Sandbox

One important safety measure on computers is the practice
of sandboxing ie isolating new code from the existing one, and
explicitly asking permission from the user to access or make changes.
Anyone who has updated Java has had this experience. Indeed,
the below explanation mentions that web browsers themselves run
in sandboxed environments. So the criminal ransomware Wanna code
had somehow breached these security features.

And it could be stopped by registering a domain name, which contained
kill code. Once the domain name was activated, the ransomware would
contact it and desactivate itself.

I am  including a link to Le Monde's Pixel feature, a tech blog
on the daily from which I got the Huss copy of the kill code.

https://www.howtogeek.com/169139/sandboxes-explained-how-theyre-already-protecting-you-and-how-to-sandbox-any-program/

http://www.lemonde.fr/pixels/article/2017/05/14/cyberattaque-comment-un-jeune-anglais-est-devenu-un-heros-accidentel_5127619_4408996.html

http://www.lemonde.fr/pixels/