[arin-ppml] implementing RPKI prefix validation actually increases risk

Fernando Frediani fhfrediani at gmail.com
Mon Jun 5 22:45:12 EDT 2023

Hello Michael

If I am not forgotten you are someone who strongly opposed IPv6 sometime 
ago, called it a undue burden and seems to be fighting against it with 
all forces and stating clearly and you don't need it. Not surprised now 
by your email about  RPKI as well.


On 05/06/2023 23:29, Michel Py via ARIN-PPML wrote:
> Hi folks,
> I am bumping into a dark side of RPKI prefix validation that actually 
> increases risk to the network when deployed.
> As many others here do, I use BGP blackhole feeds (RTBH). This 
> technique has been around for a long time.
> It is quite a common situation in some orgs to have the in-house 
> SIEM/IDS redistribute blackhole prefixes via a BGP feed.
> Also, there are numerous publicly available ones such as :
> https://team-cymru.com/community-services/bogon-reference/bogon-reference-bgp/
> https://www.spamhaus.org/bgpf/
> http://arneill-py.sacramento.ca.us/cbbc/
> When configuring RPKI validation, here is what happens. 
> is a real-world example of a prefix that has been 
> blacklisted by three different RTBH feeds.
> After implementing RPKI validation, it has generated some volume of 
> firewall alarms for different type of attacks.
> c4321-michel#sh ip bgp | beg 152.89.196.
> BGP table version is 48156064, local router ID is
> Status codes: s suppressed, d damped, h history, * valid, > best, i - 
> internal,
> Origin codes: i - IGP, e - EGP, ? - incomplete
> RPKI validation codes: V valid, I invalid, N Not found
> Network          Next Hop            Metric LocPrf Weight Path
> I*                0     90      0 21719 I 
>              <== Trusted RTBH
> N* i                              100      1 i 
>                    <== CBBC
> I*                0     40      0 65190 i              <== 
> Spamhaus
> V*>                 30      0 1299 9002 57523 i    <== 
> Prefix from full feed
> The problem here is that RPKI validation is at the very top of the BGP 
> bestpath decision process, before weight and local-preference, without 
> any way to change that.
> Therefore, the “Valid” status of the RPKI route affectively renders 
> the RTBH feeds useless. No matter what manipulations of other 
> parameters may be configured in route-maps, the RPKI status will 
> override everything else.
> Unsurprisingly, Cisco says that doing something about it is impossible.
> Unfortunately, the “Valid” RPKI status presents no warranties 
> whatsoever that the prefix is not used for rogue activities. Same as 
> HTTPS certificates, crooks and spammers have realized that a ROA was a 
> necessary part of doing their dirty business.
> This particular prefix is a well-known source of attacks; there are 
> very valid reasons it is present in multiple BGP blackholes. 
> Unfortunately, RPKI validation, combined with Cisco’s implementation, 
> as provided bad actors with a tool to disable a blacklisting method 
> that plenty of orgs are currently using.
> I am forced to disable RPKI prefix validation. To me, RPKI prefix 
> validation does not bring enough value to compensate for the loss of 
> the protection that the BGP blackhole feeds provide. Implementing RPKI 
> validation has actually increased the volume of attacks on my network, 
> attacks that were previously blocked right at the very edge. The risk 
> increase is immediate : implementing RPKI validation is what made me 
> look at these new firewall alarms. On the other hand, the gain is not 
> immediately perceptible.
> In terms of public policy and ARIN, I think that there is a consensus 
> that deploying RPKI validation is good for everyone. I am posting this 
> so that the community can build an understanding of why it may not be 
> deployed universally. I am not deploying it because I don’t want it or 
> don’t understand it, I am not deploying it because it simply does not 
> work for me. I don’t think I will be the only one in that case. It 
> looked like a good idea on paper, but the impossibility to accommodate 
> currently implemented security measures is a no-go.
> Michel
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