CVE-2014-7300 in Gnome-shell
Summary
by MITRE
GNOME Shell 3.14.x before 3.14.1, when the Screen Lock feature is used, does not limit the aggregate memory consumption of all active PrtSc requests, which allows physically proximate attackers to execute arbitrary commands on an unattended workstation by making many PrtSc requests and leveraging a temporary lock outage, and the resulting temporary shell availability, caused by the Linux kernel OOM killer.
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Analysis
by VulDB Data Team • 12/12/2024
The vulnerability described in CVE-2014-7300 represents a critical memory exhaustion issue within the GNOME Shell 3.14.x series that specifically impacts the screen lock functionality. This flaw exists in versions prior to 3.14.1 and demonstrates how seemingly benign desktop features can be exploited to create significant security risks. The vulnerability is particularly concerning because it can be exploited by attackers who are physically present near the target workstation, making it a local privilege escalation vector that leverages the system's temporary lock mechanism.
The technical root cause of this vulnerability lies in the improper handling of Print Screen (PrtSc) requests within the GNOME Shell environment. When the screen lock feature is active, the system should enforce strict memory limits on all active requests to prevent resource exhaustion. However, the implementation fails to establish adequate memory consumption boundaries for PrtSc operations, allowing malicious actors to submit numerous simultaneous requests. This design flaw creates a memory leak scenario where each PrtSc request consumes system resources without proper throttling or resource management.
The operational impact of this vulnerability is particularly severe as it enables attackers to gain unauthorized command execution capabilities on unattended workstations. The exploitation process involves making multiple PrtSc requests in rapid succession, which eventually causes the Linux kernel's Out-of-Memory (OOM) killer to terminate processes to free up system resources. This termination creates a temporary window where the shell becomes temporarily available and responsive, providing the attacker with an opportunity to execute arbitrary commands on the compromised system. The vulnerability specifically targets the window between when the OOM killer terminates processes and when the system recovers, allowing for command execution during this brief temporary lock outage.
This vulnerability aligns with several cybersecurity frameworks and threat modeling approaches, including CWE-400 which categorizes it as an "Uncontrolled Resource Consumption" or "Resource Exhaustion" flaw. The attack vector described in the CVE corresponds to the ATT&CK technique T1059.001 for Command and Scripting Interpreter, specifically the use of shell commands. The physical proximity requirement places this vulnerability in the context of local attacks, similar to techniques described in ATT&CK's T1056.001 for Input Capture, where attackers exploit local system access to gain elevated privileges. The vulnerability also demonstrates characteristics of privilege escalation through resource exhaustion, which is categorized under ATT&CK's T1068 for Exploitation for Privilege Escalation.
Mitigation strategies for this vulnerability should focus on implementing proper resource management within the GNOME Shell environment. The most effective solution involves upgrading to GNOME Shell version 3.14.1 or later, where memory limits have been properly implemented for active PrtSc requests. System administrators should also consider implementing additional monitoring for unusual memory consumption patterns and establishing process limits for desktop applications. Network segmentation and proper access controls can help reduce the attack surface, while regular security updates ensure that such vulnerabilities are promptly addressed. The fix implemented in the patched version demonstrates proper resource management techniques that should be applied to similar desktop environments to prevent similar issues from occurring in the future.