CVE-2016-5639 in AirMedia AM-100
Summary
by MITRE
Directory traversal vulnerability in cgi-bin/login.cgi on Crestron AirMedia AM-100 devices with firmware before 1.4.0.13 allows remote attackers to read arbitrary files via a .. (dot dot) in the src parameter.
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Analysis
by VulDB Data Team • 12/05/2024
The CVE-2016-5639 vulnerability represents a critical directory traversal flaw in the Crestron AirMedia AM-100 device firmware, specifically affecting versions prior to 1.4.0.13. This vulnerability exists within the cgi-bin/login.cgi script which handles authentication requests for the device's web interface. The flaw stems from inadequate input validation of the src parameter, allowing remote attackers to manipulate file paths through the use of directory traversal sequences. The vulnerability is classified as CWE-22, which specifically addresses improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal attacks. These types of vulnerabilities are particularly dangerous in networked devices as they can provide unauthorized access to sensitive system files and data.
The technical exploitation of this vulnerability occurs when an attacker submits a malicious src parameter containing .. (dot dot) sequences to the login.cgi script. This allows the attacker to navigate outside of the intended directory structure and access arbitrary files on the device's file system. The impact extends beyond simple file reading capabilities as attackers can potentially access configuration files, authentication credentials, system logs, and other sensitive data stored within the device's file system. The vulnerability demonstrates a classic lack of proper input sanitization and validation, where user-supplied parameters are directly incorporated into file access operations without adequate security checks. This type of flaw is particularly concerning in IoT and networked multimedia devices where the web interface serves as the primary management entry point.
The operational impact of CVE-2016-5639 is significant for organizations utilizing Crestron AirMedia AM-100 devices in their network infrastructure. Remote attackers can exploit this vulnerability to gain unauthorized access to device configurations, potentially leading to complete device compromise and subsequent network infiltration. The vulnerability enables attackers to read sensitive system information that could be used for further attacks, including privilege escalation attempts or the discovery of other network devices. From an adversarial perspective, this vulnerability aligns with ATT&CK technique T1083 (File and Directory Discovery) and T1566 (Phishing for Information), as attackers can systematically enumerate and extract valuable data from the compromised device. The remote nature of the attack means that threat actors do not require physical access to the device, making it particularly attractive for cybercriminals seeking to exploit networked multimedia equipment.
Mitigation strategies for this vulnerability require immediate firmware updates to version 1.4.0.13 or later, which address the directory traversal flaw through proper input validation and sanitization. Organizations should also implement network segmentation to limit access to these devices, ensuring they are not directly exposed to untrusted networks. Additional security measures include disabling unnecessary web services, implementing strong access controls, and monitoring for suspicious file access patterns. The vulnerability highlights the importance of regular firmware updates and security assessments for networked devices, particularly those handling authentication and access control functions. Security professionals should also consider implementing network intrusion detection systems that can identify and alert on suspicious parameter sequences attempting directory traversal attacks. This vulnerability serves as a reminder of the critical importance of input validation in web applications and the potential consequences of inadequate security controls in embedded systems.