several of the techniques that are now used to break or compromise Microsoft Windows were first developed at that time, and used to explore UNIX systems.
These techniques include the use of buffer overflows,
port scanning, identity theft, man in the middle attacks against network protocols, etc.
The entire "black hat/white hat" hacker credo was started at that time inside the UNIX community.
But as Windows got more and more market share,
the bad guys simply moved their targets against it.