CVE-2017-6656 in IP Phone 8800
Summary
by MITRE
A vulnerability in Session Initiation Protocol (SIP) call handling of Cisco IP Phone 8800 Series devices could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition due to the SIP process unexpectedly restarting. All active phone calls are dropped as the SIP process restarts. More Information: CSCvc29353. Known Affected Releases: 11.0(0.1). Known Fixed Releases: 11.0(0)MP2.153 11.0(0)MP2.62.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 12/26/2020
The vulnerability identified as CVE-2017-6656 affects Cisco IP Phone 8800 Series devices and represents a significant denial of service weakness in the Session Initiation Protocol handling mechanism. This flaw resides within the SIP process of these telephony devices, creating an exploitable condition that allows remote attackers to disrupt normal communication operations without requiring authentication credentials. The vulnerability specifically impacts the SIP call handling functionality, which forms the backbone of voice communication in enterprise environments where these devices are commonly deployed.
The technical nature of this vulnerability stems from improper handling of SIP messages within the device's processing pipeline, causing the SIP service to crash and restart unexpectedly when certain malformed or crafted SIP requests are received. This process restart results in immediate termination of all active phone calls, effectively creating a complete disruption of communication services. The flaw manifests as a failure in the SIP stack's error handling mechanisms, where the device fails to properly validate incoming SIP traffic and instead responds by restarting its core communication process. This behavior aligns with CWE-248, which addresses "Uncaught Exception" conditions in software implementations, particularly in network protocol handling components.
From an operational perspective, this vulnerability presents a substantial risk to enterprise communication infrastructure, as it can be exploited remotely by attackers without requiring any privileged access or authentication credentials. The impact extends beyond simple service interruption, as the sudden termination of active calls can disrupt critical business operations, emergency communications, and collaborative workflows that depend on reliable voice services. Organizations using Cisco IP Phone 8800 Series devices face potential operational downtime and productivity losses, particularly in environments where continuous communication is essential for business continuity. The vulnerability's remote exploitability means that attackers can target these devices from outside the network perimeter, making it particularly dangerous for organizations with limited network segmentation.
The mitigation strategy for this vulnerability involves applying the vendor-provided security patches and firmware updates that address the SIP processing flaw in the affected Cisco IP Phone 8800 Series devices. Cisco has released fixed versions including 11.0(0)MP2.153 and 11.0(0)MP2.62, which contain the necessary code modifications to properly handle SIP messages and prevent the unintended process restart. Network administrators should prioritize the deployment of these updates across all affected devices while implementing proper network monitoring to detect potential exploitation attempts. This vulnerability demonstrates the importance of maintaining up-to-date firmware in networked telephony equipment and aligns with ATT&CK technique T1499.004, which covers "Cloud Service Disruption" through denial of service mechanisms. Organizations should also consider implementing network segmentation and access controls to limit potential attack surfaces for these devices while ensuring proper patch management procedures are in place to address similar vulnerabilities in the future.