[BBC] GCHQ and NSA 'track Google cookies'

The latest Snowden leak suggests US and UK cyberspies are taking advantage of Google's proprietary cookie technology in an effort to track suspects.

Documents published by the Washington Post refer to the NSA and GCHQ's use of "GooglePrefIDs" - files containing a numeric code placed on
computers to help the search firm remember users. [...]

A document published by the Washington Post suggests the spy agencies also track other types of cookies, but does not specify which.

It is not clear how the authorities would have obtained the information, although the paper notes that it is among the data the NSA can demand through a Foreign Intelligence Surveillance Act (Fisa) court order. [...]