However, if you can MitM the uplinks at all of Let's Encrypt's perspectives, you can basically break the entire CA for everyone. Adding more perspectives reduces the risk of that.
> Domain Validated (DV) certificates are the least-identity-validated SSL certificates and can be obtained quickly and easily—even by a malicious bot. These certificates are low-cost certificates that only require validation that a company or person can demonstrate control over a web domain for which they want to secure a certificate.
This is arguably a flaw in allowing DV certs at all, but given that it's there, LE doing this raises the bar for spoofing about as far as it can be raised.
I think few independent site owners would go through the more costly and complicated EV process.
That's a policy, not an inherent consequence of DV certs.
If every verification method other than DNS was shut off, it would still be DV, but with care it could be immune to MitM. I'm not advocating for that, but it's an option.
I say “conceptually” since I know: 1. Actual attacks found with CT have used compromised TLDs, which kills the whole thing anyway, and 2. I haven’t really seen where the hosting company’s infrastructure (BGP ads and internal routing) is what’s compromised. Well certainly in the latter case they can probably also get in to the hosting machines directly.
The Use case - Lot of SAAS based products allow/require the administrators to prove the ownership of a domain via ACME methods. The administrators then are allowed to manage the profiles for users that have email address with same domains in the SAAS product.
Ironically the testing setup itself used the network hack for the successful ACME challenge