CVE-2012-2948 in Asterisk
Summary
by MITRE
chan_skinny.c in the Skinny (aka SCCP) channel driver in Certified Asterisk 1.8.11-cert before 1.8.11-cert2 and Asterisk Open Source 1.8.x before 1.8.12.1 and 10.x before 10.4.1 allows remote authenticated users to cause a denial of service (NULL pointer dereference and daemon crash) by closing a connection in off-hook mode.
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Analysis
by VulDB Data Team • 08/15/2024
The vulnerability identified as CVE-2012-2948 affects the Skinny Channel Driver implementation within Asterisk communication platforms, specifically targeting versions prior to critical security patches. This flaw exists within the chan_skinny.c component that handles Skinny Client Control Protocol connections, which are commonly used for integrating with Cisco IP phones and other compatible devices. The vulnerability manifests when authenticated remote attackers exploit a specific condition involving connection handling during off-hook states, creating a scenario that leads to daemon instability and system unavailability.
The technical root cause of this vulnerability stems from inadequate input validation and error handling within the Skinny channel driver's connection management logic. When a connection is closed while in an off-hook state, the system fails to properly validate pointer references before attempting to process the termination sequence. This results in a NULL pointer dereference condition that crashes the Asterisk daemon process, effectively rendering the communication platform unavailable to legitimate users. The flaw represents a classic denial of service vulnerability that operates through legitimate authentication mechanisms, making it particularly dangerous as it can be exploited by authenticated users who already possess valid credentials.
The operational impact of CVE-2012-2948 extends beyond simple service disruption to potentially compromise enterprise communication infrastructure. Organizations relying on Asterisk for voice communications face significant risks when this vulnerability remains unpatched, as attackers with valid user accounts can systematically crash the system and prevent legitimate calls from being processed. The vulnerability affects both certified Asterisk installations and open source versions, creating widespread exposure across different deployment scenarios. Network administrators must consider that the attack vector requires only authenticated access, meaning that internal threats or compromised accounts could trigger system outages. This vulnerability aligns with CWE-476 which identifies NULL pointer dereference as a critical weakness in software systems.
Mitigation strategies for this vulnerability primarily focus on applying the recommended security patches that address the pointer validation issues in the Skinny channel driver. System administrators should immediately upgrade to Asterisk versions 1.8.11-cert2, 1.8.12.1, or 10.4.1 respectively, depending on their installation type. Additional protective measures include implementing network segmentation to limit access to the Asterisk server, enforcing strict authentication controls, and monitoring connection states for unusual patterns that might indicate exploitation attempts. The ATT&CK framework categorizes this vulnerability under privilege escalation and denial of service techniques, as it allows attackers to leverage existing authenticated sessions to cause system instability. Organizations should also consider implementing intrusion detection systems that can identify abnormal connection termination patterns and alert administrators to potential exploitation attempts.
The broader implications of this vulnerability highlight the critical importance of proper input validation in telephony systems, particularly those handling real-time communication protocols. The flaw demonstrates how seemingly minor implementation errors in connection management can result in significant service disruptions, emphasizing the need for comprehensive security testing of communication infrastructure components. Security teams must recognize that vulnerabilities in voice communication platforms can have cascading effects on business continuity, especially in environments where reliable phone systems are essential for operations. Regular security assessments and prompt patch management remain crucial defenses against such exploitation vectors that can compromise the stability and availability of critical communication services.