What is cryptojacking?

We’ve covered myriad types of malware and cyber attacks on the blog over the years, and few are as insidious as cryptojacking. Because it’s a relatively new scam that has only come to the fore in recent years, many people haven’t yet heard of it. 

Cryptojacking involves the unauthorized use of other people’s devices to mine for cryptocurrency without the victims even realizing it. On the surface, cryptojacking may not seem as severe when compared to other cyber attacks. Its aim is not to steal or exploit personal data or damage your computer but “just” to use its processing power. However, cryptojacking is still a crime and can have other consequences for victims beyond what you’d typically expect. 

This blog post will discuss how cryptojacking works, why it’s appealing to hackers, the consequences of cryptojacking, and how to protect yourself from becoming a victim. 

Before we jump into how exactly cryptojacking works, here’s a quick primer of what cryptocurrency is and what mining it involves.

Cryptocurrency and cryptomining

Cryptocurrency is a type of digital currency that exists only in the online world rather than in any tangible form. The most famous example is bitcoin, but there are thousands more. All cryptocurrency transactions occur in an encrypted digital ledger known as a blockchain, usually located on a decentralized peer-to-peer network. This is actually one of cryptocurrency’s main appeals. People can trade financial assets without any fear of outside interference. Because there is no oversight as such, all the computers on the network work together to confirm and authenticate a transaction. If anyone tries to interfere with the ledger or change something, everyone on the network will be alerted. 

So, where does crypto mining come into it? Well, that’s when transactions, also known as blocks, are added to the blockchain. Cryptominers are in charge of adding these blocks to the chain. Every time a new transaction occurs, miners must solve a cryptographic equation to validate the data blocks that record it in the blockchain. For every block they add, a miner is rewarded with a certain amount of cryptocurrency. 

A great deal of computing power is needed to solve these equations, so miners need a lot of dedicated hardware, and sometimes several computers, to solve these puzzles. As you can imagine, the cost of equipment and electricity bills can get very high. Because of the high costs associated with cryptomining, it can be very difficult for ethical miners to turn a profit. 

For less ethical miners, there’s cryptojacking.

How cryptojacking works

Hackers secretly install cryptojacking software on the victim’s device. The two most common methods of doing this are:

1. An online ad or website injected with a malicious javascript code that executes when the victim loads it on their browser.
2. Phishing: The hacker sends the victim an email or text with a malicious link that downloads the cryptojacking software to their computer.

Once the malware has been installed or executed, it gets to work mining. Because this malware is programmed to work in the background, generally, device owners don’t notice that anything is wrong, other than their computer suddenly running a little slower than usual. 

This is generally harmless to the computer (and annoying for the user!), but not always. Increased processor usage can lead to the device overheating and may even damage it. Businesses may need to devote costly IT resources to find the cause of multiple computers suddenly facing performance issues. Not to mention the suddenly spiking electricity bills that come from the computers working overtime. 

Beyond that, who wants to find out that their device has been used for illicit gain unbeknownst to them? 

How to protect yourself

Because this type of malware can be so insidious, often running without the victim even realizing it, it’s critical to know the signs to watch out for:

1. A sudden decrease in computer performance: This can include your device crashing, running slowly, or the battery running out faster than usual. 
2. Unusual central processing unit (CPU) usage: If you notice that you’re on a pretty basic website that coincides with a sudden uptick in CPU usage, that could be a sign the site is running cryptojacking scripts on your device. However, finding the origins of that usage might be difficult. 
3. Your computer is overheating, or the fan is running faster than usual: Because cryptojacking uses so many resources, overheating is a common repercussion. 

As always, a good antivirus program is essential for preventing unexpected malicious downloads on your device.  Browser extensions like NoMiner and minerBlock will stop illicit miners from exploiting your web browser. Make sure to keep all your software updated, as out-of-date software is a common way for malicious actors to gain access to your device. Lastly, be mindful of social engineering and potential phishing scams. Never click a link enclosed in an email, instant message, or SMS that has come from an unfamiliar source. 

Wrap up

In the last couple of years, cryptojacking has declined, with law enforcement stepping up and shutting down Coinhive, one of the worst culprits for spreading the malicious browser javascript, in 2019. However, cryptojacking hasn’t gone away entirely, not by a long shot — it actually saw an increase in the first quarter of 2021. However, by taking the proper precautions and keeping an eye on any unusual performance of your digital device, you should be able to avoid becoming a victim. 

For more on how to protect yourself from malware and cybercrime, check out this blog post on avoiding phishing and smishing scams, as well as our blog on protecting your computer from malware.