Clear Skies Security Advisory

CSS10-01: Imperva SecureSphere Web Application Firewall and Database Firewall Bypass Vulnerability

April 5, 2010


The Imperva SecureSphere® Web Application Firewall protects web applications and sensitive data against sophisticated attacks and brute force attacks, stops online identity theft, and prevents data leaks from applications. The Imperva SecureSphere Database Firewall monitors and proactively protects databases from internal abuse, database attacks, and unauthorized activity.  (Source:


Imperva SecureSphere Web Application Firewall and Database Firewall products can be bypassed by appending specially crafted data to requests. Protection provided by the Imperva device against attacks such as SQL injection and Cross-Site Scripting is negated, allowing unfiltered requests through to protected applications.


Rating:   High Risk - CVSS 7.8 (AV:N/AC:L/Au:N/C:N/I:C/A:N) 
Impact:  Bypass security control 
Where:   Remote


An attacker can use this flaw to bypass firewall protections. Anyone with the ability to interact with protected web applications and databases can exploit this vulnerability. Only minimal skill is required and the bypass can be incorporated into existing exploitation frameworks and security testing tools. Exploitation of this issue does not permanently affect the device; each evasion request must contain the bypass payload.


Administrators can identify the current version in use by going to the Licensing menu in the administration console. Versions less than those identified in the Solutions section below are vulnerable.


The Imperva device provides no indication when this vulnerability is exploited. If other controls are in place such as network traffic monitors, IDS/IPS, or web filters, these should be configured to alert on payloads containing attack patterns.


This vulnerability affects SecureSphere G-series and Database Firewalls running versions the Web Application and Database Firewall product prior to March 9, 2010. This includes all versions of SecureSphere from 5.0 through 7.0.


The vendor has released patches for affected versions to address this issue. Customers are strongly encouraged to apply the update as soon as possible. Refer to for upgrade instructions. No reliable workaround is available.

The vendor has provided the following version and patch data:


Patch Number

Patch 11

Patch 11

Patch 24

Patch 24

Patch 30

Patch 30

Patch 30

Patch 30

Patch 30

Patch 30 on XOS 8.0/5

ssgw-6128-CBI10 on XOS 8.5.3





2009-08-31 – Vendor notified. 
2010-03-09 – Vendor released patched firmware. 
2010-04-05 – Public notification


Scott Miles and Greag Johnson, Clear Skies Security, identified this flaw.

Clear Skies would like to thank Mike Sanders and Accuvant Labs for their assistance in clarifying and working with the vendor to correct this issue.


Disclaimer: The information in the advisory is believed to be accurate at the time of publishing and is subject to change without notice. Use of the information constitutes acceptance for use in an AS IS condition. There are no warranties with regard to this information. The author is not liable for any direct, indirect, or consequential loss or damage arising from use of, or reliance on, this information.

Copyright © 2010 Clear Skies Security, LLC.

Permission is granted for the redistribution of this alert electronically. It may not be edited in any way without the express written consent of Clear Skies Security. To reprint this alert, in whole or in part, in any other medium other than electronically, please e-mail info (at) clearskies (dot) net for permission.