XScreenSaver getpwuid() function authentication bypass

xscreensaver-getpwuid-authentication-bypass (34054) The risk level is classified as MediumMedium Risk

Description:

XScreenSaver could allow a local attacker to bypass authentication, caused by the improper parsing of a call to the getpwuid() function. If the application is using a remote directory service for login during a network outage, a local attacker could exploit this vulnerability to crash the application to unlock the screen and gain unauthorized access to the victim's system.

*CVSS:

Base Score: 4.9
  Access Vector: Local
  Access Complexity: Low
  Authentication: Not Required
  Confidentiality Impact: Partial
  Integrity Impact: Partial
  Availability Impact: Partial
 
Temporal Score: 3.6
  Exploitability: Unproven
  Remediation Level: Official-Fix
  Report Confidence: Confirmed

Consequences:

Bypass Security

Remedy:

Upgrade to the latest version of XScreenSaver (5.02 or later), available from the XScreenSaver Web site. See References.

For Red Hat Linux (xscreensaver):
Refer to RHSA-2007:0322-4 for patch, upgrade, or suggested workaround information. See References.

For Gentoo Linux (XScreenSaver):
Refer to GLSA 200705-14 for patch, upgrade, or suggested workaround information. See References.

For Ubuntu Linux (xscreensaver):
Refer to USN-474-1 for patch, upgrade, or suggested workaround information. See References.

For Mandriva Linux (xscreensaver):
Refer to MDKSA-2007:097 for patch, upgrade, or suggested workaround information. See References.

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

References:

  • Red Hat Bugzilla Bug 237003: CVE-2007-1859 xscreensaver authentication bypass.
  • XScreenSaver Web site: XScreenSaver.
  • ASA-2007-264: XScreenSaver security update (RHSA-2007-0322)
  • BID-23783: Xscreensaver Local Denial Of Service Vulnerability
  • CVE-2007-1859: XScreenSaver 4.10, when using a remote directory service for credentials, does not properly handle the results from the getpwuid function in drivers/lock.c when there is no network connectivity, which causes XScreenSaver to crash and unlock the screen and allows local users to bypass authentication.
  • GLSA-200705-14: XScreenSaver: Privilege escalation
  • MDKSA-2007:097: Updated xscreensaver packages fix vulnerability
  • OSVDB ID: 35531: XScreenSaver getpwuid() Failed Network Authentication Screen Lock Bypass
  • RHSA-2007-0322: Important: xscreensaver security update
  • SA25065: XScreenSaver "getpwuid()" Authentication Bypass Weakness
  • SECTRACK ID: 1017996: XScreenSaver LDAP Authentication Error Lets Physically Local Users Bypass the Password Feature
  • USN-474-1: xscreensaver vulnerability

Platforms Affected:

  • Canonical Ubuntu 6.06 LTS
  • Canonical Ubuntu 6.10
  • Canonical Ubuntu 7.04
  • Gentoo Linux
  • JWZ XScreenSaver 4.10
  • MandrakeSoft Mandrake Linux 2007 X86_64
  • MandrakeSoft Mandrake Linux 2007
  • MandrakeSoft Mandrake Linux 2007.1 X86_64
  • MandrakeSoft Mandrake Linux 2007.1
  • MandrakeSoft Mandrake Linux 2008.0 X86_64
  • MandrakeSoft Mandrake Linux Corporate Server 3.0 X86_64
  • MandrakeSoft Mandrake Linux Corporate Server 3.0
  • RedHat Enterprise Linux 2.1 WS
  • RedHat Enterprise Linux 2.1 AS
  • RedHat Enterprise Linux 2.1 ES
  • RedHat Enterprise Linux 3 WS
  • RedHat Enterprise Linux 3 AS
  • RedHat Enterprise Linux 3 Desktop
  • RedHat Enterprise Linux 3 ES
  • RedHat Enterprise Linux 4 ES
  • RedHat Enterprise Linux 4 Desktop
  • RedHat Enterprise Linux 4 AS
  • RedHat Enterprise Linux 4 WS
  • RedHat Enterprise Linux 4.5.z ES
  • RedHat Enterprise Linux 4.5.z AS
  • RedHat Linux Advanced Workstation 2.1 Itanium

Reported:

May 02, 2007

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