CSIRTUK advisories

ID: 3912
Date: 02/12/2009

---

Title: 3912 - Clientless SSL VPN products break browser security models
Other software: Web Browser
Remediation Summary:CPNI are monitoring the situation and will publish further advice if the risks change.
Adversity source: Unknown
Attack Vector: Vulnerability exploitation
Virulence: Unknown
Warning Status: Unknown
Potential Damage: Remote execution/modification
Possible Duration: Unknown
Availability of fix: Future
Type of fix: None
Source: USCERT
Reliability of source: Trusted
Source URL: http://www.kb.cert.org/vuls/id/261869
Abstract: Clientless SSL VPN products break web browser domain-based security models

Clientless SSL VPN products from multiple vendors operate in a way that breaks fundamental browser security mechanisms. An attacker could use these devices to bypass authentication or conduct other web-based attacks. By convincing a user to view a specially crafted web page, a remote attacker may be able to obtain VPN session tokens and read or modify content (including cookies, script, or HTML content) from any site accessed through the clientless SSL VPN. Because all content runs at the privilege level of the web VPN domain, mechanisms to provide domain-based content restrictions, such as Internet Explorer security zones and the Firefox add-on NoScript, may be bypassed.

For further information please refer to US-CERT's advisory at http://www.kb.cert.org/vuls/id/261869.

This advisory contains information released by the original author. Some of the information may have changed since it was released. If the issue affects you, it may be prudent to retrieve the advisory from the site of the original source to ensure that you receive the most current information concerning that problem. Reference to any specific commercial product, process, or service by trade name, trademark manufacturer, or otherwise, does not constitute or imply its endorsement, recommendation, or favouring by CPNI.

The views and opinions of authors expressed within this notice shall not be used for advertising or product endorsement purposes. CPNI shall not accept responsibility for any errors or omissions contained within this advisory. In particular, they shall not be liable for any loss or damage whatsoever, arising from or in connection with the usage of information contained within this advisory.

CSIRTUK is a member of the Forum of Incident Response and Security Teams (FIRST) and has contacts with other international Incident Response Teams (IRTs) in order to foster cooperation and coordination in incident prevention, to prompt rapid reaction to incidents, and to promote information sharing amongst its members and the community at large.