Critical Security Issue Found in Cisco VPNs

A critical security vulnerability was recently discovered in the Secure Sockets Layer (SSL) VPN functionality of the Cisco Adaptive Security Appliance (ASA) Software.

An advisory has been published by Cisco which contains details of the software updates released that address this vulnerability. There are no workarounds.

The vulnerability could allow an unauthenticated, remote attacker to cause a reload of the affected system - or to remotely execute code.

The following products running Cisco ASA Software are affected:

• 3000 Series Industrial Security Appliance (ISA)
• ASA 5500 Series Adaptive Security Appliances
• ASA 5500-X Series Next-Generation Firewalls
• ASA Services Module for Cisco Catalyst 6500 Series Switches and Cisco 7600 Series Routers
• ASA 1000V Cloud Firewall
• Adaptive Security Virtual Appliance (ASAv)
• Firepower 2100 Series Security Appliance
• Firepower 4110 Security Appliance
• Firepower 9300 ASA Security Module
• Firepower Threat Defense Software (FTD)

Cisco's critical advisory states: "The vulnerability is due to an attempt to double free a region of memory when the webvpn feature is enabled on the Cisco ASA device. An attacker could exploit this vulnerability by sending multiple, crafted XML packets to a webvpn-configured interface on the affected system. An exploit could allow the attacker to execute arbitrary code and obtain full control of the system, or cause a reload of the affected device."

Customers with a valid support contract will be able to download the software directly from Cisco via this link. Those without contracts are also able to obtain the upgrade via Cisco TAC as detailed in the advisory.