CVE-2022-31002 in Sofia-SIP
Summary
by MITRE • 05/31/2022
Sofia-SIP is an open-source Session Initiation Protocol (SIP) User-Agent library. Prior to version 1.13.8, an attacker can send a message with evil sdp to FreeSWITCH, which may cause a crash. This type of crash may be caused by a URL ending with `%`. Version 1.13.8 contains a patch for this issue.
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Analysis
by VulDB Data Team • 06/04/2022
The vulnerability identified as CVE-2022-31002 affects Sofia-SIP, a widely-used open-source Session Initiation Protocol library that serves as the foundation for SIP-based communication systems including FreeSWITCH. This issue represents a critical buffer overflow vulnerability that can be exploited through malformed Session Description Protocol messages, specifically those containing malicious URLs ending with the percent character. The flaw exists within the parsing logic of the SIP library when processing SDP (Session Description Protocol) content, creating a scenario where an attacker can craft specially formatted SIP messages that trigger unexpected behavior in the target system.
The technical implementation of this vulnerability stems from insufficient input validation within the Sofia-SIP library's SDP parser, which fails to properly handle malformed URL strings ending with the percent character. When FreeSWITCH processes these malicious SDP messages, the library's parsing routines encounter the malformed URL and attempt to process it without adequate bounds checking or sanitization. This leads to memory corruption that ultimately results in a system crash, effectively creating a denial of service condition that can be exploited remotely by unauthorized parties. The vulnerability is particularly concerning because it can be triggered through normal SIP communication channels, making it accessible to attackers who do not require elevated privileges or physical access to the system.
The operational impact of this vulnerability extends beyond simple service disruption, as it can be leveraged to create persistent denial of service conditions that affect VoIP infrastructure and communication systems. Organizations relying on FreeSWITCH or other systems built on Sofia-SIP are at risk of having their communication services interrupted, potentially affecting business operations, emergency services, or critical communication networks. The vulnerability demonstrates a classic buffer overflow pattern that aligns with CWE-121, which describes heap-based buffer overflow conditions that occur when insufficient bounds checking allows an attacker to write beyond allocated memory regions. From an attacker's perspective, this vulnerability maps to techniques described in the MITRE ATT&CK framework under the T1499 category, specifically for network denial of service attacks that target communication protocols.
Organizations should immediately implement the patch released in version 1.13.8 of Sofia-SIP to address this vulnerability, as the fix includes proper input validation and bounds checking for URL parsing within SDP messages. System administrators should conduct thorough vulnerability assessments to identify all instances of Sofia-SIP or FreeSWITCH installations that may be affected, particularly in environments where SIP communication is critical to operations. Additional mitigations include implementing network segmentation to limit access to SIP endpoints, deploying intrusion detection systems to monitor for suspicious SIP traffic patterns, and establishing monitoring protocols to detect potential exploitation attempts. The vulnerability also highlights the importance of maintaining up-to-date security patches and conducting regular security assessments of open-source components used in production environments to prevent similar issues from compromising communication infrastructure.