Canada's Communications Security Establishment (CSE), an equivalent to the US National Security Agency (NSA), focuses on electronic surveillance. It can access data from over 100 global free upload sites, monitoring downloaded content in countries across Europe, the Middle East, North Africa, and North America, suggests a covert operation revealed by CBC News in collaboration with The Intercept journalist Glen Greenwald.

According to documents released in 2012 and obtained by NSA whistleblower Edward Snowden, which were recently revealed to CBC, the project – dubbed Levitation – tracks data from 102 file-sharing websites, with popular sources such as Sendspace, Rapidshare, and the now-defunct Megaupload among them.

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"No organization has the ability/permission to trawl/search Sendspace for data," the file-hosting service told CBC News. Sendspace's policy states it won't disclose user identities unless legally required. Levitation documents say its access to databases used to track the online traffic of millions of people around the world comes from unnamed "special sources."

CSE analysts have access and sort through 10 to 15 million upload or download events daily, searching for "the interesting ones," among music, video, photo, and other files, the document says.

Apparently our government watches what you download http://t.co/RIoVc7lYZg #kw http://ift.tt/1LimJ1K

— Colin Butler (@CBCColinButler) January 28, 2015

When scouring the file-sharing sites, spies from the Levitation program allegedly closely watch suspicious content – such as hostage videos or explosive making instructions – and then trace users' IP addresses to follow cookies and identify suspects who could be connected to extremism or terrorism. After "filtering out Glee episodes," as the presentation puts it, about 350 "interesting download events" – less than 0.0001 percent of the total collected traffic – are identified by the agency each month.

"You could be finding a terrorist, although probably much more likely you're finding a scientist, or a journalist, or a lawyer working on a case relating to some of those issues, or a student," Glenn Greenwald told CBC News.

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The discovery of a German hostage video and an uploaded document that contained the hostage strategy of an Al-Qaeda-linked terrorist organization are cited in the 2012 presentation. No other instances are mentioned, leaving it unclear if any other terrorist attacks have been prevented through intercepting and analyzing the data. The leaked document has no answers on whether Levitation is still in use or for how long it has been active.

"It's really the first time that a story has been reported that involves [CSE] as the lead agency in a program of pure mass surveillance," Greenwald said, commenting on Canada's role in international spying programs, according to the Snowden documents. Canada is part of the Five Eyes intelligence sharing network, along with the US, Britain, Australia, and New Zealand.