Vulnerability Note VU#210876

Cisco PIX and ASA authentication bypass vulnerability

Original Release date: 02 May 2007 | Last revised: 15 Jun 2007


The Cisco ASA and PIX firewalls contain an authentication bypass vulnerability. This vulnerability may allow a remote attacker to gain unauthorized access to the internal network or firewall.


The Cisco Adaptive Security Appliance (ASA) is firewall that includes routing and intrusion prevention system (IPS) features. The Cisco PIX is a stateful firewall. The Cisco ASA and PIX firewalls include the ability to use LDAP and AAA servers to authenticate remote users or terminate VPN connections.

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.


A remote, unauthenticated attacker may be able to gain access to internal resources, or gain direct access to the firewall.


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 (Learn More)

VendorStatusDate NotifiedDate Updated
Cisco Systems, Inc.Affected-02 May 2007
If you are a vendor and your product is affected, let us know.

CVSS Metrics (Learn More)

Group Score Vector
Base N/A N/A
Temporal N/A N/A
Environmental N/A N/A



Thanks to Cisco for information that used in this report.

This document was written by Ryan Giobbi.

Other Information

  • CVE IDs: CVE-2007-2462
  • Date Public: 02 May 2007
  • Date First Published: 02 May 2007
  • Date Last Updated: 15 Jun 2007
  • Severity Metric: 2.43
  • Document Revision: 11


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