iDefense Security Advisory 07.12.07: Red Hat Enterprise Linux init.d XFS Script chown Race Condition Vulnerability
Red Hat Enterprise Linux init.d XFS Script chown Race Condition
Vulnerability
iDefense Security Advisory 07.12.07
http://labs.idefense.com/intelligence/vulnerabilities/
Jul 12, 2007
I. BACKGROUND
XFS is the X Font Server, and is used to render fonts for the X Window
System. "init.d" refers to the startup and shutdown scripts used by
Linux distributions. These scripts are run by the init process to start
and stop various system services.
II. DESCRIPTION
Local exploitation of a race condition vulnerability in Red Hat Inc.'s
Enterprise Linux init.d XFS script allows an attacker to elevate their
privileges to root.
The XFS script is vulnerable to a race condition when it is started by
init, or by a system administrator. Specifically, it insecurely changes
the file permissions of a temporary file. This allows an attacker to
make any file on the system world writable.
III. ANALYSIS
Exploitation of this vulnerability results in an attacker gaining root
privileges on the affected system.
However, in order to exploit this, it is necessary for either the system
to be rebooted, or for the administrator to manually restart the XFS.
IV. DETECTION
iDefense has confirmed the existence of this vulnerability in Red Hat
Enterprise Linux version 4, and Fedora Core 6. Other versions may also
be affected.
V. WORKAROUND
iDefense is currently unaware of any workarounds for this issue.
VI. VENDOR RESPONSE
Red Hat has released errata updates for versions 4 and 5 of their
Enterprise Linux software. More information is available at the URLs
shown below.
https://rhn.redhat.com/errata/RHSA-2007-0519.html
https://rhn.redhat.com/errata/RHSA-2007-0520.html
VII. CVE INFORMATION
The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2007-3103 to this issue. This is a candidate for inclusion in
the CVE list (http://cve.mitre.org/), which standardizes names for
security problems.
VIII. DISCLOSURE TIMELINE
06/05/2007 Initial vendor notification
06/06/2007 Initial vendor response
07/12/2007 Coordinated public disclosure
IX. CREDIT
The discoverer of this vulnerability wishes to remain anonymous.
Get paid for vulnerability research
http://labs.idefense.com/methodology/vulnerability/vcp.php
Free tools, research and upcoming events
http://labs.idefense.com/
X. LEGAL NOTICES
Copyright © 2007 iDefense, Inc.
Permission is granted for the redistribution of this alert
electronically. It may not be edited in any way without the express
written consent of iDefense. If you wish to reprint the whole or any
part of this alert in any other medium other than electronically,
please e-mail customerservice@xxxxxxxxxxxx for permission.
Disclaimer: The information in the advisory is believed to be accurate
at the time of publishing based on currently available information. Use
of the information constitutes acceptance for use in an AS IS condition.
There are no warranties with regard to this information. Neither the
author nor the publisher accepts any liability for any direct,
indirect, or consequential loss or damage arising from use of, or
reliance on, this information.