GNOME screensaver 2.20 in Ubuntu 7.10, when used with Compiz, does not properly reserve input focus, which allows attackers with physical access to take control of the session after entering an Alt-Tab sequence, a related issue to CVE-2007-3069.

Most screen savers create a top-level fullscreen window to cover the desktop, and grab the input with that window. Compiz has an option to un-redirect that window, but in some cases, this breaks the grab and compromises the locked screen. (CVE-2007-3920)

This update fixes multiple vulnerabilities reported by iDefense :

  - CVE-2008-2360 - RENDER Extension heap buffer overflow

  - CVE-2008-2361 - RENDER Extension crash

  - CVE-2008-2362 - RENDER Extension memory corruption 

  - CVE-2008-1379 - MIT-SHM arbitrary memory read

  - CVE-2008-1377 - RECORD and Security extensions memory     corruption Additionally fixes for :

  - gnome-screensaver loses keyboard focus lock under compiz     (CVE-2007-3920)

This update fixes multiple vulnerabilities reported by iDefense :

  - CVE-2008-2360 - RENDER Extension heap buffer overflow

  - CVE-2008-2361 - RENDER Extension crash

  - CVE-2008-2362 - RENDER Extension memory corruption 

  - CVE-2008-1379 - MIT-SHM arbitrary memory read

  - CVE-2008-1377 - RECORD and Security extensions memory     corruption Additionally fixes for :

  - XvReputImage crashes due to Nulled PortPriv->pDraw

  - gnome-screensaver loses keyboard focus lock under compiz     (CVE-2007-3920)

Updated compiz packages that prevent Compiz from breaking screen saver grabs are now available for Red Hat Enterprise Linux 5.

This update has been rated as having low security impact by the Red Hat Security Response Team.

Compiz is an OpenGL-based window and compositing manager.

Most screen savers create a top-level fullscreen window to cover the desktop, and grab the input with that window. Compiz has an option to un-redirect that window, but in some cases, this breaks the grab and compromises the locked screen. (CVE-2007-3920)

Users of compiz are advised to upgrade to these updated packages, which remove this option to resolve this issue.

When enabling the 'unredirect fullscreen windows' option, compiz will unredirect fullscreen windows to improve performace. However, unredirecting will as a side effect break any grabs on that window, which compromises most screensavers. This X server update suppresses this unintended side effect and restores the security of the screensavers. See also CVE-2007-3069.

Note that Tenable Network Security has extracted the preceding description block directly from the Fedora security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

USN-537-1 fixed vulnerabilities in gnome-screensaver. The fixes were incomplete, and only reduced the scope of the vulnerability, without fully solving it. This update fixes related problems in compiz.

Jens Askengren discovered that gnome-screensaver became confused when running under Compiz, and could lose keyboard lock focus. A local attacker could exploit this to bypass the user's locked screen saver.

Note that Tenable Network Security has extracted the preceding description block directly from the Ubuntu security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

Jens Askengren discovered that gnome-screensaver became confused when running under Compiz, and could lose keyboard lock focus. A local attacker could exploit this to bypass the user's locked screen saver.

Note that Tenable Network Security has extracted the preceding description block directly from the Ubuntu security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

ID	Name	Product	Family	Severity
60403	Scientific Linux Security Update : compiz on SL5.x i386/x86_64	Nessus	Scientific Linux Local Security Checks	medium
33166	openSUSE 10 Security Update : xorg-x11-server (xorg-x11-server-5316)	Nessus	SuSE Local Security Checks	critical
33165	openSUSE 10 Security Update : xorg-x11-Xvnc (xorg-x11-Xvnc-5317)	Nessus	SuSE Local Security Checks	critical
32427	RHEL 5 : compiz (RHSA-2008:0485)	Nessus	Red Hat Local Security Checks	medium
30083	Fedora 7 : xorg-x11-server-1.3.0.0-16.fc7 (2008-0956)	Nessus	Fedora Local Security Checks	medium
30082	Fedora 8 : xorg-x11-server-1.3.0.0-40.fc8 (2008-0930)	Nessus	Fedora Local Security Checks	medium
28144	Ubuntu 7.10 : compiz vulnerability (USN-537-2)	Nessus	Ubuntu Local Security Checks	medium
28143	Ubuntu 7.10 : gnome-screensaver vulnerability (USN-537-1)	Nessus	Ubuntu Local Security Checks	medium

Detections

Analytics

CVE-2007-3920

critical

Tenable Plugins

medium

critical

critical

medium

medium

medium

medium

medium