The nighttime activity and the disappearing disk space pointed to a security issue. They quickly changed all the account passwords and deleted all the files we stored on the system. It was a challenge, but Lenny and I weren’t deterred. We just kept hacking back in, night after night, despite their best efforts. In fact, because the staff and users of the system didn’t realize that we had their personal workstations under our control and could intercept their keystrokes, it was easy for us to immediately obtain their new log-in credentials every time they changed them.