HDD Firmware Hacking
The article details a deep dive into the firmware of a Western Digital hard drive (model WD40EFAX), where the researcher used a JTAG debugger to dump the firmware and analyze the code. They found that the drive's processor, an ARM Cortex-M0, runs a real-time operating system (RTOS) with a vulnerability in the command handler for vendor-specific SCSI commands. By sending a malformed command, an attacker can overwrite a function pointer, leading to arbitrary code execution. The exploit requires physical access or the ability to write raw sectors to the drive, but once executed, the malware can persist across OS reinstalls because it resides in the drive's firmware. The researcher demonstrated a proof-of-concept that modifies the drive's behavior to return corrupted data. The article was published on May 14, 2026, and includes detailed technical steps, such as using a Bus Pirate for JTAG communication and Ghidra for disassembly.
Hard drive firmware exploits can enable persistent, undetectable malware that survives OS reinstallation.