AS Number hijacking due to misconfiguration

Anurag Bhatia
This Sunday I was looking at global routing table dump and found AS1 announcing some very weird prefixes. AS1 i.e Autonomous System Number 1 belongs to Level3 but as far as I know they are not actively using it. They use AS3356 globally (along with Global Crossing’s AS3549). I noticed quite a few prefixes of a Brazil based telecom provider - Netvip Telecomunicaes being announced by AS1. Some of entries in global routing table belonging to AS1 (as picked from BGP table dump of route-views archive):