Using Link Cuts to Attack Internet Routing

Attacks on the routing system, with the goal of diverting traffic past an enemy-controlled point for purposes of eavesdropping or connection-hijacking, have long been known. In principle, at least, these attacks can be countered by use of appropriate authentication techniques. We demonstrate a new attack, based on link-cutting, that cannot be countered in this fashion. Armed with a topology map and a list of already-compromised links and routers, an attacker can calculate which links to disable, in order to force selected traffic to pass the compromised elements. The calculations necessary to launch this attack are quite efficient; in our implementation, most runs took less than half a second, on databases of several hundred nodes. We also suggest a number of work-arounds, including one based on using intrusion detection systems to modify routing metrics.