Cisco Security Advisory: LDAP and VPN Vulnerabilities in PIX and ASA Appliances
Author: Dave Lewis
Just noticed this one, thought I would share. This is a security bypass and a DoS vuln.
Summary
Multiple vulnerabilities exist in the Cisco Adaptive Security Appliance (ASA) and PIX security appliances. These vulnerabilities include two Lightweight Directory Access Protocol (LDAP) authentication bypass vulnerabilities and two denial of service (DoS) vulnerabilities.
The Lightweight Directory Access Protocol (LDAP) authentication bypass vulnerabilities are caused by a specific processing path followed when the device is setup to use a Lightweight Directory Access Protocol (LDAP) authentication server. These vulnerabilities may allow unauthenticated users to access either the internal network or the device itself.
The two DoS vulnerabilities may be triggered when devices are terminating Virtual Private Networks (VPN). These denial of service vulnerabilities may allow an attacker to disconnect VPN users, prevent new connections, or prevent the device from transmitting traffic.
These vulnerabilities are distributed in the authentication, IPSec VPN, and SSL VPN code. They are categorized in this advisory by their Cisco bug descriptions:
* LDAP Authentication Bypass
* Denial of Service in VPNs with Password Expiry
* Denial of Service in SSL VPNsCisco has made free software available to address these vulnerabilities for affected customers.
And here is the Secunia write up on this one:
Description:
Some vulnerabilities have been reported in Cisco PIX and ASA, which can be exploited by malicious people to bypass certain security restrictions or cause a DoS (Denial of Service).1) An unspecified error exists when using the LDAP authentication mechanism, which can be exploited to bypass the authentication and gain access to the device or the network.
Successful exploitation requires that the device uses the Layer 2 Tunneling Protocol (L2TP) and is configured to use LDAP servers with another protocol other than PAP for authentication, or that the device offers remote management access (telnet, SSH, HTTP) and uses an LDAP AAA server for authentication.
2) An unspecified error when using VPN connections configured with password expiry can be exploited to cause a DoS.
Successful exploitation requires that the tunnel group is configured with password expiry. In order to exploit this in IPSec VPN connections, an attacker also needs to know the group name and group password.
3) A race condition within the processing of non-standard SSL sessions in the SSL VPN server of Cisco ASA appliances can be exploited to cause the device to reload.
Successful exploitation requires that clientless SSL is used.
4) An error within the DHCP relay agent when handling DHCPACK messages can be exploited to cause a DoS due to memory exhaustion by sending a large number of DHCP requests to a vulnerable device.
Successful exploitation requires that devices are configured to use the DHCP relay agent.
Solution:
Apply updated software versions. Please see vendor advisories for details.
Tags: Cisco Security, Cisco LDAP Vulnerability, Cisco VPN Vulnerability
