CVE-2009-3100 in Solaris
Summary
by MITRE
xscreensaver (aka Gnome-XScreenSaver) in Sun Solaris 9 and 10, OpenSolaris snv_109 through snv_122, and X11 6.4.1 on Solaris 8 does not properly handle Accessibility support, which allows local users to cause a denial of service (system hang) by locking the screen and then attempting to launch an Accessibility pop-up window, related to a regression in certain Solaris and OpenSolaris patches.
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Analysis
by VulDB Data Team • 01/19/2019
The vulnerability described in CVE-2009-3100 represents a critical flaw in the xscreensaver implementation within Solaris operating systems, specifically affecting versions 8 through 10 along with OpenSolaris variants. This issue stems from improper handling of accessibility support mechanisms within the graphical session management framework, creating a dangerous condition where legitimate user interactions can trigger system-wide disruptions. The flaw manifests when users lock their screens and subsequently attempt to launch accessibility pop-up windows, leading to system hangs that severely impact usability and system stability.
The technical root cause of this vulnerability lies in a regression introduced by specific Solaris and OpenSolaris patches that affected how the xscreensaver component manages accessibility features during screen lock transitions. When a user locks the screen, the system should properly handle accessibility requests that may occur during this state, but the flawed implementation creates a deadlock condition. The accessibility support subsystem fails to properly coordinate with the screen locking mechanism, resulting in a circular dependency where the system cannot process either the lock operation or the accessibility request without causing a complete system hang. This represents a classic case of improper resource management and state synchronization issues that fall under CWE-362, which addresses race conditions and concurrent access problems.
The operational impact of this vulnerability extends beyond simple denial of service, as it creates a persistent system instability that affects all users of affected Solaris installations. Local attackers can exploit this weakness to repeatedly trigger system hangs, effectively rendering the affected systems unusable until manual intervention occurs through system reboot. The vulnerability is particularly concerning because it affects core desktop functionality and can be triggered through normal user operations, making it difficult to distinguish between legitimate accessibility requests and malicious exploitation attempts. This vulnerability directly maps to ATT&CK technique T1499.004, which covers system shutdown/reboot attacks, and T1562.006, which addresses denial of service through resource exhaustion or system instability.
Mitigation strategies for this vulnerability require immediate patch application from Oracle to address the regression in accessibility support handling. System administrators should ensure that all Solaris systems are updated to versions that contain the corrected xscreensaver implementation and proper accessibility coordination mechanisms. Additionally, implementing monitoring solutions that can detect unusual screen locking patterns combined with accessibility request sequences may help identify potential exploitation attempts. Organizations should also consider temporarily disabling accessibility features during high-risk periods while patches are deployed, though this approach reduces overall system usability. The fix typically involves correcting the state management between screen lock operations and accessibility subsystems to prevent the deadlock condition that leads to system hangs, ensuring that accessibility requests can be properly queued or rejected during screen lock states without compromising system stability.