CVE-2011-2216 in Asterisk
Summary
by MITRE
reqresp_parser.c in the SIP channel driver in Asterisk Open Source 1.8.x before 1.8.4.2 does not initialize certain strings, which allows remote attackers to cause a denial of service (NULL pointer dereference and daemon crash) via a malformed Contact header.
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Analysis
by VulDB Data Team • 12/28/2024
The vulnerability identified as CVE-2011-2216 affects the Asterisk Open Source telephony platform version 1.8.x prior to 1.8.4.2, specifically within the SIP channel driver's request response parser component. This issue manifests in the reqresp_parser.c file where certain string variables fail to be properly initialized during the processing of SIP protocol messages. The root cause of this vulnerability stems from inadequate input validation and memory management practices within the SIP parsing logic, creating a condition where uninitialized memory segments are accessed during protocol handling.
The technical flaw represents a classic null pointer dereference vulnerability that occurs when the SIP channel driver processes malformed Contact headers in SIP messages. When a remote attacker crafts a specially constructed SIP message containing a malformed Contact header, the parser attempts to access uninitialized string variables without proper validation or initialization checks. This results in the daemon crashing due to attempting to dereference a NULL pointer, effectively causing a denial of service condition that disrupts the telephony service. The vulnerability aligns with CWE-476 which describes NULL pointer dereference conditions, and demonstrates poor input sanitization practices that are commonly exploited in protocol parsing attacks.
The operational impact of this vulnerability extends beyond simple service disruption as it can be exploited remotely without authentication, making it particularly dangerous in production telephony environments. Organizations relying on Asterisk for voice communication services face potential downtime and service interruptions when this vulnerability is exploited, especially in mission-critical applications where availability is paramount. The daemon crash affects the entire SIP channel driver functionality, potentially impacting multiple concurrent calls and communication channels simultaneously, which can cascade into broader network communication failures.
Mitigation strategies for CVE-2011-2216 should prioritize immediate patching of affected Asterisk installations to version 1.8.4.2 or later, which contains the necessary fixes for proper string initialization in the SIP parser. Network administrators should implement additional monitoring and intrusion detection systems to identify malformed SIP traffic patterns that may indicate exploitation attempts. The vulnerability also highlights the importance of proper input validation and memory initialization practices in telephony applications, aligning with ATT&CK technique T1203 which covers legitimate credentials and protocol manipulation. Organizations should conduct thorough security assessments of their telephony infrastructure and implement network segmentation to limit the potential impact of such vulnerabilities in their communication systems.