CVE-2003-0794 in GDM
Summary
by MITRE
GDM 2.4.4.x before 2.4.4.4, and 2.4.1.x before 2.4.1.7, does not limit the number or duration of commands and uses a blocking socket connection, which allows attackers to cause a denial of service (resource exhaustion) by sending commands and not reading the results.
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Analysis
by VulDB Data Team • 06/07/2019
The vulnerability described in CVE-2003-0794 affects the GNOME Display Manager GDM version 2.4.4.x before 2.4.4.4 and 2.4.1.x before 2.4.1.7, representing a significant security weakness in the authentication and session management framework of the GNOME desktop environment. This issue manifests through improper resource management within the display manager's communication protocols, creating an avenue for malicious actors to exploit the system's operational integrity. The vulnerability specifically targets the command handling mechanism of GDM, which serves as the primary interface for user authentication and session initiation within GNOME-based systems.
The technical flaw resides in GDM's handling of socket connections and command processing, where the system fails to implement adequate limits on the number of commands that can be processed or the duration for which commands can remain active. This design oversight results in the use of blocking socket connections that do not timeout or enforce command quotas, allowing attackers to maintain open connections while continuously sending commands to the display manager. The blocking nature of these connections prevents the system from processing subsequent legitimate requests, effectively creating a resource exhaustion condition that can be leveraged to disrupt normal system operations. This behavior aligns with CWE-400, which addresses "Uncontrolled Resource Consumption" in software systems, and specifically relates to improper resource management patterns that fail to implement necessary rate limiting or connection timeout mechanisms.
The operational impact of this vulnerability extends beyond simple service disruption, as it enables attackers to consume system resources such as memory, file descriptors, and processing power in a sustained manner. When exploited, the vulnerability can lead to complete denial of service for legitimate users attempting to access the graphical desktop environment, effectively locking out authorized personnel while potentially causing system instability. The resource exhaustion occurs because each command sent to the display manager consumes system resources, and without proper limits, an attacker can maintain numerous connections simultaneously, preventing the system from servicing legitimate authentication requests. This type of attack pattern is consistent with the tactics described in the MITRE ATT&CK framework under the "Resource Exhaustion" technique, where adversaries consume system resources to deny service to legitimate users.
Mitigation strategies for this vulnerability require immediate implementation of patches and updates to the affected GDM versions, ensuring that system administrators deploy the corrected releases that include proper command limiting and timeout mechanisms. Organizations should also implement network-level controls such as firewall rules that limit connections to the display manager ports and implement monitoring systems to detect unusual connection patterns that may indicate exploitation attempts. Additionally, system administrators should configure appropriate resource limits and connection timeouts at the operating system level to prevent unbounded resource consumption. The vulnerability demonstrates the importance of implementing robust resource management practices in authentication systems and highlights the critical need for proper input validation and connection handling in display managers that serve as primary access points to graphical desktop environments.