From the Wired article, "Instead of going for the easy bust, the FBI spent a solid year surveilling McGrath, while working with Justice Department lawyers on the legal framework for what would become Operation Torpedo. Finally, on November 2012, the feds swooped in on McGrath, seized his servers and spirited them away to an FBI office in Omaha.
A federal magistrate signed three separate search warrants: one for each of the three hidden services. The warrants authorized the FBI to modify the code on the servers to deliver the NIT to any computers that accessed the sites. The judge also allowed the FBI to delay notification to the targets for 30 days."
The FBI modified the .onion sites to serve a malicious script which was used to de-anonymize users. It's worth noting that only those using Tor improperly would be vulnerable. The FBI tracking payload required scripting to be enabled in the browser--a common blunder among inexperienced Tor users.
(Score: 3, Informative) by Runaway1956 on Wednesday August 06 2014, @06:03PM
It's definitely good and bad.
They busted some child porn freaks. That's good.
They found an exploit that makes it easy to deanonymize a Tor user if he doesn't set up Tor correctly. That is bad.
But, again on the good side - if you set Tor up properly, this exploit isn't supposed to work.
Abortion is the number one killed of children in the United States.