The National Security Agency (NSA) took advantage of the same technology used to gauge consumer behavior online, to bolster its surveillance of suspicious individuals and go on the offensive.

The latest documents provided to The Washington Post by whistleblower Edward Snowden reveal the agency’s snooping tactics.

Small tracking files, known as “cookies,” are typically used by internet advertisers to track a user’s web surfing history and serve them targeted ads. According to a report by The Washington Post, the NSA honed in on a Google-specific cookie known as “PREF.”

While they don’t collect personal information, such as names and email addresses, these cookies allowed the agency to track its targets’ web visits, identify their computer, and “enable remote exploitation.”