Validating possible BGP MITM attack

Steve Feldman feldman at
Thu Aug 31 17:23:04 UTC 2017

Interesting.  We also got similar BGPMon alerts about disaggregated portions of couple of our prefixes. I didn't see any of the bad prefixes in route-views, though.

The AS paths in the alerts started with "131477 38478 ..." and looked valid after that.  Job's suggestion would explain that.


> On Aug 31, 2017, at 10:01 AM, Job Snijders <job at> wrote:
> Hi Andy,
> It smells like someone in 38478 or 131477 is using Noction or some other
> BGP "optimizer" that injects hijacks for the purpose of traffic
> engineering. :-(
> Kind regards,
> Job
> On Thu, 31 Aug 2017 at 19:38, Andy Litzinger <andy.litzinger.lists at>
> wrote:
>> Hello,
>> we use to monitor our BGP announcements.  This morning we
>> received two possible BGP MITM alerts for two of our prefixes detected by a
>> single BGPMon probe located in China.  I've reached out to BGPMon to see
>> how much credence I should give to an alert from a single probe location,
>> but I'm interested in community feedback as well.
>> The alert detailed that one of our /23 prefixes has been broken into /24
>> specifics and the AS Path shows a peering relationship with us that does
>> not exist:
>> 131477(Shanghai Huajan) 38478(Sunny Vision LTD) 3491(PCCW Global) 14042
>> (me)
>> We do not peer directly with PCCW Global.  I'm going to reach out to them
>> directly to see if they may have done anything by accident, but presuming
>> they haven't and the path is spoofed, can I prove that?  How can I detect
>> if traffic is indeed swinging through that hijacked path? How worried
>> should I be and what are my options for resolving the situation?
>> thanks!
>> -andy

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