CVE-2007-3764 in Asterisk
Summary
by MITRE
The Skinny channel driver (chan_skinny) in Asterisk before 1.2.22 and 1.4.x before 1.4.8, Business Edition before B.2.2.1, AsteriskNOW before beta7, Appliance Developer Kit before 0.5.0, and s800i before 1.0.2 allows remote attackers to cause a denial of service (crash) via a certain data length value in a crafted packet, which results in an "overly large memcpy."
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Analysis
by VulDB Data Team • 01/20/2025
The vulnerability identified as CVE-2007-3764 affects the Skinny channel driver implementation within various versions of the Asterisk open source PBX system. This flaw resides in the chan_skinny module which handles communication with Cisco Skinny protocol devices including IP phones and other telephony equipment. The issue manifests when the system processes malformed packets containing an excessively large data length value that triggers improper memory handling during packet processing operations. The vulnerability impacts multiple release branches of Asterisk including the stable 1.2.x series up to 1.2.22, the development 1.4.x series up to 1.4.8, and various specialized editions such as Business Edition and AsteriskNOW. The specific version ranges indicate that this was a significant concern affecting the core telephony infrastructure components that handle voice communication protocols.
The technical root cause of this vulnerability stems from inadequate input validation within the Skinny channel driver's packet parsing logic. When processing incoming packets that contain crafted data length fields, the system fails to properly validate the size parameter before attempting memory operations. This leads to a situation where the memcpy function receives an excessively large size value that exceeds the bounds of allocated memory buffers. The improper handling of this data length value results in a buffer overflow condition that causes the application to crash and terminate unexpectedly. This type of vulnerability maps directly to CWE-121, which describes buffer overflow conditions in stack-based buffers, and also relates to CWE-122, which covers heap-based buffer overflows. The vulnerability represents a classic example of improper input validation combined with unsafe memory operations that can be exploited by remote attackers without authentication requirements.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise the entire telephony infrastructure. When exploited successfully, remote attackers can cause denial of service conditions that result in complete system crashes and service interruptions for voice communication. This is particularly concerning in enterprise environments where Asterisk serves as the primary telephony platform for business communications, as the impact can affect critical business operations and emergency communication systems. The vulnerability affects both the core Asterisk functionality and specialized deployments including business editions and appliance configurations, indicating a widespread exposure across different deployment scenarios. Organizations relying on these telephony systems may experience significant downtime and communication failures that can have cascading effects on business continuity and customer service operations.
Mitigation strategies for this vulnerability require immediate patching of affected Asterisk installations to the corrected versions that contain proper input validation and memory handling protections. System administrators should prioritize updating all affected versions including the 1.2.22 and 1.4.8 releases and their corresponding business editions and appliance variants. Network segmentation and firewall rules should be implemented to restrict access to the Skinny protocol ports, typically TCP 2000, to minimize exposure to unauthorized remote exploitation attempts. Additionally, monitoring systems should be deployed to detect unusual packet patterns and potential exploitation attempts targeting the Skinny protocol. The vulnerability also highlights the importance of implementing proper input validation and memory safety practices in telephony applications, aligning with ATT&CK technique T1499.004 which covers network disruption through denial of service attacks. Organizations should also consider implementing intrusion detection systems specifically configured to monitor for Skinny protocol anomalies and potential exploitation attempts. Regular security assessments and vulnerability scanning should be conducted to identify any remaining unpatched systems within the telephony infrastructure and ensure comprehensive protection against similar memory corruption vulnerabilities.