CVE-2008-3264 in Asterisk
Summary
by MITRE
The FWDOWNL firmware-download 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 (traffic amplification) via an IAX2 FWDOWNL request.
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Analysis
by VulDB Data Team • 04/14/2025
The vulnerability described in CVE-2008-3264 represents a significant security flaw within the IAX2 protocol implementation of various Asterisk versions, specifically affecting firmware download functionality. This issue manifests through the FWDOWNL command within the IAX2 protocol which enables remote attackers to exploit a traffic amplification mechanism. The vulnerability impacts a wide range of Asterisk implementations including open source versions 1.0.x through 1.4.x, business editions A.x.x through C.x.x, AsteriskNOW distributions, appliance developer kits, and s800i systems. The flaw exists in the firmware download implementation where the system fails to properly validate incoming FWDOWNL requests, creating an opportunity for malicious actors to leverage the protocol's design for amplification attacks.
The technical mechanism behind this vulnerability stems from the improper handling of IAX2 FWDOWNL requests which allows attackers to send malformed or specially crafted packets that trigger excessive network traffic generation. When the affected Asterisk systems process these requests, they respond with amplified traffic that can overwhelm network resources and cause legitimate service disruption. This traffic amplification occurs because the system generates responses that are significantly larger than the original request, creating a multiplier effect that can be exploited to exhaust network bandwidth or system resources. The vulnerability is classified under CWE-400 as an Uncontrolled Resource Consumption issue, specifically related to insufficient input validation and improper response handling within network protocols.
The operational impact of this vulnerability extends beyond simple denial of service conditions, as it enables attackers to leverage the Asterisk infrastructure for large-scale traffic disruption campaigns. The amplification factor can range from several times to orders of magnitude larger than the original attack payload, making it particularly dangerous in network environments where bandwidth is limited or where the target system serves as a network hub. Attackers can exploit this vulnerability without requiring authentication or specific privileges, making it an attractive vector for malicious actors seeking to disrupt communications services. The widespread nature of affected systems means that organizations using any of the listed Asterisk versions are potentially exposed to this threat, particularly those operating VoIP infrastructure or telephony systems that rely on IAX2 protocol implementations.
Mitigation strategies for this vulnerability require immediate implementation of network-level protections and protocol-specific restrictions. Organizations should implement rate limiting on IAX2 traffic to prevent excessive request processing, disable unnecessary firmware download functionality when not required, and apply the relevant security patches released by the Asterisk community. Network administrators should monitor for unusual traffic patterns that might indicate exploitation attempts, particularly around IAX2 port 4569 traffic. The implementation of firewall rules to restrict access to IAX2 endpoints and the use of intrusion detection systems can help identify and block malicious FWDOWNL requests. Additionally, organizations should consider implementing protocol-level validation controls that verify the legitimacy of firmware download requests before processing them, as specified in the ATT&CK framework's network denial of service techniques. Regular security assessments of telephony infrastructure and maintaining updated software versions are essential preventive measures that address both this specific vulnerability and similar protocol-level weaknesses.