An elite US cyber team that has stealthily tracked Internet villains for more that a decade pulled back its cloak of secrecy to recruit hackers at a notorious DefCon gathering here.

Vigilant was described by its chief Chet Uber as a sort of cyber "A-Team" taking on terrorists, drug cartels, mobsters and other enemies on the Internet.

"We do things the government can't," Uber said yesterday. "This was never supposed to have been a public thing."

Vigilant is an alliance of slightly more than 600 volunteers and its secret ranks reportedly include chiefs of technology at top firms and former high-ranking US cyber spies.

The group scours Internet traffic for clues about online attacks, terrorists, cartels and other targets rated as priorities by members of the democratically run private organisation.

Vigilant also claimed to have "collection officers" in 22 countries that gather intelligence or coordinate networks in person.

"We go into bars, look for lists of bad actors, get tips from people..." Uber said.

"But, a significant amount of our intelligence comes from our monitoring the Internet. We are looking at everything on websites, and websites are public."

He was adamant that Vigilant stays within US law while being more technologically nimble than government agencies weighed down by bureaucracy and internal rivalries.

"Intelligence is a by-product of what our research is," Uber said. "Our research is into attacks, why they happen and how we can prevent them."

Vigilant shares seemingly significant findings with US spy agencies, and is so respected by leading members of the hacker community that Uber was invited to DefCon to recruit new talent.

Uber said that Vigilant came up from underground after 14 years of operation in a drive to be at "full capacity" by adding 1,750 "vetted volunteers" by the year 2012.

"We are good people not out to hurt anybody," Uber said. "Our one oath is to defend the US Constitution against all enemies foreign and domestic.