CVE-2014-7824 in D-Bus
Summary
by MITRE
D-Bus 1.3.0 through 1.6.x before 1.6.26, 1.8.x before 1.8.10, and 1.9.x before 1.9.2 allows local users to cause a denial of service (prevention of new connections and connection drop) by queuing the maximum number of file descriptors. NOTE: this vulnerability exists because of an incomplete fix for CVE-2014-3636.1.
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Analysis
by VulDB Data Team • 04/04/2022
The vulnerability described in CVE-2014-7824 represents a significant denial of service weakness in the D-Bus message bus system that affects multiple versions of the software. This issue specifically targets the handling of file descriptors within the D-Bus communication framework, creating a scenario where malicious local users can exploit the system's resource management capabilities to disrupt normal operations. The vulnerability is particularly concerning because it was introduced as a partial fix for CVE-2014-3636, demonstrating how remediation efforts can sometimes create new attack surfaces or fail to address all aspects of the underlying problem. The affected versions span across several major release lines including 1.3.0 through 1.6.x before 1.6.26, 1.8.x before 1.8.10, and 1.9.x before 1.9.2, indicating a widespread impact across the D-Bus ecosystem.
The technical flaw manifests in the improper handling of file descriptor limits within the D-Bus daemon implementation. When local users queue the maximum number of file descriptors, the system reaches its resource exhaustion threshold, causing the message bus to become unresponsive. This occurs because the D-Bus daemon maintains a limited pool of file descriptors for managing connections, and when this pool is exhausted through malicious queuing, the system cannot accept new connections or maintain existing ones. The vulnerability exploits the fact that the daemon does not properly enforce or manage the maximum number of file descriptors that can be queued, allowing an attacker to consume all available resources and effectively disable the service. This behavior falls under CWE-400, which specifically addresses the weakness of uncontrolled resource consumption, and represents a classic example of resource exhaustion attacks that can be leveraged to create denial of service conditions.
The operational impact of CVE-2014-7824 extends beyond simple service disruption, as D-Bus serves as a fundamental communication mechanism in many Linux systems and applications. The vulnerability can affect critical system components that rely on D-Bus for inter-process communication, potentially causing cascading failures throughout the system. When new connections are prevented and existing connections are dropped, it can impact desktop environments, system services, application launching mechanisms, and any software that depends on D-Bus for proper operation. The attack vector is particularly dangerous because it requires only local access, making it difficult to detect and prevent through network-based security measures. This local privilege escalation scenario aligns with ATT&CK technique T1068, which covers local privilege escalation through resource exhaustion attacks, and demonstrates how seemingly minor implementation flaws can create significant operational risks.
Mitigation strategies for CVE-2014-7824 should focus on both immediate patching and operational hardening measures. The primary solution involves updating to D-Bus versions 1.6.26, 1.8.10, or 1.9.2, which contain the proper fixes for this vulnerability. Organizations should also implement monitoring for unusual file descriptor usage patterns and establish resource limits for D-Bus daemon processes to prevent exploitation. System administrators should consider implementing process isolation and resource management policies that limit the number of file descriptors available to D-Bus processes, while also ensuring that proper logging and alerting mechanisms are in place to detect potential exploitation attempts. Additionally, regular vulnerability assessments should be conducted to identify similar issues in other system components that might be vulnerable to resource exhaustion attacks, particularly those that handle inter-process communication or network connections in similar ways to D-Bus. The vulnerability highlights the importance of thorough testing of security patches and the need for comprehensive vulnerability management programs that address both known issues and potential regression vulnerabilities.