None have been successful at obtaining all of the malware's code, and the government appears to have no intention of handing it over.

Now, the FBI is classifying the Tor Browser exploit for reasons of national security, despite the exploit already being used in normal criminal investigations well over a year ago. Experts say it indicates a lack of organization or technical capabilities within the FBI.

"The FBI has derivatively classified portions of the tool, the exploits used in connection with the tool, and some of the operational aspects of the tool in accordance with the FBI's National Security Information Classification Guide," government attorneys wrote in a filing earlier this month. It came in response to the defense of Gerald Andrew Darby, who is charged with child pornography offenses.