CVE-2018-5400 in DCU-210E RP-210E
Summary
by MITRE
The Auto-Maskin products utilize an undocumented custom protocol to set up Modbus communications with other devices without validating those devices. The originating device sends a message in plaintext, 48:65:6c:6c:6f:20:57:6f:72:6c:64, "Hello World" over UDP ports 44444-44446 to the broadcast address for the LAN. Without verification devices respond to any of these broadcast messages on the LAN with a plaintext reply over UDP containing the device model and firmware version. Following this exchange the devices allow Modbus transmissions between the two devices on the standard Modbus port 502 TCP. Impact: An attacker can exploit this vulnerability to send arbitrary messages to any DCU or RP device through spoofing or replay attacks as long as they have access to the network. Affected releases are Auto-Maskin DCU-210E RP-210E: Versions prior to 3.7 on ARMv7.
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Analysis
by VulDB Data Team • 02/01/2025
The CVE-2018-5400 vulnerability affects Auto-Maskin products that implement a custom protocol for establishing Modbus communications with other devices on a local area network. This vulnerability stems from the absence of device validation mechanisms during the initial communication setup phase, creating a fundamental security flaw that violates basic network security principles. The protocol relies on an undocumented custom approach that lacks proper authentication and authorization checks, making it susceptible to exploitation by unauthorized parties who can simply send messages to any device on the network without proper verification. The vulnerability specifically targets devices such as the DCU-210E and RP-210E models, with affected versions prior to 3.7 running on ARMv7 architecture.
The technical implementation of this vulnerability involves a plaintext communication pattern where the originating device broadcasts a message containing the string "Hello World" over UDP ports 44444-44446 to the local broadcast address. This broadcast mechanism operates without any form of device authentication or network access control, allowing any device on the network to respond to these messages. The response contains sensitive information including the device model and firmware version in plaintext format, providing attackers with detailed information about the targeted devices. This information disclosure aspect of the vulnerability aligns with CWE-200, which addresses improper handling of sensitive information, and represents a significant weakness in the device's security architecture.
The operational impact of this vulnerability extends far beyond simple information disclosure, as it enables attackers to perform spoofing and replay attacks against any DCU or RP device on the network. The lack of validation allows malicious actors to establish communication channels with target devices and subsequently send arbitrary Modbus messages through the established connection on the standard Modbus port 502 TCP. This creates a pathway for attackers to manipulate industrial control systems, potentially causing operational disruptions, data corruption, or even physical damage to equipment. The vulnerability operates at the network level and can be exploited from any location with network access, making it particularly dangerous in industrial environments where operational technology systems are critical to business operations.
This vulnerability represents a clear violation of the principle of least privilege and proper authentication mechanisms that should be implemented in industrial control systems. The attack pattern described aligns with techniques found in the MITRE ATT&CK framework under the 'Initial Access' and 'Command and Control' phases, where adversaries establish communication channels to target systems. The use of plaintext communication and lack of encryption directly violates security standards such as those outlined in NIST SP 800-82 for industrial control systems security. Organizations affected by this vulnerability should implement immediate network segmentation to isolate critical industrial control systems, deploy network monitoring solutions to detect unauthorized broadcast communications, and upgrade to supported firmware versions that address the authentication and validation flaws. The vulnerability demonstrates the critical importance of proper device authentication and the dangers of relying on undocumented protocols in security-sensitive environments.