CVE-2012-3553 in Asterisk
Summary
by MITRE
chan_skinny.c in the Skinny (aka SCCP) channel driver in Asterisk Open Source 10.x before 10.5.1 allows remote authenticated users to cause a denial of service (NULL pointer dereference and daemon crash) by sending a Station Key Pad Button message and closing a connection in off-hook mode, a related issue to CVE-2012-2948.
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Analysis
by VulDB Data Team • 03/25/2021
The vulnerability identified as CVE-2012-3553 affects the Skinny Client Control Protocol channel driver implementation within Asterisk Open Source versions 10.x prior to 10.5.1. This flaw resides in the chan_skinny.c file and represents a significant security concern for telecommunications infrastructure relying on Asterisk for voice communication services. The issue manifests as a denial of service condition that can be triggered by remote authenticated users, making it particularly dangerous in environments where proper access controls may not be fully enforced. The vulnerability specifically targets the handling of Station Key Pad Button messages within the SCCP protocol implementation, creating a pathway for attackers to disrupt service availability.
The technical mechanism behind this vulnerability involves a NULL pointer dereference condition that occurs when the Skinny channel driver processes certain message sequences. When an authenticated user sends a Station Key Pad Button message and subsequently closes a connection while the phone remains in off-hook mode, the system fails to properly validate pointer references before attempting to access them. This particular sequence of events causes the Asterisk daemon to crash and restart, effectively creating a denial of service condition that impacts all users relying on the affected telephony services. The flaw is categorized as a CWE-476_NULL_pointer_dereference, which is a well-documented weakness in software development where code attempts to access a null pointer reference without proper validation.
The operational impact of this vulnerability extends beyond simple service disruption as it can affect entire telephony systems that depend on Asterisk for call handling and management. Organizations using affected Asterisk versions may experience unexpected service outages, particularly during peak usage periods when multiple simultaneous connections could be exploited. The vulnerability's relationship to CVE-2012-2948 demonstrates a pattern of similar flaws within the same codebase, suggesting potential systemic issues in how the Skinny channel driver handles connection states and message processing. This creates a broader security concern for organizations that may be running multiple vulnerable components within their telephony infrastructure.
Mitigation strategies for CVE-2012-3553 should prioritize immediate patching of affected Asterisk installations to version 10.5.1 or later, which contains the necessary code modifications to prevent the NULL pointer dereference condition. Network administrators should also implement additional monitoring and logging capabilities to detect unusual patterns of Station Key Pad Button message sequences that could indicate exploitation attempts. The ATT&CK framework categorizes this vulnerability under T1499.004_Cloud_Compute_Disruption, as it affects the availability of telephony services through daemon crashes. Organizations should also consider implementing network segmentation to limit access to the Skinny protocol endpoints and establish more robust authentication mechanisms for telephony systems. Regular security assessments of telephony infrastructure and adherence to security best practices for VoIP implementations will help prevent similar vulnerabilities from emerging in the future, particularly given the historical pattern of related issues within the same codebase that were addressed through the 10.5.1 release.