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
