It is this leaker that provided secret and classified documents that formed the basis of The Intercept's latest story about the US government’s Terrorist Screening Database.
The source of the documents - prepared by the National Counterterrorism Center in August 2013, and stamped “SECRET” and “NOFORN” (not to be shown to foreign governments) - is someone working in the intelligence community. It's definitely not Snowden himself, as the documents were compiled after he left the USA.
It is still unknown whether this source has shared other documents with journalists (Intercept's or those working for other media), but the US government would be wise to assume that this article is not the end of these leaks.
Snowden hoped that other whistleblowers will be influenced by his actions, and it seems he's not the only one ready to take the risk of being caught.
Whatever protections the intelligence community has set up to prevent malicious insiders to exfiltrate secret documents is obviously not foolproof.