CVE-2019-3938 in AM-100
Summary
by MITRE
Crestron AM-100 with firmware 1.6.0.2 and AM-101 with firmware 2.7.0.2 stores usernames, passwords, and other configuration options in the file generated via the "export configuration" feature. The configuration file is encrypted using the awenc binary. The same binary can be used to decrypt any configuration file since all the encryption logic is hard coded. A local attacker can use this vulnerability to gain access to devices username and passwords.
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Analysis
by VulDB Data Team • 09/11/2023
The vulnerability described in CVE-2019-3938 represents a critical security flaw in Crestron AM-100 and AM-101 devices that affects their configuration export functionality. This issue stems from improper implementation of encryption mechanisms within the device firmware, specifically version 1.6.0.2 for AM-100 and 2.7.0.2 for AM-101. The root cause lies in the use of the awenc binary which handles encryption for configuration files, but contains hardcoded encryption logic that can be easily reverse-engineered and reused by malicious actors. The flaw allows for the exposure of sensitive authentication credentials and system configuration data through what should be a secure export mechanism.
The technical implementation of this vulnerability demonstrates a fundamental weakness in the device's cryptographic approach where the encryption algorithm is not properly randomized or secured. The awenc binary serves as both the encryption and decryption mechanism, meaning that any attacker with access to the binary can readily decrypt any exported configuration file. This represents a classic case of weak cryptographic implementation where the same encryption keys or logic are hardcoded throughout the system, violating security best practices for credential storage and configuration management. The vulnerability directly maps to CWE-327, which addresses the use of weak or broken cryptographic algorithms, and specifically relates to CWE-312, concerning the exposure of sensitive information through cleartext storage.
From an operational perspective, this vulnerability creates significant risk for organizations relying on Crestron AM-100 and AM-101 devices for their automation and control systems. Local attackers who gain access to the device or its associated systems can exploit this flaw to extract usernames and passwords that provide unauthorized access to the devices themselves and potentially to integrated systems. The impact extends beyond individual device compromise to potentially enable broader network infiltration, as these credentials could be used to access other systems within the organization's infrastructure. This vulnerability aligns with ATT&CK technique T1566, which covers credential harvesting through various methods, and T1078, which addresses legitimate credentials usage. The exposure of configuration data also provides attackers with valuable system information that can be used for further targeting and exploitation.
Organizations affected by this vulnerability should immediately implement mitigation strategies focusing on network segmentation and access controls to limit local access to these devices. The most effective immediate remediation involves upgrading to firmware versions that address the hardcoded encryption issue, though this may not be immediately available. Administrators should also consider disabling the export configuration feature when not actively required, implementing stronger local access controls, and monitoring for unauthorized access attempts. The vulnerability highlights the importance of proper cryptographic implementation in embedded systems and serves as a reminder of the critical need for secure credential handling in IoT and industrial control systems. Additionally, organizations should conduct thorough inventory assessments to identify all affected devices and implement network monitoring to detect potential exploitation attempts.