CVE-2007-4459 in IP Phone
Summary
by MITRE
Cisco IP Phone 7940 and 7960 with P0S3-08-6-00 firmware, and other SIP firmware before 8.7(0), allows remote attackers to cause a denial of service (device reboot) via (1) a certain sequence of 10 invalid SIP INVITE and OPTIONS messages; or (2) a certain invalid SIP INVITE message that contains a remote tag, followed by a certain set of two related SIP OPTIONS messages.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 11/24/2024
The vulnerability identified as CVE-2007-4459 represents a critical denial of service flaw affecting Cisco IP Phone 7940 and 7960 devices running specific firmware versions. This vulnerability resides within the Session Initiation Protocol implementation of these telephony devices, specifically impacting the processing of SIP INVITE and OPTIONS messages. The flaw stems from inadequate input validation and error handling mechanisms within the device's SIP stack, which fails to properly manage malformed or invalid SIP signaling messages that could be crafted by remote attackers. The vulnerability affects firmware versions prior to P0S3-08-6-00 and SIP firmware versions before 8.7(0), indicating a widespread exposure across multiple device generations and software releases.
The technical exploitation of this vulnerability occurs through carefully crafted SIP message sequences that exploit memory management and state transition flaws within the Cisco IP Phone firmware. Attackers can trigger device reboots by sending either a specific sequence of ten invalid SIP INVITE and OPTIONS messages or by constructing a particular invalid SIP INVITE message containing a remote tag followed by two related SIP OPTIONS messages. This exploitation pattern demonstrates a buffer over-read or memory corruption issue where the device's SIP parser fails to properly validate message headers and content before processing them, leading to unpredictable behavior that ultimately results in system instability and complete device reboot. The vulnerability operates at the application layer of the network stack, leveraging the SIP protocol's signaling mechanisms to manipulate device state through crafted message sequences.
The operational impact of this vulnerability extends beyond simple service disruption to potentially enable broader network availability attacks against voice infrastructure. Organizations relying on Cisco IP Phone deployments for business communications face significant risks as attackers could repeatedly exploit this flaw to maintain persistent denial of service conditions, effectively rendering critical communication endpoints unavailable to legitimate users. The vulnerability's remote nature means that attackers need not have physical access to devices or direct network connectivity to the phones themselves, as the attack can be launched from anywhere on the network. This characteristic aligns with ATT&CK technique T1499.004 for network denial of service and represents a classic example of a protocol-level attack that can be amplified through automated scanning tools. The vulnerability affects enterprise voice communication systems and could potentially disrupt business operations, particularly in mission-critical environments where reliable voice communication is essential.
Mitigation strategies for CVE-2007-4459 require immediate firmware upgrades to versions that address the underlying SIP parsing vulnerabilities, specifically targeting firmware releases P0S3-08-6-00 or later for the affected IP Phone models. Network administrators should implement SIP message filtering and rate limiting mechanisms at network boundaries to prevent malicious message sequences from reaching vulnerable devices, though this approach may impact legitimate network traffic. Device-specific mitigations include disabling unnecessary SIP features and implementing proper access controls to limit exposure of SIP endpoints to untrusted networks. The vulnerability's classification as a buffer overflow or memory corruption issue places it within CWE-129 and CWE-131 categories, representing weaknesses in input validation and memory handling that require both immediate remediation and long-term architectural improvements. Organizations should also consider implementing network segmentation strategies to isolate voice infrastructure from general network traffic, reducing the attack surface and limiting the potential impact of such vulnerabilities. Regular security assessments and vulnerability management processes should be implemented to identify and remediate similar issues before they can be exploited by threat actors.