CVE-2012-5977 in Asterisk
Summary
by MITRE
Asterisk Open Source 1.8.x before 1.8.19.1, 10.x before 10.11.1, and 11.x before 11.1.2; Certified Asterisk 1.8.11 before 1.8.11-cert10; and Asterisk Digiumphones 10.x-digiumphones before 10.11.1-digiumphones, when anonymous calls are enabled, allow remote attackers to cause a denial of service (resource consumption) by making anonymous calls from multiple sources and consequently adding many entries to the device state cache.
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Analysis
by VulDB Data Team • 04/20/2021
The vulnerability identified as CVE-2012-5977 represents a significant denial of service weakness in Asterisk Open Source and related telephony systems. This flaw specifically affects versions prior to the mentioned secure releases, creating a critical operational risk for organizations relying on Asterisk for voice communication services. The vulnerability manifests when anonymous call handling is enabled, allowing malicious actors to exploit the system's resource management mechanisms through a carefully orchestrated series of calls from multiple sources.
The technical root cause of this vulnerability lies in the improper handling of device state cache management within the Asterisk telephony platform. When anonymous calls are processed, the system creates and maintains numerous entries in its device state cache without adequate rate limiting or resource allocation controls. This cache grows uncontrollably as attackers submit calls from different sources, leading to excessive memory consumption and eventual system resource exhaustion. The vulnerability operates at the application layer and can be classified under CWE-400, which specifically addresses uncontrolled resource consumption, making it a classic example of a resource exhaustion attack.
The operational impact of CVE-2012-5977 extends far beyond simple service disruption, as it can completely incapacitate telephony services within affected organizations. Attackers can maintain sustained denial of service conditions by simply making repeated anonymous calls from multiple sources, causing the system to consume all available memory resources allocated for device state caching. This creates a cascading effect that can impact not only the telephony infrastructure but also potentially affect related services that depend on the Asterisk platform. The vulnerability is particularly dangerous because it requires minimal technical expertise to exploit and can be executed from multiple locations simultaneously.
Organizations should implement immediate mitigations including disabling anonymous call handling when not required, implementing rate limiting mechanisms for incoming calls, and establishing proper monitoring for unusual device state cache growth patterns. The ATT&CK framework categorizes this vulnerability under T1499.004, which covers "Resource Exhaustion," and T1566.001, covering "Phishing with Social Engineering," as attackers may use social engineering tactics to amplify the impact of these resource exhaustion attacks. Additionally, implementing proper access controls and authentication mechanisms can significantly reduce the attack surface, as the vulnerability specifically requires anonymous call functionality to be enabled. System administrators should also consider implementing automated alerts for cache size thresholds and regularly review system logs for unusual patterns of device state entries that may indicate exploitation attempts.