CVE-2007-3763 in Asterisk
Summary
by MITRE
The IAX2 channel driver (chan_iax2) 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 crafted (1) LAGRQ or (2) LAGRP frame that contains information elements of IAX frames, which results in a NULL pointer dereference when Asterisk does not properly set an associated variable.
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Analysis
by VulDB Data Team • 01/20/2025
The vulnerability identified as CVE-2007-3763 represents a critical denial of service flaw within the IAX2 channel driver component of Asterisk telecommunications software. This issue affects multiple versions of the Asterisk PBX system including the 1.2.x series before 1.2.22, 1.4.x series 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. The vulnerability specifically targets the IAX2 protocol implementation which is used for voice communication over IP networks. The flaw manifests when the system receives specially crafted LAGRQ or LAGRP frames that contain malformed information elements within IAX frames.
The technical root cause of this vulnerability lies in improper input validation and memory management within the IAX2 channel driver. When Asterisk processes these maliciously crafted frames, it fails to properly initialize or set an associated variable that should contain critical frame information. This leads to a NULL pointer dereference condition where the software attempts to access memory locations that have not been properly allocated or initialized. The vulnerability operates at the protocol level within the IAX2 implementation, specifically affecting how the system handles link quality requests and responses during the IAX2 signaling process. According to CWE standards, this corresponds to CWE-476 which describes NULL Pointer Dereference, a common class of software vulnerabilities that occurs when a program attempts to access memory through a pointer that has not been properly initialized.
The operational impact of this vulnerability is severe as it allows remote attackers to perform denial of service attacks against Asterisk systems without requiring authentication or prior access to the network. An attacker can simply send a specially crafted LAGRQ or LAGRP frame to any system running vulnerable versions of Asterisk, causing the application to crash and restart. This disruption affects the availability of voice services, potentially impacting business communications, emergency services, or any organization relying on Asterisk for telephony infrastructure. The vulnerability is particularly dangerous because it can be exploited from anywhere on the internet, making it a significant risk for organizations with publicly accessible Asterisk servers. The attack requires minimal skill and resources, as the malicious frames can be generated using standard network tools, making this vulnerability attractive to threat actors seeking to disrupt services.
Organizations should implement immediate mitigations to protect against this vulnerability. The primary solution involves upgrading to patched versions of Asterisk software, specifically versions 1.2.22 or later for the 1.2.x series, and 1.4.8 or later for the 1.4.x series. System administrators should also consider implementing network-level filtering to block IAX2 traffic at firewalls or network access control devices, particularly when such services are not required for business operations. Additionally, monitoring systems should be configured to detect unusual patterns of IAX2 traffic that might indicate exploitation attempts. From an ATT&CK framework perspective, this vulnerability aligns with techniques involving service stoppage and denial of service, specifically mapping to T1499.004 for Network Denial of Service and T1499.001 for Network Denial of Service. Organizations should also consider implementing intrusion detection systems that can identify and alert on malformed IAX2 frames, as this vulnerability could potentially be leveraged as part of broader attack campaigns targeting telephony infrastructure.