The National Security Agency is secretly piggybacking on the tools that enable Internet advertisers to track consumers, using "cookies" and location data to pinpoint targets for government hacking and to bolster surveillance.

The agency's internal presentation slides, provided by former NSA contractor Edward Snowden, show that when companies follow consumers on the Internet to better serve them advertising, the technique opens the door for similar tracking by the government. The slides also suggest that the agency is using these tracking techniques to help identify targets for offensive hacking operations.