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Even aside from security vulnerabilities, wouldn't the ability to write your own microcode for Intel CPUs be interesting for many hobbyists?
by fouric 5y ago
Even aside from security vulnerabilities, wouldn't the ability to write your own microcode for Intel CPUs be interesting for many hobbyists?
- quotemstr 5y agoRight. Writing custom microcode can be useful for understanding fine details of the CPU's microarchitecture, which in turn is useful for things ranging from low-level optimization to discovering microarchitectural vulnerabilities that don't require custom microcode to exploit.
- yxhuvud 5y agoOr you can treat your Intel processor as a fpga and write instructions that do what you want them to. Unlocking features locked down to higher end machines is also not off the table. So it may or not be a security issue but it makes the machine hackable in a way it hasn't been before.
- rolph 5y agoshould you be capable enough to write your own microcode, there is an elevated chance that you could also encrypt and sign that code like intel microcode.
- marcan_42 5y agoNot unless you break RSA, which would be much more of an accomplishment than working out how microcode works.
- AnimalMuppet 5y agoFrom the article: > As a matter of fact, several vulnerabilities in Intel ME have been discovered in the past. Among others, Ermolov, Sklyarov, and Goryachy described a method to extract the secret key that is used inside the CPU to decrypt microcode updates, which also led to the possibility of executing your own microcode on the CPU or reading Intel's microcode. So you don't have to break RSA. You just have to use the private key to derive the public key, which I believe is do-able.
- spockz 5y agoEncryption and signing are two different things both using rsa keys. The public key used for encryption does not need to be part of the same key pair as the private key used for signing. Not sure whether this is the case here.
- SAI_Peregrinus 5y agoAlso they talk about a secret key, not a private key. That means it's likely using symmetric key encryption, with RSA for signing (and maybe to update the symmetric key a la RSA-KEM). This is normal, nobody does direct asymmetric message encryption.