I liked the idea conceptually of CAA record only allowing DNS validation. Then use DNSSEC.
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.
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.