xxxxxxxxxxxxxxxxxx)
then he could send a forged POST request similar to the one below:
 
POST https://x.x.x.x/admin/user/user.cgi HTTP/1.1
User-Agent: xxxxxx
Keep-Alive: 300
Connection: Keep-alive
Cookie: CGISESSID=xxxxxxxxxxxxxxxxxx
Content-Type: application/x-www-form-urlencoded
Content-length: 56

mode=edit&username=foobar&admin=%24admin&action_add=Save

He would thereafter be promoted to administrator by the appliance with full access into the management interface.
 
As a final note, several other scripts were reported being affected by the same vulnerability after investigation from the vendor.


Resolution
----------

Upgrade your appliance's software to 4.8.2 available from the Sourcefire's support website located at https://support.sourcefire.com/


Disclosure timeline
-------------------

2009-05-05: Vulnerability discovered and reported to Sourcefire.
2009-06-30: 4.8.2 released by Sourcefire.
2009-07-01: Public disclosure.



Gregory Duchemin