Former Anonymous hacker: Block ISIS recruitment first

Anonymous's greatest tool against the self-proclaimed Islamic State (ISIS) is to cut off its online recruiting operations, a former hacker with the group said Friday.

"The hacking, it adds some sensationalism," Gregg Housh told CNBC's "Closing Bell." "But in the end I think the most important thing is to stop the recruiting."

Housh is co-founder of He said that tracking the terrorist group can be done through legal channels. Law enforcement also tracks Anonymous, he said.

Housh said that ISIS relies on social networking sites to recruit people — whether through Facebook, Twitter, or its own websites.

"The most effective is the currently legal things of reporting the accounts, shutting down the websites," he said.

"For the most part, the best thing here is that it is legal. They [Anonymous hackers] are not having to break the law, they're not having to break into systems to do this so anyone can take part," Housh said.