Technical Description

Multiple vulnerabilities have been idenitified in X.Org X11 Server, which could be exploited by malicious authorized clients to disclose sensitive information, cause a denial of service or execute arbitrary code.

The first issue is caused by an invalid array index within the XFree86-Misc extension when processing "PassMessage" requests, which could be exploited by attackers to crash a vulnerable server or execute arbitrary code with "root" privileges.

The second vulnerability is caused by integer overflow errors in the EVI extension when processing "GetVisualInfo" requests, which could be exploited by attackers to crash a vulnerable server or execute arbitrary code with "root" privileges.

The third issue is caused by integer overflow errors in the MIT-SHM extension when allocating the pixmap, which could be exploited by attackers to crash a vulnerable server or execute arbitrary code with "root" privileges.

The fourth vulnerability is caused by a memory corruption error in the "ProcGetReservedColormapEntries()" function within the TOG-CUP extension, which could be exploited by attackers to read arbitrary memory data.

The fifth issue is caused by a memory corruption error in the Xinput extension when processing malformed requests, which could be exploited by attackers to crash a vulnerable server or execute arbitrary code with "root" privileges.

The sixth vulnerability is caused by a buffer overflow error when parsing PCF fonts, which could be exploited by malicious users to crash a vulnerable server or execute arbitrary code with "root" privileges.

The seventh issue is caused by a design error in the "X :1 -sp <file>" command when displaying error messages, which could be exploited by a malicious user to verify the existence of files and directories in restricted directories.

Affected Products

X.org X11 version R7.3 and prior
Xorg xserver versions prior to 1.4.1

Solution

Apply patch for Xorg xserver version 1.2 :
ftp://ftp.freedesktop.org/pub/xorg/X11R7.2/patches/xorg-xserver-1.2-multiple-overflows.diff

Apply patch for Xorg xserver version 1.4 :
ftp://ftp.freedesktop.org/pub/xorg/X11R7.3/patches/xorg-xserver-1.4-multiple-overflows.diff

Apply patch for libXfont :
ftp://ftp.freedesktop.org/pub/xorg/X11R7.3/patches/xorg-libXfont-1.3.1-pcf-parser.diff

References

http://www.vupen.com/english/advisories/2008/0179
http://lists.freedesktop.org/archives/xorg/2008-January/031918.html
http://labs.idefense.com/intelligence/vulnerabilities/display.php?id=646
http://labs.idefense.com/intelligence/vulnerabilities/display.php?id=645
http://labs.idefense.com/intelligence/vulnerabilities/display.php?id=644
http://labs.idefense.com/intelligence/vulnerabilities/display.php?id=643

Credits

Vulnerabilities reported by regenrecht, VeriSign iDefense Labs, Takuya Shiozaki and CERT/CC.

ChangeLog

2008-01-18 : Initial release

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