Re:Undocumented x86 instructions to control the CPU at the m...
by Chilinot on Wednesday July 07, 2021 @04:13PM
(#27765287)
Interesting, the conclusion only speculates that this can have security consequences. Anyone with better understanding that could provide an example of what would be possible to do using these instructions?
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Re:Undocumented x86 instructions to control the CPU at the m...
by d3k on Wednesday July 07, 2021 @04:42PM
(#27765535)
It should be possible to see if a given "secure" binary makes use of a given microcode instruction. If that is the case, it could be possible to use udbgrd/udbgwr to modify the microcode instruction to do something else, e.g. to store some register data in the URAM or the SRAM. By doing this you should be able to "spy" the data the "secure" binary is processing.
Re:Undocumented x86 instructions to control the CPU at the m...
by dmitrygr on Wednesday July 07, 2021 @04:41PM
(#27765524)
anything! if you can get them to execute. the authors found one way to enable them, but others may exist (we do not know). maybe another secret instruction enables these also. we do not know.
Re:Undocumented x86 instructions to control the CPU at the m...
by TeeMassive on Wednesday July 07, 2021 @05:44PM
(#27766069)