CVE-2012-2416 in Asterisk
Summary
by MITRE
chan_sip.c in the SIP channel driver in Asterisk Open Source 1.8.x before 1.8.11.1 and 10.x before 10.3.1 and Asterisk Business Edition C.3.x before C.3.7.4, when the trustrpid option is enabled, allows remote authenticated users to cause a denial of service (daemon crash) by sending a SIP UPDATE message that triggers a connected-line update attempt without an associated channel.
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Analysis
by VulDB Data Team • 12/22/2024
The vulnerability identified as CVE-2012-2416 represents a critical denial of service flaw within the SIP channel driver of Asterisk Open Source and Business Edition systems. This issue specifically affects versions prior to the mentioned secure releases, creating a scenario where authenticated remote attackers can exploit the system's handling of SIP UPDATE messages to cause daemon crashes. The vulnerability manifests when the trustrpid option is enabled, which is a configuration setting that controls how Asterisk processes certain SIP headers and channel information. The flaw demonstrates a fundamental weakness in input validation and error handling within the SIP channel driver's processing logic, where the system fails to properly validate the presence of an associated channel before attempting a connected-line update operation.
The technical exploitation of this vulnerability occurs through a carefully crafted SIP UPDATE message that triggers the daemon to attempt a connected-line update without having a valid channel context to reference. This creates a condition where the system attempts to access memory or resources that do not exist or are not properly initialized, leading to a segmentation fault or similar memory access violation that results in the Asterisk daemon crashing and requiring manual restart. The flaw is particularly dangerous because it can be triggered by authenticated users who have already established SIP connections to the system, meaning that an attacker with valid credentials or the ability to perform SIP registration can cause service disruption without requiring additional privileges or complex attack vectors.
From a cybersecurity perspective, this vulnerability aligns with CWE-125, which describes out-of-bounds read conditions, and CWE-248, which covers exposure of uninitialized variables. The attack pattern follows the MITRE ATT&CK framework's methodology for privilege escalation and denial of service techniques, specifically targeting the service availability aspect of the attack surface. The vulnerability demonstrates poor defensive programming practices where the system does not properly validate preconditions before executing operations that require specific resource states. The operational impact extends beyond simple service disruption, as Asterisk systems often serve as critical communication infrastructure for businesses, telecommunications providers, and VoIP services, making this vulnerability particularly concerning for organizations that rely on these systems for mission-critical communications.
Organizations affected by this vulnerability should immediately implement the recommended patches and updates to their Asterisk installations, ensuring that all systems are upgraded to versions that contain the fix for this specific issue. The trustrpid option should be carefully evaluated for its necessity and potentially disabled if it is not required for specific business operations, as this configuration parameter directly enables the vulnerable code path. Additionally, network segmentation and access controls should be strengthened to limit the scope of potential attackers who might gain authenticated access to the SIP infrastructure. Security monitoring should include detection of unusual SIP UPDATE message patterns and connection attempts that might indicate exploitation attempts. System administrators should also consider implementing automated restart procedures or failover mechanisms to minimize service disruption should exploitation occur, while maintaining detailed logging of SIP traffic for forensic analysis purposes.