LAS VEGAS — Some x86 CPUs have hidden backdoors that let you seize root by sending a command to an undocumented RISC core that manages the main CPU, security researcher Christopher Domas told the Black Hat conference here Thursday (Aug. 9). The command — ".byte 0x0f, 0x3f" in Linux — "isn't supposed to exist, doesn't have a name, and gives you root right away," Domas said, adding that he calls it
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