Multiple vulnerabilities exist in the Cisco ASA 5500 Series Adaptive Security Appliances and Cisco PIX Security Appliances. This security advisory outlines details of these vulnerabilities:

Windows NT Domain Authentication Bypass Vulnerability

IPv6 Denial of Service Vulnerability

Crypto Accelerator Memory Leak Vulnerability



Vulnerable Products

Windows NT Domain Authentication Bypass Vulnerability

Because of a Microsoft Windows NT Domain authentication issue the Cisco ASA and Cisco PIX devices may be susceptible to a VPN authentication bypass vulnerability. Cisco ASA or Cisco PIX security appliances that are configured for IPSec or SSL-based remote access VPN using Microsoft Windows NT Domain authentication may be vulnerable. Devices that are using any other type of external authentication (that is, LDAP, RADIUS, TACACS+, SDI, or local database) are not affected by this vulnerability.

IPv6 Denial of Service Vulnerability

Cisco ASA and Cisco PIX security appliances that are running software version 7.2(4)9 or 7.2(4)10 and configured for IPv6 may be vulnerable. This vulnerability does not affect devices configured only for IPv4. Note: IPv6 functionality is turned off by default.

Crypto Accelerator Memory Leak Vulnerability

Cisco ASA security appliances may experience a memory leak that can be triggered by a series of crafted packets. This memory leak occurs in the initialization code for the hardware crypto accelerator. Devices that are running software versions in the 8.0.x release are vulnerable.

Note: Cisco ASA appliances that are running software versions in the 7.0, 7.1, and 7.2 releases are not vulnerable. The Cisco PIX security appliance is not affected by this vulnerability.

Details

This Security Advisory describes multiple distinct vulnerabilities. These vulnerabilities are independent of each other.

Windows NT Domain Authentication Bypass Vulnerability

Because of a Microsoft Windows NT Domain authentication issue the Cisco ASA and Cisco PIX devices may be susceptible to a VPN authentication bypass vulnerability. Cisco ASA or Cisco PIX security appliances configured for IPSec or SSL-based remote access VPN may be vulnerable.

Note: Cisco ASA or Cisco PIX security appliances that are configured for IPSec or SSL-based remote access VPN using any other type of external authentication (that is, LDAP, RADIUS, TACACS+, SDI, or local database) are not affected by this vulnerability.

The Cisco ASA security appliance supports Microsoft Windows server operating systems that support NTLM version 1, collectively referred to as “NT servers”. NT Domain authentication is supported only for remote access VPNs.

This vulnerability is documented in Cisco Bug ID CSCsu65735 ( registered customers only) and has been assigned Common Vulnerabilities and Exposures (CVE) identifiers CVE-2008-3815.

IPv6 Denial of Service Vulnerability

A specially crafted IPv6 packet may cause the Cisco ASA and Cisco PIX security appliances to reload. Devices that are running software version 7.2(4)9 or 7.2(4)10 and configured for IPv6 may be vulnerable. This vulnerability does not affect devices that are configured only for IPv4.

Note: Devices that are running software versions in the 7.0, 7.1, 8.0, and 8.1 releases are not vulnerable.

To configure IPv6 on a Cisco ASA or Cisco PIX security appliance, at a minimum, each interface needs to be configured with an IPv6 link-local address. Additionally, you can add a global address to the interface.

Note: Only packets that are destined to the device (not transiting the device) may trigger the effects of this vulnerability. These packets must be destined to an interface configured for IPv6.

This vulnerability is documented in Cisco Bug ID CSCsu11575 ( registered customers only) and has been assigned Common Vulnerabilities and Exposures (CVE) identifier CVE-2008-3816.

Crypto Accelerator Memory Leak Vulnerability

The Cisco ASA security appliances may experience a memory leak triggered by a series of packets. This memory leak occurs in the initialization code for the hardware crypto accelerator.

Note: Only packets destined to the device (not transiting the device) may trigger this vulnerability.

The following Cisco ASA features use the services the crypto accelerator provides, and therefore may be affected by this vulnerability:

Clientless WebVPN, SSL VPN Client, and AnyConnect Connections

ASDM (HTTPS) Management Sessions

Cut-Through Proxy for Network Access

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TLS Proxy for Encrypted Voice Inspection

IP Security (IPsec) Remote Access and Site-to-site VPNs

Secure Shell (SSH) Access

Impact

Successful exploitation of the VPN Authentication Bypass Vulnerability may allow an attacker to successfully connect to the Cisco ASA via remote access IPSec or SSL-based VPN. The Denial of Service (DoS) vulnerabilities may cause a reload of the affected device. Repeated exploitation could result in a sustained DoS condition.

More info on http://www.cisco.com/…/products_security_advisory09186a0080a183ba.shtml