CVE-2014-9374 in Asterisk
Summary
by MITRE
Double free vulnerability in the WebSocket Server (res_http_websocket module) in Asterisk Open Source 11.x before 11.14.2, 12.x before 12.7.2, and 13.x before 13.0.2 and Certified Asterisk 11.6 before 11.6-cert9 allows remote attackers to cause a denial of service (crash) by sending a zero length frame after a non-zero length frame.
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Analysis
by VulDB Data Team • 03/01/2022
The CVE-2014-9374 vulnerability represents a critical double free memory corruption issue within the WebSocket server implementation of Asterisk Open Source and Certified Asterisk versions. This vulnerability exists in the res_http_websocket module, which handles WebSocket connections for the Asterisk telephony platform. The flaw manifests when the system processes a sequence of WebSocket frames where a zero-length frame is sent immediately following a non-zero length frame. This specific pattern triggers a memory management error that can be exploited by remote attackers to cause system instability.
The technical root cause of this vulnerability stems from improper memory deallocation handling within the WebSocket frame processing logic. When the WebSocket server receives a non-zero length frame followed by a zero-length frame, the memory management routines fail to properly track the allocated memory blocks, resulting in a double free condition. This occurs because the system attempts to free the same memory location twice, which corrupts the heap structure and can lead to arbitrary code execution or complete system crash. The vulnerability is classified as a CWE-415: Double Free, which is a well-known memory safety issue that has been documented in numerous security advisories across various software platforms. The flaw specifically impacts the memory management subsystem of Asterisk's HTTP WebSocket implementation, making it particularly dangerous for telephony infrastructure deployments.
The operational impact of CVE-2014-9374 extends beyond simple denial of service to potentially enable more sophisticated attacks. Remote attackers can leverage this vulnerability to crash the Asterisk server, disrupting voice communication services and potentially causing service outages that affect businesses and organizations relying on telephony infrastructure. The attack vector requires only sending specially crafted WebSocket frames to the affected server, making it particularly dangerous as it can be executed without authentication or privileged access. This vulnerability affects multiple versions of Asterisk including 11.x before 11.14.2, 12.x before 12.7.2, and 13.x before 13.0.2, indicating a widespread impact across the Asterisk platform. The potential for exploitation aligns with ATT&CK technique T1499.004: Endpoint Denial of Service, which targets system resources to prevent normal operations.
Mitigation strategies for this vulnerability require immediate patching of affected Asterisk installations to the patched versions mentioned in the CVE description. Organizations should also implement network-level protections such as firewall rules that restrict WebSocket traffic to trusted sources and monitor for unusual WebSocket frame patterns. Additionally, system administrators should consider implementing intrusion detection systems that can identify and alert on suspicious WebSocket traffic patterns that match the vulnerability characteristics. The remediation process should include thorough testing of patched systems to ensure that the vulnerability is fully resolved without introducing new issues. Organizations using Asterisk in production environments should also review their WebSocket configuration and consider disabling WebSocket functionality if it is not essential for their operations, as this provides an additional layer of defense against this and similar vulnerabilities.