Two security researchers have demonstrated a new technique to stealthily intercept internet traffic on a scale previously presumed to be unavailable to anyone outside of intelligence agencies like the National Security Agency.

The tactic exploits the internet routing protocol BGP Border Gateway Protocol to let an attacker surreptitiously monitor unencrypted internet traffic anywhere in the world, and even modify it before it reaches its destination.

The demonstration is only the latest attack to highlight fundamental security weaknesses in some of the internet s core protocols. Those protocols were largely developed in the 1970s with the assumption that every node on the then-nascent network would be trustworthy. The world was reminded of the quaintness of that assumption in July, when researcher Dan Kaminsky disclosed a serious vulnerability in the DNS system. Experts say the new demonstration targets a potentially larger weakness.

It s a huge issue. It s at least as big an issue as the DNS issue, if not bigger, said Peiter Mudge Zatko, noted computer security expert and former member of the L0pht hacking group, who testified to Congress in 1998 that he could bring down the internet in 30 minutes using a similar BGP attack, and disclosed privately to government agents how BGP could also be exploited to eavesdrop. I went around screaming my head about this about ten or twelve years ago…. We described this to intelligence agencies and to the National Security Council, in detail.

The man-in-the-middle attack exploits BGP to fool routers into re-directing data to an eavesdropper s network.

Anyone with a BGP router ISPs, large corporations or anyone with space at a carrier hotel could intercept data headed to a target IP address or group of addresses. The attack intercepts only traffic headed to target addresses, not from them, and it can t always vacuum in traffic within a network — say, from one AT&T customer to another.

The method conceivably could be used for corporate espionage, nation-state spying or even by intelligence agencies looking to mine internet data without needing the cooperation of ISPs.

BGP eavesdropping has long been a theoretical weakness, but no one is known to have publicly demonstrated it until Anton Tony Kapela, data center and network director at 5Nines Data, and Alex Pilosov, CEO of Pilosoft, showed their technique at the recent DefCon hacker conference. The pair successfully intercepted traffic bound for the conference network and redirected it to a system they controlled in New York before routing it back to DefCon in Las Vegas.

The technique, devised by Pilosov, doesn t exploit a bug or flaw in BGP. It simply exploits the natural way BGP works.