This is perhaps outside even the vague bounds you were thinking of, but it probably wins the 'unusually prolific' prize by a gigabyte-mile. Behold, the hidden, secret and heinous X86 2-byte 'launch instruction' 0x0F, 0x3F. See this talk about the discovery: https://www.youtube.com/watch?v=jmTwlEh8L7g DEF CON 26 - Christopher Domas - GOD MODE UNLOCKED Hardware Backdoors in redacted x86 46:03 DEFCON Conference Oct 23, 2018 Complexity is increasing. Trust eroding. In the wake of Spectre and Meltdown, when it seems that things cannot get any darker for processor security, the last light goes out. This talk will demonstrate what everyone has long feared but never proven: there are hardware backdoors in some x86 processors, and they're buried deeper than we ever imagined possible. While this research specifically examines a third-party processor, we use this as a stepping stone to explore the feasibility of more widespread hardware backdoors. After which you will never trust your Intel-based PC, ever again. Guy