Cisco AnyConnect Secure Mobility Client Arbitrary Code Execution Vulnerability

DESCRIPTION
A vulnerability in the interprocess communication (IPC) channel of Cisco AnyConnect Secure Mobility Client Software could allow an authenticated, local attacker to cause a targeted AnyConnect user to execute a malicious script.

The vulnerability is due to a lack of authentication to the IPC listener. An attacker could exploit this vulnerability by sending crafted IPC messages to the AnyConnect client IPC listener. A successful exploit could allow an attacker to cause the targeted AnyConnect user to execute a script. This script would execute with the privileges of the targeted AnyConnect user.

Note: To successfully exploit this vulnerability, an attacker would need all of the following:

    • Valid user credentials on the system on which the AnyConnect client is being run by the targeted user.
    • To be able to log in to that system while the targeted user either has an active AnyConnect session established or establishes a new AnyConnect session.
    • To be able to execute code on that system.

Cisco has not released software updates that address this vulnerability. There are workarounds that address this vulnerability.

SYSTEM AFFECTED
    • AnyConnect Secure Mobility Client for Windows
    • AnyConnect Secure Mobility Client for MacOS
    • AnyConnect Secure Mobility Client for Linux

RECOMMENDATIONS

Following actions are recommended to be taken:
Workarounds that address this vulnerability were introduced in Defect CSCvw48062.

The recommended workaround is to upgrade to Release 4.9.04053 and edit the AnyConnectLocalPolicy.xml file to set RestrictScriptWebDeploy to true. Ensure that BypassDownloader is set to false. The new AnyConnectLocalPolicy.xml file would then be deployed to end machines using an out-of-band method of deployment.

There are additional configuration settings for Release 4.9.04053 and later that are strongly recommended to be set for increased protection. The full set of custom web-deploy restrictions are listed below. For more details on the new configuration settings and implications of their use, refer to the Release Notes or CSCvw48062.

    • RestrictScriptWebDeploy
    • RestrictHelpWebDeploy
    • RestrictResourceWebDeploy
    • RestrictLocalizationWebDeploy

For additional information, please refer to vendors site.

REFERENCES
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-anyconnect-ipc-KfQO9QhK