Linux-PAM: Authentication bypass

Background

Linux-PAM (Pluggable Authentication Modules) is an architecture allowing the separation of the development of privilege granting software from the development of secure and appropriate authentication schemes.

Description

A flaw was found in Linux-Pam in the way it handle empty passwords for non-existing users.

Impact

A remote attacker, who only needs to know a non-existing username, could bypass security restrictions and authenticate as root user.

Workaround

Ensure that root account is protected by a non-empty password.

Resolution

All Linux-PAM users should upgrade to the latest version:

 # emerge --sync
 # emerge --ask --oneshot --verbose ">=sys-libs/pam-1.5.1"