CVE-2007-5636 in IP Softphone 2050
Summary
by MITRE
Buffer overflow in the Nortel UNIStim IP Softphone 2050 allows remote attackers to cause a denial of service (application abort) and possibly execute arbitrary code via a flood of invalid characters to the RTCP port (5678/udp) that triggers a Windows error message, aka "extraneous messaging."
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Analysis
by VulDB Data Team • 02/13/2025
The vulnerability identified as CVE-2007-5636 represents a critical buffer overflow flaw within the Nortel UNIStim IP Softphone 2050 implementation. This security weakness specifically manifests when the affected softphone receives malformed data through the RTCP port designated at 5678/udp. The flaw stems from inadequate input validation mechanisms that fail to properly handle excessive character sequences, creating a condition where memory allocation becomes corrupted. The vulnerability falls under CWE-121, which categorizes buffer overflow conditions where insufficient space is allocated for data storage, and aligns with ATT&CK technique T1203, involving the exploitation of input validation weaknesses to achieve arbitrary code execution or denial of service outcomes.
The technical implementation of this vulnerability exploits the softphone's handling of real-time transport control protocol messages, which are essential for voice communication quality monitoring and feedback in VoIP environments. When attackers flood the designated RTCP port with malformed packets containing excessive invalid characters, the application's memory management routines become overwhelmed. This overflow condition triggers a Windows error message that ultimately results in application termination, creating a denial of service scenario that disrupts legitimate voice communication services. The flaw's remote exploitability means attackers can initiate the attack from any network location without requiring physical access to the target system, making it particularly dangerous in enterprise environments where VoIP infrastructure is extensively deployed.
The operational impact of this vulnerability extends beyond simple service disruption to potentially enable remote code execution, representing a significant threat to enterprise communication networks. Organizations utilizing Nortel UNIStim IP Softphone 2050 devices face substantial risk of unauthorized access and system compromise, especially when these devices operate in unsecured network environments. The vulnerability's exploitation can lead to complete system compromise, allowing attackers to gain persistent access to network resources and potentially escalate privileges to achieve broader network infiltration. This represents a critical concern for organizations relying on VoIP infrastructure for business communications, as the attack surface includes not only the affected softphone but also any network components that may be impacted by the resulting service disruption.
Mitigation strategies for CVE-2007-5636 should focus on immediate network segmentation and access control measures to prevent unauthorized access to the RTCP port. Network administrators should implement firewall rules to restrict access to port 5678/udp from untrusted networks and establish monitoring protocols to detect anomalous traffic patterns indicative of exploitation attempts. The implementation of intrusion detection systems with signature-based detection capabilities can help identify and block malicious traffic targeting this vulnerability. Additionally, organizations should consider network access control measures that limit the exposure of VoIP infrastructure to external threats. Security patches or firmware updates from Nortel should be implemented as soon as available, though the age of this vulnerability suggests that support may have been discontinued. Organizations should also conduct thorough network audits to identify all instances of affected software and ensure that proper network segmentation prevents lateral movement if exploitation occurs. The vulnerability's classification as a remote code execution threat necessitates comprehensive incident response planning and network monitoring protocols to detect and respond to potential exploitation attempts.