SecurityReason - Webwasher Denial of Service Vulnerability

Advisory Text :

Credit: The disclosure of this issue has been credited to National
Australia Bank Security

Assurance.

Vulnerable:

Secure Computing Webwasher 6.6.3 build 3102 and older versions running on
CGLinux 4/5, RHEL 4, Debian 4, SLES10

Not vulnerable:

Secure Computing Webwasher Builds 3150 and newer (all platforms)

Webwasher (all versions) for Windows

Webwasher (all versions) for Solaris

Webwasher (all versions) for some Linux (RHEL 3, SLES8, SLES9, Debian 3)

Webwasher 5.3 appliances (running CGLinux 3.x)

DISCUSSION

Due to a change in the behavior of newer Linux systems, we have become
aware that a Denial of Service attack can be launched against Webwasher
running on Linux based operating systems which will freeze the Webwasher
service. If this happens, Webwasher becomes unable to handle any request
until the Webwasher service is restarted.

The attack can be initiated by an internal user sending a specially crafted
URL to Webwasher. It could also be exploited by an external attacker by
redirecting proxy users to the exploit URL.

Who is affected?

Users of all Webwasher appliances version 6.x (CGLinux 4 or 5):

?If not running current version of Webwasher software but build numbers
prior to 3150

Users of Webwasher software versions

?If running on RedHat Enterprise Linux 4, Debian Linux 4 or Linux Suse
Linue 10

?And if not running current version of Webwasher software but build numbers
prior to 3150

Who is not affected?

?All Webwasher installations on current versions ? build numbers 3150 or
newer

?Webwasher Software customers on Windows, Solaris, Linux RedHat Enterprise
3, Linux Suse 8 and 9, Debian 3.1 and Webwasher appliances running with
CGLinux 3.x are not affected.

EXPLOIT

A special handcrafted URL has to be sent to Webwasher on the affected Linux
systems which will then freeze the application.

National Australia Bank Security Assurance has provided an undisclosed
proof of concept.

SOLUTION

The vendor has released Webwasher versions to address this:

?Webwasher 6.6.3 build 3150

?Webwasher 5.3.0 build 3159

Both are available at:
https://extranet.webwasher.com/download/csm/index.html

Webwasher appliances can be upgraded automatically via the GUI