CVE-2014-3636 in D-Bus
Summary
by MITRE
D-Bus 1.3.0 through 1.6.x before 1.6.24 and 1.8.x before 1.8.8 allows local users to (1) cause a denial of service (prevention of new connections and connection drop) by queuing the maximum number of file descriptors or (2) cause a denial of service (disconnect) via multiple messages that combine to have more than the allowed number of file descriptors for a single sendmsg call.
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Analysis
by VulDB Data Team • 04/03/2022
The vulnerability identified as CVE-2014-3636 affects the D-Bus messaging system, a critical component in many Linux-based operating systems that facilitates communication between applications and system services. This issue exists in D-Bus versions 1.3.0 through 1.6.x before 1.6.24 and 1.8.x before 1.8.8, representing a significant security flaw that can be exploited by local attackers to disrupt system operations. The vulnerability stems from improper handling of file descriptor limits within the D-Bus daemon, creating opportunities for malicious actors to exploit the system's resource management mechanisms. D-Bus serves as the primary inter-process communication framework in many desktop and server environments, making this vulnerability particularly concerning from a system stability perspective.
The technical flaw manifests in two distinct attack vectors that both result in denial of service conditions. The first vector involves queuing the maximum number of file descriptors, which can overwhelm the system's connection handling capabilities and prevent new connections from being established. This occurs because the D-Bus daemon does not properly validate or limit the number of file descriptors that can be queued during message processing. The second vector involves sending multiple messages that collectively exceed the allowed number of file descriptors for a single sendmsg system call, effectively causing connection drops and disrupting service availability. Both attack methods exploit the underlying assumption that the system can handle reasonable numbers of file descriptors without proper bounds checking, creating a scenario where malicious input can trigger resource exhaustion.
The operational impact of CVE-2014-3636 extends beyond simple service disruption to potentially compromise the entire system stability and availability. When local users can cause denial of service conditions in the D-Bus daemon, they effectively gain the ability to disrupt critical system services that depend on this messaging infrastructure. This vulnerability can affect desktop environments where D-Bus handles user session management, system notifications, and application communication, as well as server environments where D-Bus facilitates system administration tasks and service coordination. The attack vectors are particularly dangerous because they can be executed by any local user, making them accessible through common user accounts without requiring elevated privileges. From an attack perspective, this vulnerability aligns with techniques described in the MITRE ATT&CK framework under process injection and privilege escalation tactics, as it can be used to disrupt system operations and potentially create conditions for more sophisticated attacks.
The vulnerability has been classified as a buffer overflow condition in the context of file descriptor handling, corresponding to CWE-129, which deals with insufficient bounds checking on memory accesses. This weakness in the D-Bus implementation creates a situation where legitimate system operations can be disrupted through malformed input, demonstrating the importance of proper resource management in system-level components. Security professionals should note that this vulnerability represents a classic example of how improper input validation can lead to resource exhaustion attacks, a common pattern in operating system security. The fix implemented in versions 1.6.24 and 1.8.8 involved adding proper bounds checking and validation of file descriptor counts during message processing, ensuring that the system can handle legitimate operations while preventing malicious exploitation. Organizations should prioritize patching affected systems, as this vulnerability can be leveraged to create persistent availability issues that may be difficult to detect and remediate. The impact extends to compliance requirements for systems that must maintain high availability, as this vulnerability could potentially violate service level agreements and security standards such as those outlined in the NIST Cybersecurity Framework.