Earlier quoted context omitted.
If some journalists were able to find his identity, he can safely assume that the people behind wannacry are also able to do it. How do you figure? Digging through information and finding out this sort of stuff is literally what journalists do for a living.
I occasionally offer to dox people to show them how bad their OpSec truly is or as an example of why I don't use social media like Facebook for privacy concerns. Doxing people is often trivial since nearly anyone contributing to discussions online have large online profiles. It isn't a very difficult task - just a game of connecting the dots and knowing how to construct specific Google search queries (eg: "site:___ +…
News organizations have access to many non-public databases.