CVE-2007-4280 in Asterisk
Summary
by MITRE
The Skinny channel driver (chan_skinny) in Asterisk Open Source before 1.4.10, AsteriskNOW before beta7, Appliance Developer Kit before 0.7.0, and Appliance s800i before 1.0.3 allows remote authenticated users to cause a denial of service (application crash) via a CAPABILITIES_RES_MESSAGE packet with a capabilities count larger than the capabilities_res_message array population.
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Analysis
by VulDB Data Team • 07/21/2021
The vulnerability described in CVE-2007-4280 affects the Skinny channel driver implementation within Asterisk Open Source software, specifically targeting versions prior to 1.4.10 and related products including AsteriskNOW beta7 and various appliance versions. This flaw exists within the handling of CAPABILITIES_RES_MESSAGE packets, which are part of the Skinny Client Control Protocol used for communication between IP phones and Asterisk servers. The Skinny protocol was developed by Cisco and implemented in Asterisk to support Cisco IP phone integration, making this vulnerability particularly significant for organizations relying on VoIP infrastructure.
The technical flaw manifests when the chan_skinny driver processes a CAPABILITIES_RES_MESSAGE packet containing a capabilities count value that exceeds the actual size of the capabilities_res_message array allocated in memory. This condition creates a classic buffer overflow scenario where the application attempts to write beyond the bounds of the allocated memory space. The vulnerability occurs during the parsing phase of the Skinny protocol communication, where the system does not properly validate the count field against the array dimensions before proceeding with memory operations. This type of flaw falls under CWE-129: Improper Validation of Array Index, which is classified as a weakness in input validation and memory management.
The operational impact of this vulnerability is a remote authenticated denial of service condition that can cause the Asterisk application to crash and restart automatically. Since the vulnerability requires only authenticated access to the system, it represents a significant risk in environments where legitimate users might have access to the VoIP infrastructure. Attackers who can authenticate to the Asterisk system can exploit this flaw to repeatedly crash the application, effectively disrupting voice communication services for all users. The DoS condition is particularly damaging in enterprise environments where Asterisk serves as a critical component of the communication infrastructure, potentially leading to business disruption and loss of productivity.
Mitigation strategies for this vulnerability involve immediate patching of affected systems to versions 1.4.10 and later, which contain the necessary fixes for proper array boundary validation. Organizations should also implement network segmentation to limit access to the Asterisk server to authorized users only, reducing the attack surface. The implementation of proper input validation controls and bounds checking mechanisms should be enforced throughout the application codebase to prevent similar issues. From a security framework perspective, this vulnerability aligns with ATT&CK technique T1499.004: Endpoint Denial of Service, which focuses on disrupting services through resource exhaustion or application crashes. System administrators should also consider implementing monitoring and alerting mechanisms to detect unusual application restart patterns that might indicate exploitation attempts. Additionally, regular security assessments of VoIP infrastructure components are recommended to identify and remediate similar vulnerabilities before they can be exploited by malicious actors.