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 platforms. At boot and shutdown time, these scripts are run by
the init program 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 RedHat
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.
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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 customer service 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.
