Is your computer secretly mining Bitcoin alternatives? A beginner’s guide to ‘cryptojacking’

Bill Buchanan Read more December 20, 2017

Nothing comes for free, especially online. Websites and apps that don’t charge you money for their services will often rely on your data or advertising. Now, some sites have found a way to make money from you: using your computer to generate virtual currencies.

Is your computer secretly mining Bitcoin alternatives? A beginner's guide to ‘cryptojacking'

Several video streaming sites, including Openload, Streamango, Rapidvideo and OnlineVideoConverter, as well as file-sharing network The Pirate Bay have allegedly been “cryptojacking” their users’ computers in this way, as has a free Wi-Fi provider in a Starbucks cafe in Argentina.

What is cryptojacking?

Units of cryptocurrencies such as Bitcoin aren’t created by a central bank but are, instead, generated or “mined” by computers solving complex equations. Cryptojacking involves using someone’s computer without their knowledge, perhaps for just seconds at a time, to carry out these equations to mine cryptocurrency.

In the case of Bitcoin, mining requires specialised hardware and consumes masses of energy. For example, each Bitcoin transaction takes enough energy to boil around 36,000 kettles filled with water. In a year, the whole Bitcoin mining network consumes more energy than Ireland.

But Bitcoin is not the only show in town and there are many competing cryptocurrences. One of the most successful is Monero, which builds a degree of privacy into transactions (something Bitcoin doesn’t do). Currently it requires no specialised hardware for mining, so anyone with computing power to spare can mine it.

READ NEXT: How to buy Bitcoin in the UK

Mining usually takes the form of a competition. Whichever computer solves the equation the fastest is rewarded with the money. With Moreno and other similar cryptocurrencies, a pool of computers can work together and share the reward if they win the competition. This allows individual computers to work on a just small part of the mining task. The larger the pool, the more chance there is of winning the reward.

When a computer is cryptojacked, it is added to a pool to work on the task. This is often done using a commercially available piece of software, such as Coinhive, which can be written into what looks like an ad using the common website language JavaScript. As the ad runs in the background, the computer is added to a pool.

This means the website or internet provider doing the cryptojacking can mine cryptocurrency with little cost to themselves. One estimate is that 220 of the top 1,000 websites in the world are conducting cryptojacking, making a total of £32,000 over a three-week period.

The problem for the computer’s owner is that this takes up processor power, making other operations take much longer. Pirate Bay users have complained their processors have been using up to 85% of their capacity compared with less than 10% for normal operations. This can be accompanied by a large battery drain. The Pirate Bay has since said this high processor usage was a bug and the system should normally use between 20% and 30% of processing power.

How to avoid being cryptojacked?

Coinhive strongly advises the websites that deploy it that should inform users they are being cryptojacked. But it’s common for the code to run without users realising and without a way to opt out. If you want to prevent your computer from being cryptojacked you need a software tool which checks the code as it runs such as an ad-blocker.

But you might feel that allowing a site to use a little bit of your computer’s processing power is a better alternative to being bombarded with advertising. Whatever you do, you’ll likely end up paying for “free” services somehow.

Bill Buchanan is head of The Cyber Academy at Edinburgh Napier University. This article was originally published on The Conversation.

Image: Max Pixel