Cisco Adaptive Security Appliance Remote Code Execution and Denial of Service Vulnerability

A vulnerability in the Secure Sockets Layer (SSL) VPN functionality of the Cisco Adaptive Security Appliance (ASA) Software could allow an unauthenticated, remote attacker to cause a reload of the affected system or to remotely execute code.

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.

Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.

CVE Number – CVE-2018-0101

This advisory is available at the following link:

Affected Products
  • Vulnerable Products

    This vulnerability affects Cisco ASA Software that is running on the following Cisco products:

    • 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)


    ASA Software

    This vulnerability affects devices that are running a vulnerable release of Cisco ASA Software where the webvpn feature is enabled. In addition to webvpn being globally configured there must be one enabled interface via the enable <if_name> in the configuration. To determine whether webvpn is enabled for at least one interface, administrators can use the show running-config webvpn command at the CLI and verify that the command returns at least one enable <if_name> line.

    ASA Software

    8.x       Migrate to or later

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    9.9       Migrate to or later

Duncan Newell

Duncan is a technology professional with over 20 years experience of working in various IT roles. He has a interest in cyber security, and has a wide range of other skills in radio, electronics and telecommunications.

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