CVE-2014-8416 in Asterisk
Summary
by MITRE
Use-after-free vulnerability in the PJSIP channel driver in Asterisk Open Source 12.x before 12.7.1 and 13.x before 13.0.1, when using the res_pjsip_refer module, allows remote attackers to cause a denial of service (crash) via an in-dialog INVITE with Replaces message, which triggers the channel to be hung up.
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Analysis
by VulDB Data Team • 02/27/2022
The CVE-2014-8416 vulnerability represents a critical use-after-free condition within the PJSIP channel driver of Asterisk Open Source versions prior to 12.7.1 and 13.0.1. This flaw specifically manifests when the res_pjsip_refer module is actively employed, creating a scenario where remote attackers can manipulate the signaling process to trigger system instability. The vulnerability exploits the improper handling of memory references during SIP session management, particularly when processing in-dialog INVITE requests containing Replaces headers that instruct the system to terminate existing sessions.
The technical implementation of this vulnerability stems from inadequate memory management practices within the Asterisk signaling stack. When a malicious actor crafts an in-dialog INVITE message with a Replaces header, the system processes this request through the PJSIP channel driver which fails to properly validate or manage the memory references associated with the channel being replaced. This leads to a situation where the system attempts to access memory that has already been freed, resulting in undefined behavior and system crashes. The flaw operates at the application layer of the SIP protocol stack, specifically targeting the session management components that handle refer operations and dialog termination.
The operational impact of this vulnerability extends beyond simple denial of service, as it provides attackers with a reliable method to disrupt communication services within VoIP infrastructure. Organizations relying on Asterisk for their telephony services face significant risk of service interruption, particularly in environments where continuous availability is critical. The remote nature of the attack means that adversaries can exploit this vulnerability from outside the network perimeter without requiring authentication or privileged access. This characteristic aligns with attack patterns documented in the MITRE ATT&CK framework under the 'Command and Control' and 'Remote Services' domains, where adversaries leverage protocol-level vulnerabilities to maintain persistent access or disrupt service availability.
The vulnerability's exploitation requires minimal technical expertise and can be automated, making it particularly dangerous in production environments. The use-after-free condition creates a stable crash scenario that can be repeatedly triggered, enabling attackers to maintain sustained denial of service conditions. Organizations implementing Asterisk solutions should consider the broader implications of this vulnerability within their network security posture, as it represents a fundamental memory safety issue that could potentially be extended to more sophisticated attack vectors. The flaw demonstrates the importance of proper input validation and memory management practices in telephony applications, aligning with CWE-416 which categorizes use-after-free conditions as critical memory safety vulnerabilities.
Mitigation strategies for CVE-2014-8416 primarily focus on immediate software updates to patched versions of Asterisk, specifically versions 12.7.1 and 13.0.1 or later. Network administrators should implement proper firewall rules to restrict access to SIP signaling ports and consider deploying intrusion detection systems that can identify suspicious INVITE requests with Replaces headers. Additionally, organizations should conduct comprehensive vulnerability assessments of their telephony infrastructure to identify any other potentially affected components that might be running older versions of Asterisk or related modules. The implementation of rate limiting and session monitoring mechanisms can provide additional defense-in-depth measures against exploitation attempts.