RPKI unknown for superprefixes of existing ROA ?

Sun Oct 22 16:17:42 UTC 2023

On Sun, Oct 22, 2023 at 5:47 PM Job Snijders via NANOG <nanog at nanog.org> wrote:
>
> On Sun, 22 Oct 2023 at 17:42, Amir Herzberg <amir.lists at gmail.com> wrote:
>>
>> Bill, thanks! You explained the issue much better than me. Yes, the problem is that, in my example, the operator was allocated  1.2.4/22 but the attacker is announcing  1.2.0/20, which is larger than the allocation, so the operator cannot issue ROA for it (or covering it). Of course, the RIR _could_ do it (but I don't think they do, right?). So this `superprefix hijack' may succeed in spite of all the ROAs that the operator could publish.
>>
>> I'm not saying this is much of a concern, as I never heard of such attacks in the wild, but I guess it _could_ happen in the future.
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>
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> How is “success” measured here?
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> The attacker won’t be drawing traffic towards itself destined for addresses in the /22, because of LPM
> https://en.wikipedia.org/wiki/Longest_prefix_match
>
> Attackers don’t hijack IP traffic by announcing less-specifics. It don’t work that way.

Even for positive ROAs (not AS 0 ROAs), that depends on how much of a
region's routers have full-routes or use partial routes.
In Brazil there are still many Mikrotik devices being used by
BGP-speaking networks that fumble on full-routes, and the offending
announcement might not have a LPM to choose from.

That might be yet more prevalent in routers connecting to IXPs,
because even default-route networks would see those announcements
without a LPM to follow.

Rubens