CVE-2006-5444 in Asterisk
Summary
by MITRE
Integer overflow in the get_input function in the Skinny channel driver (chan_skinny.c) in Asterisk 1.0.x before 1.0.12 and 1.2.x before 1.2.13, as used by Cisco SCCP phones, allows remote attackers to execute arbitrary code via a certain dlen value that passes a signed integer comparison and leads to a heap-based buffer overflow.
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Analysis
by VulDB Data Team • 04/25/2026
The vulnerability identified as CVE-2006-5444 represents a critical integer overflow flaw within the Skinny channel driver implementation of the Asterisk telephony software ecosystem. This issue specifically affects versions 1.0.x prior to 1.0.12 and 1.2.x prior to 1.2.13, making it particularly concerning for organizations utilizing Cisco SCCP phones that rely on Asterisk as their underlying communication platform. The vulnerability resides in the get_input function within the chan_skinny.c source file, which serves as the primary interface for handling Skinny Client Control Protocol communications between Cisco IP phones and the Asterisk server. The flaw manifests when processing incoming dlen values that trigger a signed integer comparison, ultimately resulting in a heap-based buffer overflow condition that can be exploited by remote attackers.
The technical exploitation of this vulnerability occurs through a carefully crafted dlen parameter that bypasses normal integer validation mechanisms within the Skinny channel driver. When the get_input function processes this malformed value, it fails to properly validate the input size, leading to an integer overflow that subsequently causes a heap buffer overflow. This type of vulnerability falls under CWE-190, which specifically addresses integer overflow conditions, and represents a classic example of how improper input validation can lead to memory corruption issues. The heap-based nature of the overflow means that attackers can manipulate heap memory structures to achieve arbitrary code execution, potentially gaining complete control over the affected Asterisk server. The vulnerability is particularly dangerous because it allows remote code execution without requiring authentication, making it an attractive target for attackers seeking to compromise telephony infrastructure.
The operational impact of CVE-2006-5444 extends far beyond simple service disruption, as it provides attackers with the capability to completely compromise the underlying Asterisk server infrastructure. Organizations relying on Cisco SCCP phones for their communication needs face significant risks including unauthorized access to phone systems, potential data exfiltration from telephony logs and configurations, and the ability to intercept or manipulate voice communications. The vulnerability's remote exploitability means that attackers can target these systems from outside the organization's network perimeter, making traditional network security measures insufficient for protection. This type of attack aligns with ATT&CK technique T1059.007 for command and control communications and T1566 for credential harvesting through social engineering, as compromised telephony systems can serve as entry points for broader network infiltration. The vulnerability affects organizations across various sectors including healthcare, finance, and government entities that depend on secure communication infrastructure.
Mitigation strategies for CVE-2006-5444 should prioritize immediate patching of affected Asterisk installations to versions 1.0.12 or 1.2.13 and later, which contain the necessary fixes for the integer overflow condition. Network segmentation should be implemented to isolate telephony infrastructure from general network access, reducing the attack surface for remote exploitation attempts. Additional defensive measures include implementing strict input validation on all telephony communication protocols, monitoring for anomalous dlen parameter values, and deploying intrusion detection systems specifically configured to detect Skinny protocol anomalies. Organizations should also consider disabling unnecessary Skinny protocol features and implementing network access controls that restrict which devices can communicate with the Asterisk server. The fix addresses the root cause by ensuring proper integer overflow detection and handling within the get_input function, preventing the heap buffer overflow condition that enables arbitrary code execution. Security monitoring should include regular vulnerability assessments targeting telephony infrastructure, as similar integer overflow patterns may exist in other components of the Asterisk codebase or related telephony applications.