A vulnerability in GNU Bash when processing trailing strings after function definitions in the values of environment variables allows remote attackers to execute arbitrary code via a crafted environment. This vulnerability can be leveraged to bypass restricted SSH access (i.e. when the SSH server forces the execution of a specific command, ignoring any command supplied by the client, either by specifying a 'ForceCommand' directive in the 'sshd_config' file, or by using the 'command' keyword in the 'authorized_keys' file) when the default shell for the user is Bash, allowing the remote attacker to execute arbitrary commands on the vulnerable system. The module included leverages this vulnerability to install an agent.
Wednesday, October 8, 2014 - 00:00