"Man in the middle" attacks would let the spy agency gather data without breaking encryption.
Buried in a Brazilian television report on Sunday was the disclosure that the NSA has impersonated Google and possibly other major internet sites in order to intercept, store, and read supposedly secure online communications. The spy agency accomplishes this using what's known as a "man-in-the-middle (MITM) attack," a fairly well-known exploit used by elite hackers. This revelation adds to the growing list of ways that the NSA is believed to snoop on ostensibly private online conversations.
In what appears to be a slide taken from an NSA presentation that also contains some GCHQ slides, the agency describes "how the attack was done" on "target" Google users. According to the document, NSA employees log into an internet router—most likely one used by an internet service provider or a backbone network. (It's not clear whether this was done with the permission or knowledge of the router's owner.) Once logged in, the NSA redirects the "target traffic" to an "MITM," a site that acts as a stealthy intermediary, harvesting communications before forwarding them to their intended destination.