Certain Red Hat Enterprise Linux (RHEL) 4 and 5 packages for OpenSSH, as signed in August 2008 using a legitimate Red Hat GPG key, contain an externally introduced modification (Trojan Horse) that allows the package authors to have an unknown impact. NOTE: since the malicious packages were not distributed from any official Red Hat sources, the scope of this issue is restricted to users who may have obtained these packages through unofficial distribution points. As of 20080827, no unofficial distributions of this software are known.

This alert is primarily for those who may obtain Red Hat binary
packages via channels other than those of official Red Hat subscribers. Packages obtained by Red Hat Enterprise Linux subscribers via Red Hat Network are not at risk.

Redhat has provided a shell script which lists the affected packages and can verify that none of them are installed on a system at the following location:

https://www.redhat.com/security/data/openssh-blacklist-1.0.sh