CVE-2008-0529 in Skinny Client Control Protocol
Summary
by MITRE
Buffer overflow in the telnet server in Cisco Unified IP Phone 7906G, 7911G, 7941G, 7961G, 7970G, and 7971G running SCCP firmware might allow remote authenticated users to execute arbitrary code via a crafted command.
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Analysis
by VulDB Data Team • 08/05/2019
The vulnerability identified as CVE-2008-0529 represents a critical buffer overflow flaw within the telnet server implementation of several Cisco Unified IP Phone models including the 7906G, 7911G, 7941G, 7961G, 7970G, and 7971G devices. This security weakness resides in the Session Control Protocol SCCP firmware that governs these telephony devices, creating a pathway for malicious actors to exploit the system through network-based attacks. The flaw specifically manifests in the handling of crafted commands within the telnet server component, which serves as a remote administration interface for device configuration and management purposes.
The technical implementation of this buffer overflow vulnerability stems from inadequate input validation and memory management within the telnet server code. When authenticated users send specially crafted commands to the telnet service, the system fails to properly bounds-check the incoming data before processing it, leading to memory corruption that can be leveraged to overwrite critical program execution structures. This type of vulnerability maps directly to CWE-121, which describes heap-based buffer overflow conditions, and potentially CWE-122, which covers stack-based buffer overflows where insufficient bounds checking allows data to overwrite adjacent memory locations. The vulnerability operates at the application layer and can be exploited remotely, requiring only authentication credentials to the telnet service, which significantly broadens the attack surface.
The operational impact of this vulnerability extends beyond simple system compromise, as it enables remote code execution capabilities that could allow attackers to gain complete control over the affected IP phone devices. Once exploited, malicious actors could potentially install backdoors, modify device configurations, intercept communications, or use the compromised devices as stepping stones for broader network infiltration. This represents a significant threat to enterprise communication infrastructures, as these IP phones often serve as critical components in unified communications systems and may be connected to sensitive network segments. The vulnerability's presence in multiple device models suggests a systemic flaw in the SCCP firmware implementation that affects a substantial portion of Cisco's unified communications portfolio during that timeframe.
Organizations should implement immediate mitigations including applying the latest security patches from Cisco, disabling telnet services where possible, and implementing network segmentation to limit access to these devices. The ATT&CK framework categorizes this vulnerability under T1059.005 for remote code execution and T1078 for valid accounts, highlighting the need for robust authentication controls and network monitoring. Additional protective measures include configuring firewall rules to restrict telnet access to trusted administrative workstations only, implementing network access control lists, and establishing continuous monitoring for anomalous telnet traffic patterns. The vulnerability demonstrates the importance of secure coding practices and proper input validation in embedded systems, particularly in telephony infrastructure where device compromise can have cascading effects on business continuity and information security.