CVE-2008-3263 in Asterisk
Summary
by MITRE
The IAX2 protocol implementation in Asterisk Open Source 1.0.x, 1.2.x before 1.2.30, and 1.4.x before 1.4.21.2; Business Edition A.x.x, B.x.x before B.2.5.4, and C.x.x before C.1.10.3; AsteriskNOW; Appliance Developer Kit 0.x.x; and s800i 1.0.x before 1.2.0.1 allows remote attackers to cause a denial of service (call-number exhaustion and CPU consumption) by quickly sending a large number of IAX2 (IAX) POKE requests.
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Analysis
by VulDB Data Team • 12/30/2024
The vulnerability described in CVE-2008-3263 represents a significant denial of service weakness within the IAX2 protocol implementation of various Asterisk versions. This issue affects multiple product lines including the open source Asterisk 1.0.x, 1.2.x, and 1.4.x series, along with commercial editions and specialized appliances. The vulnerability stems from insufficient input validation and resource management within the IAX2 protocol handler, specifically in how it processes POKE requests which are part of the IAX2 signaling mechanism used for call setup and management. The flaw allows attackers to exploit the protocol implementation by flooding the system with rapid sequences of POKE requests, creating a cascading effect that consumes excessive system resources.
The technical exploitation of this vulnerability involves sending a high volume of IAX2 POKE requests in quick succession, which triggers a resource exhaustion condition within the Asterisk server. These POKE requests are legitimate protocol messages used for call signaling and registration purposes, but when sent in massive quantities without proper rate limiting or resource constraints, they cause the system to allocate memory and processing cycles inefficiently. The attack essentially creates a scenario where the server becomes overwhelmed with processing these requests, leading to call number exhaustion and sustained high CPU utilization. This behavior aligns with CWE-400 vulnerability classification for unchecked resource consumption and represents a classic denial of service attack vector.
The operational impact of this vulnerability extends beyond simple service disruption, as it can effectively render telephony systems unusable for legitimate callers while consuming significant computational resources. Network administrators and security teams face the challenge of maintaining service availability when attackers can easily exploit this weakness to cause system instability. The vulnerability particularly affects organizations relying on Asterisk for voice over IP communications, as it can be exploited from remote locations without requiring authentication or advanced privileges. The attack can be executed with minimal technical expertise, making it a popular choice for malicious actors seeking to disrupt telephony services.
Mitigation strategies for this vulnerability require implementing several layers of protection including rate limiting mechanisms, connection throttling, and proper resource allocation controls within the IAX2 protocol implementation. Organizations should upgrade to patched versions of Asterisk that address the resource exhaustion issues, with specific attention to versions 1.2.30, 1.4.21.2, and their corresponding commercial editions. Network-level protections such as firewall rules and intrusion detection systems can help identify and block suspicious traffic patterns, while system-level monitoring should track CPU utilization and connection counts to detect anomalous behavior. From an ATT&CK framework perspective, this vulnerability maps to T1499.004 for network denial of service and represents a technique that leverages protocol implementation weaknesses to achieve system compromise. The recommended remediation includes applying official security patches, implementing proper access controls, and establishing monitoring protocols to detect and respond to similar resource exhaustion attacks.