Vulnerability Note VU#210876

Cisco PIX and ASA authentication bypass vulnerability

Per Cisco Security Advisory cisco-sa-20070502-asa:

Cisco ASA and PIX devices leveraging LDAP AAA servers for authentication of terminating L2TP IPSec tunnels or remote management sessions may be vulnerable to an authentication bypass attack. See the following bullets for more details:


• Layer 2 Tunneling Protocol (L2TP)
  Devices terminating L2TP IPSec tunnels must be configured to use LDAP in conjunction with CHAP, MS-CHAPv1, or MS-CHAPv2 authentication protocols to be vulnerable. If LDAP authentication is used in conjunction with PAP, the device is not vulnerable to the LDAP L2TP authentication bypass.
  
• Remote Management Access
  Cisco ASA and PIX devices leveraging LDAP AAA servers for authentication of management sessions (telnet, SSH and HTTP) may be vulnerable to an authentication bypass attack. Access for management sessions must be explicitly enabled and is limited to the defined source IP address within the device configuration.

Cisco has released an update to address this vulnerability. See the Software Versions and Fixes section of Cisco Security Advisory cisco-sa-20070502-asa for more details.

Restrict access

Restricting access to the firewall's telnet, SSH and HTTP interfaces to trusted hosts by using IP access control lists may mitigate this vulnerability.

Systems Affected

http://www.cisco.com/warp/public/707/cisco-sa-20070502-asa.shtml
http://www.cisco.com/en/US/products/ps6120/index.html
http://en.wikipedia.org/wiki/Intrusion-prevention_system
http://www.osvdb.org/35331

Credit

Thanks to Cisco for information that used in this report.

This document was written by Ryan Giobbi.

Other Information

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