CVE-2022-31003 in Sofia-SIP
Summary
by MITRE • 06/01/2022
Sofia-SIP is an open-source Session Initiation Protocol (SIP) User-Agent library. Prior to version 1.13.8, when parsing each line of a sdp message, `rest = record + 2` will access the memory behind `\0` and cause an out-of-bounds write. An attacker can send a message with evil sdp to FreeSWITCH, causing a crash or more serious consequence, such as remote code execution. Version 1.13.8 contains a patch for this issue.
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Analysis
by VulDB Data Team • 06/04/2022
The vulnerability CVE-2022-31003 affects Sofia-SIP, an open-source Session Initiation Protocol User-Agent library widely used in VoIP implementations including FreeSWITCH. This issue represents a critical memory corruption flaw that exists in versions prior to 1.13.8, making it a significant concern for organizations relying on SIP-based communication systems. The vulnerability stems from improper bounds checking during SDP (Session Description Protocol) message parsing, specifically when processing individual lines within the SDP record structure.
The technical flaw manifests in the SDP parsing routine where the code executes `rest = record + 2` without adequate validation of the buffer boundaries. This operation accesses memory locations that extend beyond the legitimate buffer limits, creating an out-of-bounds write condition that can be exploited by malicious actors. The vulnerability is particularly dangerous because SDP messages are commonly transmitted during SIP session establishment and modification, making this attack vector highly accessible during normal communication flows. The memory corruption occurs when the parser encounters specially crafted SDP content that triggers the unsafe memory access pattern.
The operational impact of this vulnerability extends beyond simple system crashes, presenting potential for remote code execution as demonstrated in the FreeSWITCH environment. Attackers can construct malicious SDP messages that, when processed by vulnerable Sofia-SIP implementations, trigger the out-of-bounds write condition. This could result in denial of service attacks that disrupt communication services or more severe compromise scenarios where attackers leverage the memory corruption to execute arbitrary code on affected systems. The vulnerability affects not only FreeSWITCH but any system utilizing vulnerable versions of Sofia-SIP, creating a widespread risk across VoIP infrastructure. Organizations using SIP-based telephony systems, unified communications platforms, and VoIP gateways face significant exposure to this threat.
Mitigation strategies should prioritize immediate upgrade to Sofia-SIP version 1.13.8 or later, which contains the necessary patch addressing the out-of-bounds write vulnerability. Network administrators should implement SDP message filtering and validation mechanisms as additional defensive layers, particularly when processing external SIP communications. The vulnerability aligns with CWE-787 Out-of-bounds Write, a common weakness category that frequently appears in network protocol implementations. From an ATT&CK framework perspective, this vulnerability maps to techniques involving command and control communications, specifically T1071.004 Application Layer Protocol: SIP, and T1059 Command and Scripting Interpreter, as exploitation could enable remote code execution. Organizations should also consider implementing intrusion detection systems capable of identifying malformed SDP content and establishing monitoring protocols for unusual SIP traffic patterns that might indicate exploitation attempts.