Vulnerability Note VU#938323

Postfix local privilege escalation

Original Release date: 18 Aug 2008 | Last revised: 19 Aug 2008

Overview

The Postfix MTA contains a local privilege escalation vulnerability.

Description

Postfix is an mail transport agent (MTA) that is used by several Unix-like operating systems. Symbolic links and hard links are types of files that reference other files. Unlike hard links, symbolic links can point to directories and use relative pathnames.

On some non-POSIX.1-2001 and X/Open XPG4v2 compliant systems, users can hardlink symlinks which are owned by the root user. Postfix allows root-owned symlinks to be used as a mail destination folder. A hard link to a Postfix root-owned symlink could point to a file that can be overwritten by Postfix, regardless of the permissions of the destination file.

Impact

A local, authenticated attacker may be able to overwrite arbitrary files, possibly gaining elevated privileges.

Solution

Upgrade
See http://article.gmane.org/gmane.mail.postfix.announce/110 for information about obtaining updated software. Users who do not compile Postfix from source should see the systems affected section below for a partial list of affected vendors.


Set mailbox permissions

Making the system mail spool directory root-owned may mitigate this vulnerability. See http://article.gmane.org/gmane.mail.postfix.announce/110 for specific information about this and other workarounds.

Systems Affected (Learn More)

VendorStatusDate NotifiedDate Updated
Gentoo LinuxAffected01 Aug 200818 Aug 2008
Mandriva, Inc.Affected01 Aug 200818 Aug 2008
SUSE LinuxAffected01 Aug 200818 Aug 2008
UbuntuAffected01 Aug 200819 Aug 2008
DragonFly BSD ProjectNot Affected01 Aug 200802 Aug 2008
Sun Microsystems, Inc.Not Affected01 Aug 200819 Aug 2008
Apple Computer, Inc.Unknown01 Aug 200819 Aug 2008
Conectiva Inc.Unknown01 Aug 200801 Aug 2008
Cray Inc.Unknown01 Aug 200801 Aug 2008
Debian GNU/LinuxUnknown01 Aug 200801 Aug 2008
EMC CorporationUnknown01 Aug 200801 Aug 2008
Engarde Secure LinuxUnknown01 Aug 200801 Aug 2008
F5 Networks, Inc.Unknown01 Aug 200801 Aug 2008
Fedora ProjectUnknown01 Aug 200801 Aug 2008
FreeBSD, Inc.Unknown01 Aug 200801 Aug 2008
If you are a vendor and your product is affected, let us know.View More »

CVSS Metrics (Learn More)

Group Score Vector
Base N/A N/A
Temporal N/A N/A
Environmental N/A N/A

References

Credit

Thanks to Wietse Venema for information that was used in this report. Sebastian Krahmer of SuSE is credited for discovering and reporting this issue.

This document was written by Ryan Giobbi.

Other Information

  • CVE IDs: CVE-2008-2936
  • Date Public: 18 Aug 2008
  • Date First Published: 18 Aug 2008
  • Date Last Updated: 19 Aug 2008
  • Severity Metric: 4.20
  • Document Revision: 20

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