CVE-2006-2923 in LoudHush
Summary
by MITRE
The iax_net_read function in the iaxclient open source library, as used in multiple products including (a) LoudHush 1.3.6, (b) IDE FISK 1.35 and earlier, (c) Kiax 0.8.5 and earlier, (d) DIAX, (e) Ziaxphone, (f) IAX Phone, (g) X-lite, (h) MediaX, (i) Extreme Networks ePhone, and (j) iaxComm before 1.2.0, allows remote attackers to execute arbitrary code via crafted IAX 2 (IAX2) packets with truncated (1) full frames or (2) mini-frames, which are detected in a length check but still processed, leading to buffer overflows related to negative length values.
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Analysis
by VulDB Data Team • 06/21/2019
The vulnerability identified as CVE-2006-2923 represents a critical buffer overflow condition within the iax_net_read function of the iaxclient open source library, which serves as a foundational component for numerous voice over internet protocol applications. This flaw manifests in multiple commercial and open source products including LoudHush, IDE FISK, Kiax, DIAX, Ziaxphone, IAX Phone, X-lite, MediaX, Extreme Networks ePhone, and iaxComm versions prior to 1.2.0. The vulnerability stems from improper handling of IAX2 packet structures where crafted malicious packets can exploit the protocol's length validation mechanism. The iaxclient library implements a length check mechanism to detect malformed packets, but this validation fails to properly account for negative length values that can occur when packets are truncated during transmission. This design flaw creates a scenario where packets that would normally be rejected due to length inconsistencies are still processed by the vulnerable code path, resulting in memory corruption.
The technical exploitation of this vulnerability occurs through the manipulation of IAX2 protocol frames, specifically targeting both full frames and mini-frames that have been truncated to create negative length values. When the iax_net_read function processes these malformed packets, it interprets the negative length values as valid frame sizes, causing the application to allocate insufficient memory or access invalid memory regions. This behavior directly maps to CWE-121, which describes heap-based buffer overflow conditions, and CWE-125, which covers out-of-bounds read vulnerabilities. The vulnerability operates at the network protocol layer, making it particularly dangerous as it can be triggered remotely without requiring any authentication or local access. The specific nature of the flaw allows attackers to craft packets that bypass initial validation checks while still triggering the buffer overflow condition, making detection and prevention significantly more challenging.
The operational impact of this vulnerability extends across numerous voice communication platforms and enterprise telephony solutions, potentially affecting organizations that rely on IAX2 protocol implementations for their communication infrastructure. Remote code execution capabilities mean that attackers can gain complete control over affected systems, potentially leading to unauthorized access to communication networks, data exfiltration, or service disruption. The widespread adoption of the iaxclient library across multiple vendors and products amplifies the potential impact, as a single vulnerability can affect dozens of different applications and devices. This vulnerability directly aligns with ATT&CK technique T1203, which describes exploiting weaknesses in network protocols to gain unauthorized access, and T1059, which covers command and control through remote code execution. Organizations using affected software may experience complete system compromise, with attackers potentially establishing persistent backdoors or using the compromised systems as launch points for further network infiltration.
Mitigation strategies for this vulnerability require immediate patching of affected software versions to address the buffer overflow condition in the iax_net_read function. System administrators should prioritize updating all instances of the vulnerable iaxclient library to versions that properly handle negative length values in IAX2 packet processing. Network segmentation and firewall rules can be implemented to restrict IAX2 protocol traffic where possible, reducing the attack surface. Additionally, implementing network monitoring solutions that can detect malformed IAX2 packets may help identify exploitation attempts. The vulnerability highlights the importance of proper input validation and memory management in network protocol implementations, particularly when dealing with variable-length packet structures. Organizations should conduct comprehensive vulnerability assessments to identify all instances of the affected library across their network infrastructure, including legacy systems that may not receive regular updates. Security teams should also implement intrusion detection systems specifically tuned to identify patterns consistent with IAX2 protocol exploitation attempts, as the vulnerability's nature makes it particularly suitable for automated exploitation tools.