Re: RESOLVED: Cogent Abuse - Bogus Propagation of ASN 36471

[Giorgio Bonfiglio via NANOG <nanog () nanog org>]

Do you mind following up on Matthew’s request for details - really interested to see the threat model there and how the 
RPKI part played out?

On 20 Jul 2023, at 18:06, Pete Rohrman <prohrman () stage2networks com> wrote:

 

All,

 


 

 

Cogent has shut down the compromised router.  This issue is resolved.  Thank you all for your help.

 


 

 


 

 


 
Pete 
 
 
Stage2 "Survivor Island" Bronze Medal Winner
 

 
 

 
 

 
 
On 7/20/23 12:59, Mike Hammett wrote:
 
 
If they (or anyone else) want to give me free service to use as I see fit (well, legally), I'll gladly accept their 
offer.
 
 

 
 -----
 Mike Hammett
 Intelligent Computing Solutions
 http://www.ics-il.com
 
 Midwest-IX
 http://www.midwest-ix.com
 
 
 
--------------------------------
 
From: "Tom Beecher" <beecher () beecher cc>
 To: "Matthew Petach" <mpetach () netflight com>
 Cc: nanog () nanog org
 Sent: Thursday, July 20, 2023 11:38:50 AM
 Subject: Re: Cogent Abuse - Bogus Propagation of ASN 36471
 
 
 In short--I'm having a hard time understanding how a non-paying entity still has working connectivity and BGP 
sessions, which makes me suspect there's a different side to this story we're not hearing yet.   ^_^;
 

 
 
I know Cogent has long offered very cheap transit prices, but this seems very aggressive! :)  
 
 
 
 
On Thu, Jul 20, 2023 at 12:28 PM Matthew Petach <mpetach () netflight com <mailto:mpetach () netflight com> > wrote:
 
 
 

 
 
 
 
On Thu, Jul 20, 2023 at 8:09 AM Pete Rohrman <prohrman () stage2networks com <mailto:prohrman () stage2networks com> > 
wrote:
 
 
 

Ben,

 

Compromised as in a nefarious entity went into the router and changed passwords and did whatever.  Everything 
advertised by that comprised router is bogus.  The compromised router is owned by OrgID: S2NL (now defunct).  AS 36471 
belongs to KDSS-23 <https://search.arin.net/rdap?query=KDSS-23&amp;searchFilter=entity> .  The compromised router does 
not belong to Kratos KDSS-23 <https://search.arin.net/rdap?query=KDSS-23&amp;searchFilter=entity> , and is causing 
routing problems.  The compromised router needs to be shut down.  The owner of the compromised router ceased business, 
and there isn't anyone around to address this at S2NL.  The only people that can resolve this is Cogent.   Cogent's 
defunct customer's router was compromised, and is spewing out bogus advertisements.  
 

 

Pete

 
 

 
 

 
 
Hi Pete,
 

 
 
This seems a bit confusing. 
 

 
 
So, S2NL was a bill-paying customer of Cogent with a BGP speaking router.
 
They went out of business, and stopped paying their Cogent bills.
 
Cogent, out of the goodness of their hearts, continued to let a non-paying customer keep their connectivity up and 
active, and continued to freely import prefixes across BGP neighbors from this non-paying defunct customer.
 
Now, someone else has gained access to this non-paying, defunct customer's router (which Cogent is still providing free 
connectivity to, out of the goodness of their hearts), and is generating RPKI-valid announcements from it, which have 
somehow not caused a flurry of messages on the outages list about prefix hijackings.
 

 
 
The elements to your claim don't really seem to add up.
 
1) ISPs aren't famous for letting non-bill-paying customers stay connected for very long past the grace period on their 
billing cycle, let alone long after the company has gone belly-up.
 
2) It's not impossible to generate RPKI-valid announcements from a hijacked network, but it's very difficult to 
generate *bogus* RPKI-valid announcements from a compromised router--that's the whole point of RPKI, to be able to 
validate that the prefixes being announced from an origin are indeed the ones that are owned by that origin.
 

 
 
Can you provide specific prefix and AS_PATH combinations being originated by that router that are "bogus" and don't 
belong to the router's ASN?

 

 
 
If, however, what you meant is that the router used to be ASN XXXXX, and is now suddenly showing up as ASN 36471, and 
Cogent happily changed their BGP neighbor statements to match the new ASN, even though the entity no longer exists and 
hasn't been paying their bills for some time, then that would imply a level of complicity on Cogent's part that would 
make them unlikely to respond to your abuse reports.  That would be a very strong allegation to make, and the necessary 
level of documented proof of that level of malfeasance would be substantial.
 

 
 
In short--I'm having a hard time understanding how a non-paying entity still has working connectivity and BGP sessions, 
which makes me suspect there's a different side to this story we're not hearing yet.   ^_^;
 

 
 
Thanks!
 

 
 
Matt