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.
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.
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.
iDefense has confirmed the existence of this vulnerability in RedHat Enterprise Linux version 4, and Fedora Core 6. Other versions may also be affected.
iDefense is currently unaware of any workarounds for this issue.
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.
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.
06/05/2007 Initial vendor notification
06/06/2007 Initial vendor response
07/12/2007 Coordinated public disclosure
The discoverer of this vulnerability wishes to remain anonymous.
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