What is cryptojacking?

Cryptojacking is defined as the secret use of your computing device to mine cryptocurrency.

Cryptojacking used to be confined to the victim unknowingly installing a program that secretly mines cryptocurrency.

Here's the bad news...

In-browser cryptojacking doesn't need a program to be installed.

I found this out when Jascha, a Hacker Bits subscriber, emailed us about an article in Issue 22 that was doing in-browser cryptojacking.

Below, you'll find out more about in-browser cryptojacking and how to protect yourself.

How does in-browser cryptojacking work?

In-browser cryptojacking uses JavaScript on a web page to mine for cryptocurrencies.

JavaScript runs on just about every website you visit, so the JavaScript code responsible for in-browser mining doesn't need to be installed.

If you think it's nothing, think again...

You load the page, and the in-browser mining code just runs. No need to install, and no need to opt-in.

Currently (Nov 2017), in-browser mining is available for the Monero cryptocurrency.

Cryptojacking with JavaScript

A cryptojacking JavaScript web page uses your computer to mine for cryptocurrencies.

What is Monero cryptojacking?

Monero is a privacy-focused cryptocurrency started in 2014. It is one of the few cryptocurrencies that supports in-browser mining.

Cryptojacking scripts

Cryptojacking scripts allow you to quickly install a miner on your website. Coinhive’s set of AuthedMine scripts is the only solution I can recommend.

Cryptojacking tutorial

This tutorial is a cryptojacking how-to detailing exactly what you need to setup an opt-in WordPress Coinhive miner for the Monero cryptocurrency.

Cryptojacking blocker

The simplest way to protect yourself from cryptojacking is to install a cryptojacking blocker.

Want to know more about cryptocurrencies?

Checkout Cryptominded for a curated collection of some of the best cryptocurrency resources. The Starters' Guide is fantastic.

If you're okay with being cryptojacked and like living on the edge, you can also checkout Issue 22. The link to A Guide to Crypto Currencies is also a great guide.

Big thanks... for reviewing earlier versions of this article: Shea Newkirk (aka The 'Stache), Jascha, Brian D. Colwell, Edmond Chan and Kyle Rea.

Update 12/15/2017: The Sun is plagiarizing this article. Not going to link to it, but you can find it with a quick search. They clearly stole passages from this article.

Update 12/19/2017: This article is included in Decryptionary!! Thanks, Dani.

Update 1/11/2018: We're in Blockchain WTF's intermediate glossary!

Update 1/22/2018: Thanks to David for including this article in Bitcoin Security Tips.

Update 1/24/2018: BlockchainHub included this article. Thanks, Valentin!

About the Author

Ray Li

Ray is a software engineer and data enthusiast who has been blogging for over a decade. He loves to learn, teach and grow. You’ll usually find him wrangling data, programming and lifehacking.