rssh: Privilege escalation

Background

rssh is a restricted shell, allowing only a few commands like scp or sftp. It is often used as a complement to OpenSSH to provide limited access to users.

Description

Max Vozeler discovered that the rssh_chroot_helper command allows local users to chroot into arbitrary directories.

Impact

A local attacker could exploit this vulnerability to gain root privileges by chrooting into arbitrary directories.

Workaround

There is no known workaround at this time.

Resolution

All rssh users should upgrade to the latest version:

 # emerge --sync
 # emerge --ask --oneshot --verbose ">=app-shells/rssh-2.3.0"