CVE-2006-0739 in softphone
Summary
by MITRE
eStara SIP softphone allows remote attackers to cause a denial of service (crash) via an INVITE request with a Content-Length field that has more than 9 digits.
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Analysis
by VulDB Data Team • 07/19/2018
The CVE-2006-0739 vulnerability affects the eStara SIP softphone implementation, presenting a classic buffer overflow condition that manifests through improper input validation of SIP protocol messages. This flaw specifically targets the Content-Length field within SIP INVITE requests, where the software fails to properly handle values exceeding nine digits. The vulnerability represents a fundamental parsing error that occurs during the processing of Session Initiation Protocol messages, which are essential for establishing voice and video communication sessions over IP networks. The issue stems from the softphone's inability to correctly interpret and validate numeric fields within SIP headers, creating an exploitable condition that can be triggered by maliciously crafted SIP requests.
The technical exploitation of this vulnerability leverages the fact that the eStara SIP softphone does not implement proper bounds checking for the Content-Length header field. When an attacker sends an INVITE request containing a Content-Length value with more than nine digits, the software's parsing routine fails to handle the excessive numeric value correctly. This typically results in an integer overflow or buffer overflow condition within the application's memory management system. The flaw falls under the category of CWE-122, which describes buffer overflow conditions, and more specifically aligns with CWE-125, which deals with out-of-bounds read conditions. The vulnerability can be classified as a remote code execution risk through denial of service, as the application crashes and becomes unavailable to legitimate users, effectively preventing normal communication services.
From an operational perspective, this vulnerability presents significant risk to organizations relying on SIP-based communication systems, particularly those using the eStara softphone implementation. The remote nature of the attack means that malicious actors can exploit this weakness from outside the network perimeter, making it particularly dangerous for businesses with remote workers or those using SIP softphones for VoIP communications. The impact extends beyond simple service disruption as it can affect business continuity, customer service availability, and overall communication infrastructure reliability. Organizations may experience cascading effects where the denial of service impacts not just individual users but entire communication systems, potentially leading to lost business opportunities and damaged customer relationships. The vulnerability can be exploited as part of broader attack campaigns targeting VoIP infrastructure, aligning with ATT&CK technique T1499.004 for network denial of service attacks.
Mitigation strategies for this vulnerability should include immediate patching of the eStara softphone software to address the improper input validation issue. Network administrators should implement SIP protocol filtering and validation mechanisms to detect and block malformed INVITE requests with suspicious Content-Length values. The implementation of intrusion detection systems specifically designed for SIP traffic can help identify and prevent exploitation attempts. Organizations should also consider implementing rate limiting and connection throttling measures to prevent abuse of the vulnerability. Additionally, regular security assessments of VoIP infrastructure should be conducted to identify similar input validation weaknesses in other components of the communication ecosystem. The remediation process should also include network segmentation to limit the impact of potential exploitation and ensure that SIP traffic is properly monitored and logged for security analysis purposes.