CVE-2009-2346 in Asterisk
Summary
by MITRE
The IAX2 protocol implementation in Asterisk Open Source 1.2.x before 1.2.35, 1.4.x before 1.4.26.2, 1.6.0.x before 1.6.0.15, and 1.6.1.x before 1.6.1.6; Business Edition B.x.x before B.2.5.10, C.2.x before C.2.4.3, and C.3.x before C.3.1.1; and s800i 1.3.x before 1.3.0.3 allows remote attackers to cause a denial of service (call-number exhaustion) by initiating many IAX2 message exchanges, a related issue to CVE-2008-3263.
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Analysis
by VulDB Data Team • 04/06/2025
The vulnerability described in CVE-2009-2346 represents a significant denial of service weakness within the IAX2 protocol implementation of Asterisk Open Source and related telephony systems. This flaw affects multiple versions of the Asterisk telephony platform including various 1.2.x, 1.4.x, 1.6.0.x, and 1.6.1.x releases, as well as specific Business Edition and s800i versions. The vulnerability specifically targets the IAX2 (Inter-Asterisk eXchange version 2) protocol which is used for communication between Asterisk servers and clients, making it a critical component for VoIP infrastructure. The issue is categorized under CWE-400 which specifically addresses "Uncontrolled Resource Consumption" or "Resource Exhaustion" vulnerabilities that can lead to system unavailability.
The technical exploitation of this vulnerability occurs through a process known as call-number exhaustion, where remote attackers can initiate numerous IAX2 message exchanges that consume system resources without proper rate limiting or resource management. This particular flaw is closely related to CVE-2008-3263, indicating a pattern of resource consumption issues within the IAX2 protocol implementation. Attackers can leverage this weakness by creating multiple simultaneous IAX2 connections or message sequences that gradually deplete available call slots or system resources, ultimately rendering the affected telephony system unable to process legitimate calls. The vulnerability operates at the protocol level, making it particularly dangerous as it can be exploited without requiring authentication or elevated privileges, and can be executed from any remote location with network access to the target system.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise entire telephony infrastructures within organizations that rely on Asterisk for their communication systems. When exploited successfully, the vulnerability can cause cascading failures in business communication networks, affecting customer service operations, emergency response systems, and internal communications. The resource exhaustion can lead to complete system crashes or severe performance degradation that may take considerable time to recover from, potentially resulting in significant business disruption and financial losses. Organizations using affected versions of Asterisk are particularly vulnerable since the flaw exists in widely deployed telephony software used across various industries including healthcare, financial services, and telecommunications.
Mitigation strategies for this vulnerability involve immediate software updates to patched versions of the Asterisk platform, which address the resource management issues in the IAX2 protocol implementation. System administrators should implement network-level rate limiting and connection throttling mechanisms to prevent excessive IAX2 message exchanges from overwhelming the system. Additionally, monitoring systems should be configured to detect unusual patterns of IAX2 traffic that may indicate exploitation attempts. The implementation of proper access controls and firewall rules can help limit exposure to this vulnerability by restricting access to IAX2 ports and services. Organizations should also consider implementing intrusion detection systems that can identify and alert on suspicious IAX2 protocol behavior. This vulnerability aligns with ATT&CK technique T1499 which covers network denial of service attacks and demonstrates how protocol-level weaknesses can be exploited to achieve system unavailability, making it a critical concern for security teams managing telephony infrastructure.