Good Enough Emulation: Fuzzing a Modbus Thread for Bugs
🔍 This post details emulation-based analysis of the Socomec DIRIS M-70 gateway, where JTAG flash readout protection prevented full hardware debugging. The researcher emulated the Modbus processing thread with Unicorn, integrated AFL for coverage-guided fuzzing across hundreds of message types, and later adopted Qiling for built-in coverage and debugging. The effort uncovered multiple denial-of-service vulnerabilities and six CVEs, showing that a 'good enough' single-thread emulation approach can produce high-impact results.
