The U.S. is still probing the extent of a recent cyber leak of what purports to be hacking tools used by the National Security Agency.

Director of National Intelligence James Clapper says intelligence officials are trying to sort it out.

The tool kit consists of malicious software intended to tamper with firewalls, the electronic defenses protecting computer networks.

The leak has set the information security world atwitter — and sent major companies rushing to update their defenses.

Clapper says the U.S. still doesn't know the full extent of exactly what happened.

He spoke Wednesday at the Nixon Presidential Library and Museum in Yorba Linda, California.

The documents have been leaked by a group calling itself the "Shadow Brokers," but many have floated the possibility of Russian involvement.