Software Engineering Institute

CWE-121: Stack-based Buffer Overflow

Watchguard Extensible Threat Management (XTM) version 11.7.4 and possibly earlier versions contain a buffer overflow vulnerability when reading large cookie requests. Remote administration is enabled by default on TCP/8080 for the virtual appliances (XTMv). The physical XTM appliances do not have this feature enabled by default.

WGagent is one of the processes running on the XTM appliance, which is responsible for parsing web cookies sent to the appliance’s web management interface. By creating a maliciously crafted cookie that contains an arbitrarily large sessionid value and connecting to the XTM appliance’s web management interface, an unauthenticated attacker can exploit this vulnerability to execute code on the appliance.

The WGagent process runs with low privileges and from a chroot jail, but it does have enough privilege to access the configuration file and change passwords.

A remote unauthenticated attacker may be able to cause a denial of service, or execute arbitrary code on the appliance.

Apply an Update

Users are advised to apply the Watchguard XTM version 11.8 patch. If applying the patch is not possible, please consider the following workaround.

Restrict access to the Watchguard XTM interface

Restrict access to the Watchguard XTM web interface to trusted networks. If possible, configure management and transit networks for separate VLANs, or restrict access to the device using IP access lists.