Linux-PAM: Privilege escalation

1. Gentoo Linux Security Advisory

Advisory Reference	GLSA 200909-01 / pam
Release Date	September 07, 2009
Latest Revision	September 07, 2009: 01
Impact	normal
Exploitable	remote

Package	Vulnerable versions	Unaffected versions	Architecture(s)
sys-libs/pam	< 1.0.4	>= 1.0.4	All supported architectures

Related bugreports: #261512

Synopsis

An error in the handling of user names of Linux-PAM might allow remote attackers to cause a Denial of Service or escalate privileges.

2. Impact Information

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

Marcus Granado repoted that Linux-PAM does not properly handle user names that contain Unicode characters. This is related to integer signedness errors in the pam_StrTok() function in libpam/pam_misc.c.

Impact

A remote attacker could exploit this vulnerability to cause a Denial of Service. A remote authenticated attacker could exploit this vulnerability to log in to a system with the account of a user that has a similar user name, but with non-ASCII characters.

3. Resolution Information

Workaround

There is no known workaround at this time.

Resolution

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

Code Listing 3.1: Resolution

# emerge --sync
# emerge --ask --oneshot --verbose ">=sys-libs/pam-1.0.4"

4. References

CVE-2009-0887

Page updated September 07, 2009

Summary: This is a Gentoo Linux Security Advisory

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