xdm Xsession symlink

xdm-xsession-symlink (29427) The risk level is classified as MediumMedium Risk

Description:

X Display Manager (xdm) could allow a local attacker to launch a symlink attack. The /tmp/xses-$USER files are created insecurely. A local attacker could exploit this vulnerability to create or overwrite arbitrary files on the system or view another user's Xsession error logs to obtain sensitive information.

Platforms Affected:

  • NetBSD, NetBSD 3.0
  • Sun, Solaris 10
  • Sun, Solaris 8
  • Sun, Solaris 9
  • X.Org, X.Org Server
  • XFree86, xdm

Remedy:

For NetBSD:
Upgrade to the latest version of Xsession, available from the NetBSD CVS Repository. See References.

For X.Org X Server:
Upgrade to the latest version of X.Org Xsession (dated 20060225 or later), or apply the appropriate patch for your system, available from the X.Org Foundation Web site. See References.

For Sun Solaris:
Refer to Sun Alert ID: 102652 for patch, upgrade, or suggested workaround information. See References.

For other distributions:
Contact your vendor for upgrade or patch information.

Consequences:

File Manipulation

References:

  • NetBSD CVS Repository, NetBSD CVS Repository at http://cvsweb.netbsd.org/bsdweb.cgi/.
  • Sun Alert ID: 102652, Security Vulnerability in X Display Manager (xdm(1)) Xsession Script at http://sunsolve.sun.com/search/document.do?assetkey=1-26-102652-1.
  • X.Org Foundation Web site, X.Org Foundation at http://www.x.org/.
  • ASA-2006-250: Sun Alert Notifications from Sun Weekly Report dated October 07 2006
  • CVE-2006-5215: The Xsession script, as used by X Display Manager (xdm) in NetBSD before 20060212, X.Org before 20060317, and Solaris 8 through 10 before 20061006, allows local users to overwrite arbitrary files, or read another user's Xsession errors file, via a symlink attack on a /tmp/xses-$USER file.
  • SA22992: Avaya CMS Sun Solaris X Display Manager Security Issue
  • SECTRACK ID: 1017015: Xdm May Let Local Users View the Error Log Files of a Target User

Reported:

Oct 06, 2006

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