Cisco VPN3K/ASA WebVPN Clientless Mode Cross-Site Scripting Vulnerability

Bugtraq ID:	18419
Class:	Input Validation Error
CVE:
Remote:	Yes
Local:	No
Published:	Jun 14 2006 12:00AM
Updated:	Jan 26 2007 04:09PM
Credit:	Discovery is credited to Michal Zalewski.
Vulnerable:	Cisco VPN 3000 Concentrator 4.7.1 F Cisco VPN 3000 Concentrator 4.7.1 Cisco VPN 3000 Concentrator 4.7 Cisco VPN 3000 Concentrator 4.1.5 .B Cisco VPN 3000 Concentrator 4.1 .x Cisco VPN 3000 Concentrator 4.0.5 .B Cisco VPN 3000 Concentrator 4.0.1 Cisco VPN 3000 Concentrator 4.0 .x Cisco VPN 3000 Concentrator 4.0 Cisco VPN 3000 Concentrator 3.6.7 D Cisco VPN 3000 Concentrator 3.6.7 Cisco VPN 3000 Concentrator 3.6.1 Cisco VPN 3000 Concentrator 3.6 Cisco VPN 3000 Concentrator 3.5.5 Cisco VPN 3000 Concentrator 3.5.4 Cisco VPN 3000 Concentrator 3.5.3 Cisco VPN 3000 Concentrator 3.5.2 Cisco VPN 3000 Concentrator 3.5.1 Cisco VPN 3000 Concentrator 3.5 (Rel) Cisco VPN 3000 Concentrator 3.1.4 Cisco VPN 3000 Concentrator 3.1.2 Cisco VPN 3000 Concentrator 3.1.1 Cisco VPN 3000 Concentrator 3.1 (Rel) Cisco VPN 3000 Concentrator 3.1 Cisco VPN 3000 Concentrator 3.0.4 Cisco VPN 3000 Concentrator 3.0.3 (B) Cisco VPN 3000 Concentrator 3.0.3 (A) Cisco VPN 3000 Concentrator 3.0 Cisco VPN 3000 Concentrator 3.0 Cisco VPN 3000 Concentrator 2.5.2 (F) Cisco VPN 3000 Concentrator 2.5.2 (D) Cisco VPN 3000 Concentrator 2.5.2 (C) Cisco VPN 3000 Concentrator 2.5.2 (B) Cisco VPN 3000 Concentrator 2.5.2 (A) Cisco VPN 3000 Concentrator 2.0 Cisco VPN 3000 Concentrator 4.1.7.B Cisco VPN 3000 Concentrator 4.1.7.A Cisco ASA 5500 Series Adaptive Security Appliance 7.0.4 .3 Cisco ASA 5500 Series Adaptive Security Appliance 7.0.4 Cisco ASA 5500 Series Adaptive Security Appliance 7.0
Not Vulnerable:

Cisco VPN3K/ASA WebVPN Clientless Mode Cross-Site Scripting Vulnerability

Cisco VPN 3000 Series Concentrators and ASA 5500 Series Adaptive Security Appliances (ASA) are prone to cross-site scripting attacks via the WebVPN Clientless Mode.

The issue is due to insufficient sanitization of HTML and script code from error messages that are displayed to users. This vulnerability could result in the execution of attacker-supplied HTML and script code in the session of a victim user. In the worst-case scenario, the attacker could gain unauthorized access to the VPN by stealing the WebVPN session cookie.

Cisco tracks this issue as Bug IDs CSCsd81095 and CSCse48193.

Update: Cisco states that WebVPN full-network-access mode is not affected by this issue.

Cisco VPN3K/ASA WebVPN Clientless Mode Cross-Site Scripting Vulnerability

This issue can be exploited by enticing an authenticated VPN user to visit a URI that contains embedded HTML and script code. The URI will cause the malicious code to be rendered in the 'dnserror.html' or 'connecterror.html' error pages.

Cisco VPN3K/ASA WebVPN Clientless Mode Cross-Site Scripting Vulnerability

Solution:
Cisco has addressed this issue. Users of affected software should contact the vendor for information on obtaining and applying fixes.

Cisco VPN3K/ASA WebVPN Clientless Mode Cross-Site Scripting Vulnerability

References:

• WebVPN Cross-Site Scripting Vulnerability (Cisco)
  
• SSL VPNs and security (Michal Zalewski )