SELinux PAM: Local password guessing attack

1. Gentoo Linux Security Advisory

Advisory Reference	GLSA 200510-22 / PAM
Release Date	October 28, 2005
Latest Revision	October 28, 2005: 01
Impact	normal
Exploitable	local

Package	Vulnerable versions	Unaffected versions	Architecture(s)
sys-libs/pam	< 0.78-r3	>= 0.78-r3	All supported architectures

Related bugreports: #109485

Synopsis

A vulnerability in the SELinux version of PAM allows a local attacker to brute-force system passwords.

2. Impact Information

Background

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. SELinux is an operating system based on Linux which includes Mandatory Access Control.

Description

The SELinux patches for PAM introduce a vulnerability allowing a password to be checked with the unix_chkpwd utility without delay or logging. This vulnerability doesn't affect users who do not run SELinux.

Impact

A local attacker could exploit this vulnerability to brute-force passwords and escalate privileges on an SELinux system.

3. Resolution Information

Workaround

There is no known workaround at this time.

Resolution

All SELinux PAM users should upgrade to the latest version:

Code Listing 3.1: Resolution

# emerge --sync
# emerge --ask --oneshot --verbose ">=sys-libs/pam-0.78-r3"

4. References

CVE-2005-2977

Updated October 28, 2005

Summary: This is a Gentoo Linux Security Advisory

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