That's some cheap-ass pentesting. Here you go buddy! (j/k)
To explain the joke... companies spend tens of thousands doing "pentesting" to stave off vectors for concerted attacks. In this case, they would be spending tens of thousands to prevent the...$500 being extorted. My joke is that it is just as easy to pay the guy $500 for finding the errors. It's just a joke, though. You shouldn't pay extortionists a dime. (Even if that's all they ask for.)
There is some logic of burying wallet.dat files in various places in your systems and monitoring them. If/when they go missing, you know you have a problem.
Possibly set-up a periodic cycling system that drives the intruder to move them now, before they get cycled and might lose their bounty forever.
To explain the joke... companies spend tens of thousands doing "pentesting" to stave off vectors for concerted attacks. In this case, they would be spending tens of thousands to prevent the...$500 being extorted. My joke is that it is just as easy to pay the guy $500 for finding the errors. It's just a joke, though. You shouldn't pay extortionists a dime. (Even if that's all they ask for.)