Cisco Response
Additional Information
Revision History
Cisco Security Procedures
This is Cisco PSIRT's response to the statements made by George Gal in his advisory: WebSense Content Filter Bypass in conjunction with Cisco PIX in packet filter mode, posted on May 08, 2006.
The original email/advisory is available at
http://www.vsecurity.com/bulletins/advisories/2006/cisco-websense-bypass.txt
.
This issue is being tracked by Cisco Bug IDs:
We would like to thank George Gal of Virtual Security Research for reporting this issue to us.
We greatly appreciate the opportunity to work with researchers on security vulnerabilities, and welcome the opportunity to review and assist in product reports.
If various PIX/ASA/FWSM software versions are configured to use Websense/N2H2 for content filtering, users may be able to bypass HTTP content restrictions. By fragmenting the GET method of an HTTP request into multiple packets, it is possible to cause a condition in which the PIX/ASA/FWSM firewall will mistakenly allow a restricted website to be accessed. The PIX/ASA/FWSM firewall expects the entire GET method to be received in one packet. There are no workarounds which mitigate or eliminate this issue.
PIX software version 6.3.5(112) and later resolves this issue. Interim releases of PIX 6.3 software are only available by contacting the Cisco TAC or your Cisco support partner. Please reference this security response when requesting software to ensure the proper software version is obtained.
PIX/ASA software versions 7.0(5) and 7.1(2) resolve this issue. Maintenance releases of PIX/ASA 7.x software may be downloaded at the following sites.
http://www.cisco.com/pcgi-bin/tablebuild.pl/pix?psrtdcat20e2
http://www.cisco.com/pcgi-bin/tablebuild.pl/asa?psrtdcat20e2
FWSM software versions 2.3(4), 3.1(1.7) and later resolve this issue. FWSM software version 2.3(4) may be downloaded at the following site.
http://www.cisco.com/pcgi-bin/tablebuild.pl/cat6000-fwsm?psrtdcat20e2
Interim releases of FWSM 3.1 software are only available by contacting the Cisco TAC or your Cisco support partner. Please reference this security response when requesting software to ensure the proper software version is obtained.
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1.0 |
2006-May-08 |
Initial public release. |
Complete information on reporting security vulnerabilities in Cisco products, obtaining assistance with security incidents, and registering to receive security information from Cisco, is available on Cisco's worldwide website at http://www.cisco.com/warp/public/707/sec_incident_response.shtml. This includes instructions for press inquiries regarding Cisco security notices. All Cisco security advisories are available at http://www.cisco.com/go/psirt.
| Updated: May 08, 2006 | Document ID: 70090 |