bsd-mailx could be made to run programs if it parsed a specially crafted email address.
It was discovered that bsd-mailx contained a feature that allowed syntactically valid email addresses to be treated as shell commands. A remote attacker could possibly use this issue with a valid email address to execute arbitrary commands.
7 January 2015
A security issue affects these releases of Ubuntu and its derivatives:
bsd-mailx could be made to run programs if it parsed a specially crafted email address.
It was discovered that bsd-mailx contained a feature that allowed syntactically valid email addresses to be treated as shell commands. A remote attacker could possibly use this issue with a valid email address to execute arbitrary commands.
This functionality has now been disabled by default, and can be re-enabled with the “expandaddr” configuration option. This update alone does not remove all possibilities of command execution. In environments where scripts use mailx to process arbitrary email addresses, it is recommended to modify them to use a “–” separator before the address to properly handle those that begin with “-”. In addition, specifying sendmail options after the “–” separator is no longer supported, existing scripts may need to be modified to use the “-a” option instead.
The problem can be corrected by updating your system to the following package versions:
To update your system, please follow these instructions: https://wiki.ubuntu.com/Security/Upgrades.
In general, a standard system update will make all the necessary changes.
Vulmon