CVE-2007-2270 in SPA941
Summary
by MITRE
The Linksys SPA941 VoIP Phone allows remote attackers to cause a denial of service (device reboot) via a 0377 (0xff) character in the From header, and possibly certain other locations, in a SIP INVITE request.
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Analysis
by VulDB Data Team • 09/08/2024
The CVE-2007-2270 vulnerability affects the Linksys SPA941 VoIP phone, representing a critical denial of service flaw that can be exploited remotely by attackers. This vulnerability specifically targets the device's handling of SIP (Session Initiation Protocol) INVITE requests, which are fundamental to establishing voice communication sessions over IP networks. The vulnerability manifests when the device receives a SIP INVITE request containing a 0377 (0xff) character in the From header field or potentially other locations within the SIP message structure. The presence of this particular character sequence triggers an unexpected behavior in the device's SIP parser, leading to a complete device reboot and subsequent denial of service for legitimate users.
The technical flaw stems from inadequate input validation within the SPA941's SIP message processing subsystem. When the device encounters the 0377 character, which represents a null byte or extended ASCII character in the SIP header, the parsing logic fails to properly handle this malformed input. This parsing failure results in a buffer overflow or memory corruption condition that causes the device's operating system to crash and automatically reboot. The vulnerability demonstrates a classic weakness in protocol implementation where devices fail to sanitize input data before processing, allowing malicious actors to craft specially formatted SIP requests that exploit this parsing gap.
The operational impact of this vulnerability extends beyond simple service disruption, as it can be exploited by attackers to repeatedly reboot the device, creating persistent denial of service conditions that can severely impact business communications. In enterprise environments where VoIP infrastructure is critical for operations, such an attack can lead to significant productivity losses and potential financial impacts. The vulnerability is particularly concerning because it requires no authentication or privileged access to exploit, making it accessible to anyone who can send SIP messages to the device. This remote exploit capability means that attackers can target devices from outside the network perimeter, potentially affecting organizations that have not properly secured their VoIP infrastructure or implemented appropriate network segmentation.
Mitigation strategies for this vulnerability should include immediate firmware updates from Linksys that address the SIP parsing flaw and implement proper input validation for all SIP message headers. Network administrators should also implement SIP message filtering and rate limiting mechanisms to prevent malformed requests from reaching the VoIP phones. Additionally, the use of network segmentation and firewalls can help limit exposure by restricting direct access to VoIP devices from untrusted networks. This vulnerability aligns with CWE-129, which covers improper validation of input boundaries, and relates to ATT&CK technique T1499.004 for network denial of service, highlighting the importance of proper input sanitization in network infrastructure devices. Organizations should also consider implementing intrusion detection systems that can monitor for suspicious SIP traffic patterns and alert administrators to potential exploitation attempts.