I just learned the hard way the old VBS kill script listed here - https://www.sparklabs.com/support/viswin_scripting/ - does not work in Windows 8.1 I recently upgraded from 7 to 8.1. My VPN went down this evening while using it, and I was transferring data in the clear for some time before I noticed.

However, a simple Batch file will work with Windows 8.1.

A single line - TASKKILL /PID programnamehere.exe - in Notepad and then saved as a .bat file (for example, kill.bat) works just fine for me. Of course, use the correct name of the program in place of "programnamehere.exe" such as firefox.exe or utorrent.exe, whatever you want turned off if your VPN drops.

Put the .bat file in a safe place on your C: drive, and then go into each Viscosity VPN connectoid, go to Advanced, and link to it in the Disconnected Script selector.