CVE-2007-6389 in screensaver
Summary
by MITRE
The notify feature in GNOME screensaver (gnome-screensaver) 2.20.0 might allow local users to read the clipboard contents and X selection data for a locked session by using ctrl-V.
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Analysis
by VulDB Data Team • 08/08/2019
The vulnerability described in CVE-2007-6389 represents a significant security flaw in the GNOME screensaver implementation that undermines the fundamental security assumptions of desktop session locking mechanisms. This issue affects GNOME screensaver version 2.20.0 and specifically targets the notify feature that is designed to provide visual feedback when users interact with the locked session. The vulnerability exploits a critical design oversight that allows local attackers to bypass the intended security boundaries of the locked desktop environment, potentially exposing sensitive information that should remain protected during session lock states.
The technical flaw manifests through the improper handling of clipboard and X selection data within the locked session context. When a GNOME session is locked, the screensaver should isolate the user interface from potential data leakage through various mechanisms including clipboard access controls. However, the vulnerability enables attackers to utilize standard keyboard shortcuts such as ctrl-V to access clipboard contents and X selection data that were previously available to the user before locking. This occurs because the notify feature fails to properly enforce access controls that would normally prevent such operations during session lock states, creating an unintended information disclosure channel that violates basic security principles.
The operational impact of this vulnerability extends beyond simple information disclosure to represent a serious threat to user privacy and data security in desktop environments. Local attackers can exploit this weakness to access sensitive data such as passwords, personal messages, confidential documents, and other clipboard contents that users may have copied while working in the unlocked session. The vulnerability is particularly concerning because it operates entirely within the local user context without requiring elevated privileges or network access, making it easily exploitable in environments where users rely on session locking for security. This type of vulnerability directly contravenes the principle of least privilege and undermines the trust users place in desktop session locking mechanisms.
Security professionals should consider this vulnerability in the context of broader desktop security frameworks and attack surface management strategies. The flaw aligns with CWE-200, which addresses improper output neutralization for logs, and relates to ATT&CK technique T1555.001 for credentials from password storage components, though specifically targeting clipboard data rather than traditional credential stores. Organizations should implement immediate mitigations including updating to patched versions of GNOME screensaver, reviewing system configurations to disable unnecessary notify features, and educating users about the importance of proper session management. Additionally, security monitoring should include detection of unauthorized clipboard access patterns during session lock states, and system administrators should consider implementing additional access controls and session management policies to prevent similar vulnerabilities from occurring in other desktop components.
This vulnerability demonstrates the critical importance of thorough security testing of desktop session management features and highlights how seemingly minor implementation details can create significant security risks. The issue emphasizes the need for comprehensive security reviews of all user interface components that interact with system resources during session state transitions, particularly in environments where multiple users share systems or where sensitive data processing occurs. Proper security architecture for desktop environments requires that session lock states provide complete isolation from potential data leakage channels, including clipboard, selection, and notification mechanisms that could inadvertently expose sensitive information to unauthorized local access.