CVE-2017-9359 in Asterisk
Summary
by MITRE
The multi-part body parser in PJSIP, as used in Asterisk Open Source 13.x before 13.15.1 and 14.x before 14.4.1, Certified Asterisk 13.13 before 13.13-cert4, and other products, allows remote attackers to cause a denial of service (out-of-bounds read and application crash) via a crafted packet.
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Analysis
by VulDB Data Team • 12/26/2020
The vulnerability identified as CVE-2017-9359 represents a critical out-of-bounds read flaw within the multi-part body parser component of PJSIP, a widely-used open-source multimedia communication library. This vulnerability specifically affects Asterisk Open Source versions 13.x before 13.15.1 and 14.x before 14.4.1, as well as Certified Asterisk 13.13 before 13.13-cert4, making it a significant concern for organizations relying on these telephony platforms. The flaw exists in how the parser handles crafted multipart body data structures, creating a condition where malicious actors can manipulate the parsing process to trigger memory access violations. The vulnerability falls under CWE-125, which specifically addresses out-of-bounds read conditions, and aligns with ATT&CK technique T1499.004 for network denial of service attacks.
The technical implementation of this vulnerability exploits the parser's failure to properly validate the boundaries of multipart body segments during message processing. When a maliciously crafted packet containing malformed multipart data is received, the parser attempts to access memory locations beyond the allocated buffer boundaries, resulting in unpredictable behavior and system instability. This out-of-bounds memory access can be leveraged by remote attackers to cause application crashes, leading to complete service disruption. The parser's insufficient input validation means that it does not properly check the length and structure of incoming multipart data before attempting to process it, creating a direct path for exploitation.
From an operational standpoint, this vulnerability presents a severe risk to organizations utilizing Asterisk-based telephony systems, as it enables remote attackers to perform denial of service attacks without requiring authentication or privileged access. The impact extends beyond simple service interruption, as the application crashes can potentially lead to extended downtime, loss of communication capabilities, and disruption of critical business operations. Attackers can craft specific packet structures that will reliably trigger the out-of-bounds read condition, making this vulnerability particularly dangerous for systems handling high volumes of SIP traffic. The vulnerability's presence in multiple versions of Asterisk indicates a widespread exposure across the telecommunications infrastructure landscape.
Mitigation strategies for CVE-2017-9359 should prioritize immediate patching of affected systems to the latest stable releases that contain the fixed parser implementation. Organizations should implement network-level controls such as firewall rules and intrusion detection systems to monitor for suspicious SIP traffic patterns that might indicate exploitation attempts. The recommended approach involves updating all affected Asterisk installations to versions 13.15.1 or later for the 13.x series, and 14.4.1 or later for the 14.x series, which include the necessary input validation improvements. Additionally, system administrators should consider implementing rate limiting and traffic filtering mechanisms to reduce the attack surface and provide additional layers of defense against potential exploitation attempts.