CVE-2018-14767 in Kamailio
Summary
by MITRE
In Kamailio before 5.0.7 and 5.1.x before 5.1.4, a crafted SIP message with a double "To" header and an empty "To" tag causes a segmentation fault and crash. The reason is missing input validation in the "build_res_buf_from_sip_req" core function. This could result in denial of service and potentially the execution of arbitrary code.
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Analysis
by VulDB Data Team • 04/27/2023
The vulnerability identified as CVE-2018-14767 represents a critical denial of service weakness in Kamailio, a widely deployed open source SIP server software that serves as a foundational component in telecommunications infrastructure. This flaw exists in versions prior to 5.0.7 and 5.1.x prior to 5.1.4, making it a persistent threat across multiple release lines of this essential telephony platform. The vulnerability stems from inadequate input validation mechanisms within the core SIP processing functionality, specifically in the build_res_buf_from_sip_req function which handles the construction of response buffers from incoming SIP requests. The flaw manifests when a malicious actor crafts a SIP message containing a double "To" header with an empty "To" tag, a seemingly innocuous manipulation that triggers catastrophic system behavior.
The technical exploitation of this vulnerability occurs through a precise manipulation of SIP protocol headers that bypasses normal validation procedures. When Kamailio processes a SIP message containing the crafted double "To" header with an empty tag, the build_res_buf_from_sip_req function fails to properly validate the input structure, leading to a segmentation fault during memory access operations. This memory corruption results in an immediate system crash and complete service disruption. The vulnerability falls under CWE-121, which categorizes buffer overflow conditions, and more specifically aligns with CWE-125, representing out-of-bounds read vulnerabilities. The underlying issue demonstrates a classic improper input validation problem where the software assumes valid input structures without proper sanitization checks.
From an operational impact perspective, this vulnerability poses significant risks to telecommunications networks that rely on Kamailio as their SIP server infrastructure. The denial of service condition can be triggered remotely with minimal technical expertise, making it an attractive target for attackers seeking to disrupt communication services. Network operators and service providers utilizing vulnerable Kamailio versions face potential service interruptions that could affect hundreds or thousands of concurrent users depending on the scale of deployment. The vulnerability's potential for arbitrary code execution, while not definitively confirmed, remains a serious concern given the nature of segmentation faults in memory management systems. This capability could enable attackers to gain unauthorized access to the underlying system, potentially escalating to full system compromise. The vulnerability maps to ATT&CK technique T1499.004, which covers network denial of service attacks, and T1059.007, representing command and scripting interpreter usage through Windows Command Shell.
The mitigation strategy for CVE-2018-14767 centers on immediate software version upgrades to patched releases of Kamailio. Organizations must ensure deployment of versions 5.0.7 or later, and 5.1.4 or later to address this vulnerability. System administrators should implement comprehensive patch management procedures to verify all Kamailio installations across their network infrastructure. Additional protective measures include implementing SIP message filtering rules at network boundaries to detect and block malformed SIP headers, deploying intrusion detection systems specifically configured to monitor for this vulnerability signature, and conducting thorough security audits of all SIP server configurations. Network segmentation and access controls should be strengthened to limit exposure of vulnerable Kamailio instances to untrusted networks. The remediation process must also include comprehensive testing of patched environments to ensure that the vulnerability fix does not introduce compatibility issues with existing SIP service configurations. Organizations should establish monitoring protocols to detect potential exploitation attempts and maintain detailed incident response procedures specifically addressing SIP-based denial of service attacks.