CyberGuard proxy / firewall XSS

[Jamie Fisher <contact_jamie_fisher@xxxxxxxxxxx>]

Overview:

Vendor : CyberGuard
URL    : <A HREF="http://www.cyberguard.com";>http://www.cyberguard.com</A>
Version: 5.1 - Other versions have not been not tested
Issue  : Cross Site Script
Impact : Low - Medium

Description:

<A HREF="http://www.cyberguard.com/solutions/product_overview.cfm";>Overview of 
product</A>

Problem:

By issuing a GET request for an invalid Internet domain name <A 
HREF="http://domain.tld";>http://domain.tld</A> through the CyberGuard proxy 
from an internal network to the Internet, it is possible to append a basic 
syntax for a Cross Site Script...

For instance: <A 
HREF="http://domain.tld&lt;script&gt;alert('test')&lt;/script&gt;">Click 
here</A>.

Variants have been tested and it is possible to also include images on the 
error page.

For instance: it is possible to specify an image with the &lt;img src&gt; tag 
while also specifying a Cross Site Script - in the same address 
&lt;script&gt;alert('test')&lt;/script&gt;

Should you be 'vulnerable' to the CyberGuard proxy / firewall CSS then you 
should see a similar page or a variant depending on the configuaration.

As http (through the GUI) can be used as a mechanism whereby access to the the 
logs can be viewed, it may be possible for a miscreant to, through the usual 
obfuscation methods (encoding types) trick an administrator of the CyberGuard 
proxy / firewall into clicking on a Cross Site Script to gain privileged user 
credentials by specifying the (document.cookie) with a refer to a file where 
the user credentials can be collected for the purpose of executing by loading 
the credentials into the Achilies (or similar) proxy.

Note: this method of attack is yet untested.

Possible Solution:

Input validation of code executed on the CyberGuard proxy / firewall.
Configure the Cyberguard proxy / firewall so that management access can only be 
accessed via SSH.

Solution:

See Vendor for solution.

Vendor Notification:

Yes

Credit:

Everyone doing IT Security