CVE-2007-4753 in ST 2030 SIP phone
Summary
by MITRE
The Thomson ST 2030 SIP phone with software 1.52.1 allows remote attackers to cause a denial of service (device hang) via (1) an empty SIP message or (2) a SIP INVITE message with a malformed To header, different vectors than CVE-2007-4553.
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Analysis
by VulDB Data Team • 11/01/2017
The vulnerability identified as CVE-2007-4753 affects the Thomson ST 2030 SIP phone running software version 1.52.1, representing a critical denial of service weakness in telecommunications infrastructure. This issue demonstrates how seemingly minor protocol handling flaws can result in significant operational disruptions for voice communication systems. The vulnerability specifically targets the Session Initiation Protocol implementation within the device's firmware, where inadequate input validation creates exploitable conditions that can be leveraged remotely by malicious actors.
The technical flaw manifests through two distinct attack vectors that exploit different aspects of SIP message processing. The first vector involves sending an empty SIP message to the device, which triggers an improper state handling mechanism within the phone's SIP stack. This condition causes the device to enter an unrecoverable state where it becomes unresponsive to further SIP communications. The second vector exploits malformed To header fields within SIP INVITE messages, specifically targeting the parsing logic that processes the To header field. When the device encounters these malformed headers, the parsing routine fails to properly handle the unexpected input, leading to a device hang condition that requires manual intervention to restore normal operation.
From an operational perspective, this vulnerability presents a significant risk to organizations relying on SIP-based telephony systems, as it allows remote attackers to disrupt communication services without requiring authentication or physical access to the device. The impact extends beyond simple service interruption, as the device hang condition can persist until the phone is manually rebooted, potentially affecting business continuity and emergency communication capabilities. The vulnerability is particularly concerning because it operates at the protocol level, meaning attackers can exploit it through network-based attacks without needing to be physically present or having elevated privileges within the network.
This vulnerability aligns with CWE-20, which describes "Improper Input Validation" as a fundamental weakness in software design, and demonstrates how insufficient validation of network inputs can lead to system instability. The attack vectors also correspond to techniques documented in the MITRE ATT&CK framework under the T1499 category for Network Denial of Service, specifically targeting network infrastructure components. The device's failure to properly handle malformed SIP messages represents a classic example of insufficient error handling and input sanitization that can be exploited to achieve system compromise through denial of service attacks.
Organizations should implement immediate mitigations including network segmentation to isolate affected devices from critical network segments, deployment of intrusion detection systems to monitor for suspicious SIP traffic patterns, and application of firmware updates when available. Network administrators should also configure SIP message filtering rules to drop malformed messages before they reach the affected devices. Additionally, implementing monitoring solutions that can detect device hang conditions and automatically trigger alerts would help reduce the impact of successful exploitation attempts, while maintaining proper network access controls to limit potential attack vectors.