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SELinux PAM: Local password guessing attack


1.  Gentoo Linux Security Advisory

Version Information

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


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

2.  Impact Information


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.


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.


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

3.  Resolution Information


There is no known workaround at this time.


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


Page updated October 28, 2005

Summary: This is a Gentoo Linux Security Advisory

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