The most likely explanation is that they generated the weak key externally, imported it into the HSM, generated the CSR from it, and finally had Root CA sign it.

A FIPS HSM does not forbid one to import keys into it.

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cstdr 2 hours ago | parent [-]

But shouldn't such a HSM support key attestation (and the parent require such attestation)? Attestation would also track whether a key was imported or generated on the HSM, and of sufficient length.

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zimmerfrei an hour ago | parent [-]

Attestation is not required by the compliance standard for browser CAs (WebTrust) and it is also quite vendor-specific and not very interoperable, so it is not commonly done.

The Root CA must sign requests after authentication, but a "manual" approval is also accepted if done with the appropriate oversight with witnesses (clearly not the case here).

	▲	cstdr an hour ago \| parent [-]
		Of course it's not required, as we see here. The question is why not? Getting a simple code-signing cert seems to have more stringent requirements in that it either requires attestation or CA-issued hardware.