rssh: Format string vulnerability

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

Florian Schilhabel from the Gentoo Linux Security Audit Team found a format string vulnerability in rssh syslogging of failed commands.

Impact

Using a malicious command, it may be possible for a remote authenticated user to execute arbitrary code on the target machine with user rights, effectively bypassing any restriction of rssh.

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-2.2.2"