A new type of cybercrime known as cryptojacking is on the rise. Cybercriminals engaging in this activity are not looking to steal your money or your data. Instead, they want to steal your computer’s processing power. What do they do with this power? To answer this question, a quick primer in cryptocurrencies is needed.

Cryptocurrencies and Mining

Cryptocurrencies like Bitcoin and Monero are a type of digital currency. Unlike other digital and nondigital currencies, there is no central authority overseeing the transfer of funds and creation of new units. Plus, there is no centralized server on which information about accounts, balances, and transactions is recorded and stored. Instead, cryptocurrencies are regulated through cryptography and a peer-to-peer (P2P) network (i.e., a network of computers, in which each machine acts as the server for the files stored on it).

When cryptocurrency changes hands, encrypted files are created. For example, if Wanda gives Willy a Bitcoin, a file noting the exchange is created and signed by Wanda’s private key. This transaction file is sent to every computer in the P2P network.

Although the computers receive the transaction almost immediately, the transaction is not official until it is verified. Once confirmed, it becomes part of the cryptocurrency’s historical records. Every computer in the P2P network stores the complete history of the cryptocurrency’s accounts, balances, and transactions.

The people who verify cryptocurrency transactions are known as miners. These transactions are bundled into groups. To verify the legitimacy of a group of transactions, miners need to solve a cryptographic puzzle. The first miner who solves the puzzle is compensated with a unit of the cryptocurrency (e.g., a Bitcoin). Solving cryptographic puzzles is the only way new cryptocurrency units can be created.

Besides taking a lot of time, it takes an enormous amount of computing power to solve these puzzles. Miners have come up with a creative but somewhat shady way to get more power — cryptojacking.


To get the power needed to solve cryptographic puzzles, some miners resort to using website scripts that siphon processing power from visitors’ computers. A few websites openly advertise this fact, presenting it as a trade-off for not having ads on their sites. However, these scripts are often used to hijack visitors’ processing power without their knowledge or consent. The latter is referred to as cryptojacking.

Cryptojacking activity spiked at the end of 2017, according to researchers at Malwarebytes. For example, in October 2017, Malwarebytes blocked around 8 million requests per day to domains hosting these scripts. Part of the reason for this increase is that cybercriminals have started using these scripts to get computing power for their exploits. They either add these scripts to their own malicious web pages or they hack into legitimate sites and insert the scripts there.

How to Protect Your Business’s Computers from Cryptojacking

Compared to ransomware or data breaches, cryptojacking might seem like a minor annoyance. However, it can be detrimental to your business’s computers. They can become sluggish because of the extra load put on their processors. The processors can also overheat, which might lead to computers freezing or crashing.

Fortunately, a cryptojacking script works only when someone is visiting the site hosting it. When the person leaves the site, the siphoning of processing power will stop. Still, it is best not to let this happen in the first place. A good ad or script blocker will prevent malicious scripts from loading. There are also third-party tools you can use designed specifically for blocking cryptojacking scripts.

Plus, if your company hosts a website, you might want to make sure that hackers have not placed a cryptojacking script on it. We can examine your site for this type of script as well as look for other security issues.