In the past they have texted specific GRU agents on their personal phones: https://www.wired.com/story/cyber-command-ira-strike-sends-s...

> As The New York Times reported last October, Cyber Command operators sent direct messages to individual Russian staffers that they had identified as involved in election interference, and were tracking their activity. The Post reports that the IRA was troubled enough by those messages that they launched an internal investigation to identify potential leakers.

I have a feeling that the US and allied countries are pretty deep into the Russians with this stuff.