CVE-2019-5137 in AWK-3131A
Summary
by MITRE
The usage of hard-coded cryptographic keys within the ServiceAgent binary allows for the decryption of captured traffic across the network from or to the Moxa AWK-3131A firmware version 1.13.
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Analysis
by VulDB Data Team • 04/02/2024
The vulnerability identified as CVE-2019-5137 represents a critical cryptographic weakness in the Moxa AWK-3131A industrial network device firmware version 1.13. This issue stems from the inclusion of hard-coded cryptographic keys within the ServiceAgent binary component of the device software. The presence of such static keys fundamentally undermines the security posture of the network communications, as these keys remain unchanged across all device instances and deployments. The ServiceAgent binary serves as a critical communication module responsible for handling network traffic between the device and external systems, making it a prime target for attackers seeking to intercept and decrypt sensitive data flows.
The technical flaw manifests through the improper implementation of cryptographic security measures where developers embedded fixed encryption keys directly into the binary code rather than generating unique keys for each device instance or utilizing proper key management protocols. This design choice violates fundamental security principles outlined in cwe-327 and cwe-320, which specifically address the use of weak cryptography and the exposure of cryptographic keys. The hard-coded nature of these keys means that once an attacker gains access to the firmware or can observe network traffic, they can easily reverse-engineer the cryptographic components and decrypt communications that should remain confidential. This vulnerability operates at the application layer and affects the confidentiality aspect of the CIA triad, as it directly enables unauthorized decryption of network traffic without requiring additional authentication or complex attack vectors.
The operational impact of CVE-2019-5137 extends beyond simple data interception to encompass potential system compromise and operational disruption in industrial environments. Network traffic captured from or to the affected Moxa AWK-3131A devices can be decrypted in real-time, exposing sensitive operational data including configuration parameters, user credentials, system status information, and potentially control commands that could affect industrial processes. This vulnerability particularly impacts environments where industrial control systems (ICS) and industrial internet of things (IIoT) devices operate in close proximity to corporate networks, as it provides attackers with a straightforward method to gain insights into network communications and potentially escalate their attacks. The vulnerability's impact is amplified in environments following the attack pattern described in the attack technique 1071 which involves the use of network sniffing and decryption to gain intelligence about networked systems.
Mitigation strategies for CVE-2019-5137 require immediate action to address the root cause of the hard-coded keys. Organizations should implement network segmentation to isolate affected devices from critical systems and establish monitoring protocols to detect unusual network traffic patterns that might indicate decryption activities. The most effective long-term solution involves updating the firmware to a version that properly implements dynamic key generation or key rotation mechanisms, ensuring that each device instance uses unique cryptographic keys. Security professionals should also consider implementing additional network-layer encryption using protocols such as ipsec or tls to provide defense-in-depth against potential exploitation of this vulnerability. The remediation process should align with industry best practices for embedded system security and follow guidelines established by nist 800-53 and other cybersecurity frameworks that emphasize proper key management and cryptographic implementation. Organizations should also conduct comprehensive vulnerability assessments to identify other devices that might contain similar hard-coded cryptographic implementations, as this represents a common pattern in industrial device firmware development that can lead to widespread security exposure across networked industrial systems.