CVE-2008-0526 in Skinny Client Control Protocol
Summary
by MITRE
Cisco Unified IP Phone 7940, 7940G, 7960, and 7960G running SCCP firmware allows remote attackers to cause a denial of service (reboot) via a long ICMP echo request (ping) packet.
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Analysis
by VulDB Data Team • 08/05/2019
The vulnerability identified as CVE-2008-0526 affects Cisco Unified IP Phone models 7940, 7940G, 7960, and 7960G when operating with SCCP firmware. These telephony devices are widely deployed in enterprise environments for voice communication and represent critical components of unified communications infrastructure. The vulnerability stems from insufficient input validation within the device's network processing capabilities, specifically in how the system handles ICMP echo request packets. This flaw exists at the network protocol level where the phone fails to properly sanitize incoming ping requests, creating a condition that can be exploited by remote attackers to disrupt service availability. The vulnerability is categorized under CWE-129, which represents Improper Validation of Array Index, as the device does not adequately validate the length of incoming ICMP data, leading to potential buffer overflow conditions.
The technical exploitation of this vulnerability occurs when a remote attacker sends an ICMP echo request packet containing an abnormally long payload to the affected IP phone. The device's firmware processes this malformed packet without proper bounds checking, causing the system to crash and subsequently reboot. This denial of service condition affects the availability of voice communication services within the enterprise network, as the phone becomes temporarily inaccessible to users. The attack vector is particularly concerning because it requires no authentication or specialized privileges, making it accessible to any remote attacker who can reach the device's network interface. The vulnerability demonstrates a classic buffer over-read condition where the system attempts to process data beyond allocated memory boundaries, leading to system instability and forced restart.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise business continuity in mission-critical environments. Organizations relying on Cisco IP phones for voice communication may experience significant downtime during attacks, affecting employee productivity and customer service capabilities. In large enterprise networks, multiple affected devices could result in cascading failures that impact entire communication infrastructures. The vulnerability also represents a potential precursor to more sophisticated attacks, as the device reboot process may create temporary network instability that could be exploited by attackers to gain further access to the network. According to ATT&CK framework, this vulnerability aligns with T1499.004 - Endpoint Denial of Service, which covers techniques specifically targeting device availability through network-based attacks.
Mitigation strategies for CVE-2008-0526 should focus on network-level protections and firmware updates. Organizations should implement access control lists and firewall rules to block ICMP traffic to affected devices, particularly incoming echo requests that could trigger the vulnerability. Cisco released firmware updates addressing this issue, and network administrators should immediately apply these patches to all affected phone models. Additionally, implementing network segmentation and monitoring solutions can help detect anomalous ICMP traffic patterns that may indicate attempted exploitation. The vulnerability highlights the importance of network device hardening practices and proper input validation in embedded systems. Organizations should also consider deploying intrusion detection systems that can identify and alert on suspicious ICMP traffic patterns, as the attack can be automated and repeated to maintain persistent denial of service conditions. Regular security assessments and vulnerability scanning should include verification of firmware versions to ensure all devices are protected against known vulnerabilities.