My firm was referred to a firm that needed us through the leader of the local Python user group.
The client needed us to review code and act as a witness in a court case on very short notice.
It was interesting work, but a bit frightening once we did some research into the black hat hacker who had been warring with the client.
I would say to make sure you are hiring a WHITE hat hacker, and pay accordingly. Do your research, check recommendations by past clients and the community, and do a background check at minimum.