Route hijacking

BGP hijacking (sometimes referred to as prefix hijacking, route hijacking or IP hijacking) is the illegitimate takeover of groups of IP addresses by corrupting Internet routing tables maintained using the (BGP).

The Internet is a global network in enabling any connected host, identified by its unique IP address, to talk to any other, anywhere in the world. This is achieved by passing data from one router to another, repeatedly moving each packet closer to its destination, until it is safely delivered. To do this, each router must be regularly supplied with up-to-date routing tables. At the global level, individual IP addresses are grouped together into prefixes. These prefixes will be originated, or owned, by an autonomous system (AS) and the routing tables between ASes are maintained using the Border Gateway Protocol (BGP).

A group of networks that operate under a single external routing policy is known as an autonomous system. For example, Sprint, Verizon, and AT&T each are an AS. Each AS has its own unique AS identifier number. BGP is the standard routing protocol used to exchange information about IP routing between autonomous systems.

Each AS uses BGP to advertise prefixes that it can deliver traffic to. For example, if the network prefix 192.0.2.0/24 is inside AS 64496, then that AS will advertise to its provider(s) and/or peer(s) that it can deliver any traffic destined for 192.0.2.0/24.

Although security extensions are available for BGP, and third-party route DB resources exist for validating routes, by default the BGP protocol is designed to trust all route announcements sent by peers, and few ISPs rigorously enforce checks on BGP sessions.

IP hijacking can occur deliberately or by accident in one of several ways:

Common to these ways is their disruption of the normal routing of the network: packets end up being forwarded towards the wrong part of the network and then either enter an endless loop (and are discarded), or are found at the mercy of the offending AS.

Typically ISPs filter BGP traffic, allowing BGP advertisements from their downstream networks to contain only valid IP space. However, a history of hijacking incidents shows this is not always the case.

The Resource Public Key Infrastructure (RPKI) is designed to authenticate route origins via cryptographic certificate chains demonstrating address block range ownership, but is not widely deployed yet. Once deployed, IP hijacking through errant issues at the origin (via both accident or intent) should be detectable and filterable.

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Wikipedia