How “omnipotent” hackers tied to NSA hid for 14 years—and were found at last | Ars Technica: One of the Equation Group's malware platforms, for instance, rewrote the hard-drive firmware of infected computers—a never-before-seen engineering marvel that worked on 12 drive categories from manufacturers including Western Digital, Maxtor, Samsung, IBM, Micron, Toshiba, and Seagate.
The malicious firmware created a secret storage vault that survived military-grade disk wiping and reformatting, making sensitive data stolen from victims available even after reformatting the drive and reinstalling the operating system. The firmware also provided programming interfaces that other code in Equation Group's sprawling malware library could access. Once a hard drive was compromised, the infection was impossible to detect or remove.