Re:Intel x86 documentation has more pages than the 6502 has ...
by rasz_pl on Thursday December 08, 2016 @09:08AM
(#13130328)
> if software backdoors were available and leaked to the public
https://www.blackhat.com/us-15/briefings.html#the-memory-sin...
conveniently "discovered" by a 3 letter agency favorite principle contractor (Batelle Memorial Institute - have fun researching them) employee just after everybody switched to the next(fixed) cpu generation.
Re:Intel x86 documentation has more pages than the 6502 has ...
by qb45 on Thursday December 08, 2016 @11:04AM
(#13131180)
I doubt that this can be used for VM escape because it requires access to the physical LAPIC and afaik hypervisors wouldn't allow VMs to touch this.
It also doesn't work from userspace so pretty much all you can do with it is hacking SMM from a kernel running on the bare metal. Maybe useful for rootkits, but truth be told 3LAs seem to have no problem making non-SMM malware undetectable by commercial AVs. See stuxnet :)
> conveniently "discovered" by a 3 letter agency favorite principle contractor
Not sure what you are alluding to. 3LAs wouldn't want this to be known if it was their job, methinks.
Re:Intel x86 documentation has more pages than the 6502 has ...
by redblacktree on Thursday December 08, 2016 @11:16AM
(#13131302)
I think he's saying that the 3LAs knew about it for a long time, but publicly "discovered" the flaw when it was no longer useful to them (after everyone had upgraded)
There certainly are undocumented debug facilities in modern CPUs. For one example, the leaked Socket AM3 datasheet clearly shows a JTAG interface, though I don't know if it's operational in production silicon.
Hopefully, debug capabilities cannot be used to pwn the CPU from unprivileged code without external debug hardware which could pwn the CPU anyway by itself. It's not even clear if they are enabled in production chips at all.
LOADALL for example worked only in RING0 and got ultimately removed early in the 486 days so it seems Intel cared about security somewhat (and probably also about future compatibility, to be honest, it's not fun when software relies on features you want to change in the next generation).
Nowadays they should care even more - if software backdoors were available and leaked to the public, the magnitude of shit happening in all those cloud companies would be monumental.