CVE-2003-0761 in Asterisk
Summary
by MITRE
Buffer overflow in the get_msg_text of chan_sip.c in the Session Initiation Protocol (SIP) protocol implementation for Asterisk releases before August 15, 2003, allows remote attackers to execute arbitrary code via certain (1) MESSAGE or (2) INFO requests.
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Analysis
by VulDB Data Team • 06/15/2018
The vulnerability described in CVE-2003-0761 represents a critical buffer overflow condition within the Session Initiation Protocol implementation of the Asterisk open source telephony platform. This flaw exists specifically within the chan_sip.c source file in the SIP channel driver, which handles SIP protocol communications for telephony functions. The vulnerability affects Asterisk versions released prior to August 15, 2003, making it one of the earlier and more significant security issues discovered in the Asterisk codebase. The buffer overflow occurs during the processing of SIP MESSAGE and INFO requests, which are standard SIP protocol operations used for instant messaging and information exchange between telephony endpoints. This particular implementation flaw demonstrates a classic programming error where insufficient bounds checking allows an attacker to overwrite adjacent memory locations when processing specially crafted SIP messages.
The technical nature of this vulnerability places it squarely within CWE-121, which describes buffer overflow conditions where insufficient bounds checking allows attackers to write beyond allocated memory boundaries. The flaw manifests when the get_msg_text function processes incoming SIP MESSAGE or INFO requests without proper input validation or buffer size enforcement. Attackers can exploit this by sending maliciously formatted SIP requests containing oversized message text payloads that exceed the allocated buffer space. The overflow can overwrite critical memory segments including return addresses, function pointers, or other control data structures, enabling remote code execution. This type of vulnerability represents a direct pathway for attackers to gain unauthorized control over the Asterisk server, potentially allowing them to execute arbitrary commands with the privileges of the running Asterisk process, which typically operates with system-level permissions.
The operational impact of CVE-2003-0761 extends far beyond simple service disruption, as it provides attackers with complete remote code execution capabilities on affected systems. Organizations relying on Asterisk for voice over IP communications face significant risks including unauthorized access to telephone systems, potential data breaches, and complete system compromise. The vulnerability is particularly dangerous because SIP protocol traffic flows through standard network ports, making it accessible to attackers on public networks without requiring special access privileges. This allows attackers to exploit the vulnerability from anywhere on the internet, potentially compromising telephony infrastructure used for business communications, emergency services, or critical infrastructure. The exploitation requires minimal technical skill to craft malicious SIP requests, making it a preferred target for automated attacks and malicious actors seeking to gain unauthorized access to telephony systems. The vulnerability also impacts the broader VoIP ecosystem, as compromised Asterisk servers can be used as launching points for further attacks against internal networks.
The mitigation strategy for CVE-2003-0761 requires immediate patching of affected Asterisk installations with versions released after August 15, 2003, which contain the necessary security fixes. Organizations should also implement network-level protections including firewall rules that restrict SIP protocol access to trusted networks, and consider implementing SIP protocol filtering to block malformed requests. From an operational perspective, system administrators should monitor for suspicious SIP traffic patterns and implement intrusion detection systems that can identify potential exploitation attempts. The vulnerability also highlights the importance of secure coding practices and regular security audits of telephony implementations. Organizations should consider implementing network segmentation to isolate telephony infrastructure from general network access, reducing the potential impact of successful exploitation. Additionally, maintaining current security patches and conducting regular vulnerability assessments helps prevent similar issues from occurring in other components of the telephony infrastructure. This vulnerability serves as a critical reminder of the importance of security in telephony systems, particularly as these platforms become increasingly integrated with broader network infrastructures and face growing attack surface from internet-based threats.