Delta Plc The Password Function Is Ineffective Guide

As industrial control systems (ICS) adopt greater connectivity, the security of programmable logic controllers (PLCs) becomes paramount. Delta Electronics PLCs, widely used in automation, offer a built-in password protection function intended to prevent unauthorized access to logic and configuration. This paper critically evaluates the effectiveness of this function. Through a combination of vendor documentation analysis, reverse engineering of communication protocols (specifically Delta’s proprietary RS-485/Modbus variants and Ethernet commands), and practical attack modeling, we demonstrate that the password mechanism is fundamentally ineffective. It provides only a false sense of security, vulnerable to both trivial interception attacks and offline brute-force/cryptanalysis. We conclude that the function serves as an access hurdle rather than a true security boundary, recommending its deprecation in favor of modern, standards-based authentication.

| Security Requirement | Delta PLC Implementation | Verdict | |----------------------|--------------------------|---------| | (Are you who you claim to be?) | Passes credential over wire in cleartext or weak obfuscation | Failed | | Authorization (Can you perform this action?) | No role separation; password unlocks full read/write | Failed | | Accounting (What did you do?) | No logging of failed/successful attempts | Failed | delta plc the password function is ineffective

Furthermore, the function violates Kerckhoffs’s principle: the security depends on the secrecy of the protocol implementation, not on a strong cryptographic key. Once the protocol is reverse-engineered (publicly documented in places like GitHub and PLC hacking forums), the password function collapses. | Security Requirement | Delta PLC Implementation |

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We set up a test environment: a Delta DVP-14SS2 PLC (RS-232/RS-485) and a Delta AS228T (Ethernet). A password was set using ISPSoft. “Reverse Engineering Delta PLC Communication Protocol

[1] Delta Electronics, DVP-PLC User Manual (Programming) , 2019. [2] K. Stouffer, et al., Guide to Industrial Control Systems (ICS) Security , NIST SP 800-82 Rev. 2. [3] J. M. Moura, “Reverse Engineering Delta PLC Communication Protocol,” DEFCON 27 ICS Village , 2019. [4] IEC 62443-4-2: Security for IACS components.