The FBI has uncovered a paedophile network by installing malware on suspects' computers.
The investigation agency has discovered 14 users of a site called Pedoboard by targeting users of the anonymous internet network Tor.
Tor is open-source software and allows people to browse the internet by routing traffic through a series of computers, so the user's location can't be found. It can also be used to surf hidden websites, such as those ending in the suffix .onion.
Both criminals and activists that want to escape prosecution for not supporting a country's regime, for example, use the browser.
The FBI sent out crawlers to find hidden websites distributing child abuse images and hacked them to install malware on a vistor's computer using the 'drive-by downloads' method.
The malware then sends information about the user back to the FBI.
The initiative forms part of Operation Torpedo, which was launched in 2012 as a way of cracking down on child abuse images being distributed and viewed on the internet.
The 'drive-by downloads' malware scheme has been used since 2002, but the FBI has only just started using it on a large scale, in the hope to capture more criminals.
However, the FBI still has a legal hurdle to get over. Lawyers defending those who were discovered using Pedoboard are saying the evidence provided by malware can't be used in court because it had concealed its use 'beyond the period allowed in the search warrant.'
Last year, the FBI used a vulnerability in Mozilla's Firefox browser to bring down a paedophile ring by installing a JavaScript injection to compromise the Tor network and uncover users.
