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314 points Bogdanp | 1 comments | | HN request time: 0.434s | source
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lq9AJ8yrfs ◴[] No.44380076[source]
So all the addressing bodies (e.g., ISPs and cloud providers) are on board then right? They sometimes cycle through IP's with great velocity. Faster than 6 days at least.

Lots of sport here, unless perhaps they cool off IPs before reallocating, or perhaps query and revoke any certs before reusing the IP?

If the addressing bodies are not on board then it's a user responsibility to validate the host header and reject unwanted IP address based connections until any legacy certs are gone / or revoke any legacy certs. Or just wait to use your shiny new IP?

I wonder how many IP certs you could get for how much money with the different cloud providers.

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gruez ◴[] No.44381336[source]
>So all the addressing bodies (e.g., ISPs and cloud providers) are on board then right? They sometimes cycle through IP's with great velocity. Faster than 6 days at least.

>Lots of sport here, unless perhaps they cool off IPs before reallocating, or perhaps query and revoke any certs before reusing the IP?

I don't see how this is any different than custom/vanity domains you can get from cloud providers. For instance on azure you can assign a DNS name to your VMs in the form of myapp.westus.cloudapp.azure.com, and CAs will happily issue certificates for it[1]. There's no cooloff for those domains either, so theoretically someone else can snatch the domain from you if your VM gets decommissioned.

[1] https://crt.sh/?identity=westus.cloudapp.azure.com&exclude=e...

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1. akerl_ ◴[] No.44383915[source]
The difference is the directionality.

The attack here isn't "snatch a domain from somebody who previously got a cert for it", it's "get an IP, get a cert issued, then release it and let somebody interesting pick it up".

In practice, this seems relatively low risk. You'd need to get a certificate for the IP, release it, have somebody else pick it up, have that person actually be doing something that is public-facing and also worth MITMing, then hijack either BGP or DNS to MITM traffic towards that IP. And you have ~6 days to do it. Plus if you can hijack your target's DNS or IPs... you can just skip the shenanigans and get a valid fresh cert for that target.