BugTraq
CyberGuard proxy / firewall XSS Dec 18 2003 10:30AM
Jamie Fisher (contact_jamie_fisher yahoo co uk)


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<script>alert('test')</script>">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 <img src> tag while also specifying a Cross Site Script - in the same address <script>alert('test')</script>

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

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