You can notice it because when someone is visiting one of these sites that embeds cryptocurrency mining code it maxes out the visitor’s CPU.
You can make a test by visiting the Cryptojacking test site to see if you are vulnerable.
How to block cryptojacking?
Some developers have realized browser extensions that can block these scripts:
Users that already have an Ad blocker can add the list from adblock-nocoin-list Github project to prevent mining scripts.
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