What Is Cryptojacking?

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by Oluwapelumi Adejumo · 8 min read
What Is Cryptojacking?
Photo: Depositphotos

Cryptojacking in recent times has become widespread as hackers are getting more sophisticated in their attacks. Read this guide to learn what it is and how you can detect it.

Cryptojacking is one form of cyberattacks on the internet. In this attack, a hacker uses an unsuspecting individual’s processing power to mine cryptocurrency for his personal use and gain.

It can also be said to be the unauthorized use of a computing system or tablets and mobile phones to mine for crypto assets like Bitcoin, Ethereum, Monero, and the rest.

To put it briefly, cryptojacking hackers tend to use their victims’ systems to perform all of the necessary updates needed for a blockchain, which would then lead to the mining of new tokens. A hacker then takes these new tokens (profits) while the victim bears the brunt of the cost of mining, the possible wear and tear that might have occurred to his system, and the, mostly, high cost of electricity that is needed to power the system.

What Is Cryptocurrency Mining?

We know that physical money is printed and distributed by the central government of every country. But what about cryptocurrencies? Since there is no central government to print and distribute these assets because it is a virtual currency, where does it come from? That is the multimillion question that has always baffled many.

Well, the answer is that these assets are created through a process called mining. Mining is a detailed, costly, and sometimes rewarding process of adding transaction records to the public ledger of past transactions popularly known as the blockchain.

Crypto mining is carried out by a set of specialized computers that can churn out a high hash rate. A higher hash rate significantly increases your chances of solving the mathematical problems involved in creating a new bitcoin.

Those who are involved in this process of creating these digital assets are called Miners. The rate at which new Bitcoin, for example, appears is almost the same as the way products like gold are mined from the ground. This is what informs the decision to label the process of getting new coins as mining.

Miners generally serve the crypto community by confirming legitimate transactions and helping the community effectively curb double-spending, i.e., miners in the community confirm every single transaction and make sure that community members do not re-spend the money that has been spent elsewhere.

Essentially, miners can be likened to auditors whose sole duty is to ensure that users of cryptocurrencies are honest in their dealings with other users. Thus, a miner is rewarded with a certain quantity of the asset once he has been able to verify transactions of a certain threshold.

In the case of the leading crypto asset, Bitcoin, the figure stands at 1MB. However, it is worthy to note that it is not everyone who verifies transactions that are rewarded. Why is this? The answer is that for a miner to get his reward, he would need to be the first to get the closest right answer to the mathematical problem posed by the network. In broader terms, this painstaking process is known as proof of work.

It means that every miner to get rewarded needs hard work and a tinge of luck to be the first to get the 64-digit hexadecimal number that is commonly referred to as a “hash.” This hash, at all times, must be less than or equal to the targeted hash. Simply put, it is a lot of guesswork that requires some luck.

Miners guess for this hash by using their computers to generate as many “nonces” as possible randomly, and as fast as possible. A nonce, also known as a number only used once, is the key to generating a hash that is either less than or equal to the targeted hash. A miner is then awarded credit for completing the block and given a certain quantity of bitcoin.

It is because of the above reason that miners tend to spend quite a lot on a good ton of computing power that can give them a very high “hash rate,” which can be measured in megahashes per second (MH/s), gigahashes per second (GH/s), and terahashes per second (TH/s). That is quite a whole lot of hashes in seconds.

In short, miners help secure the crypto network. As we stated earlier, miners help mint new coins into circulation; without them, there would be no new digital assets in circulation.

How Does Cryptojacking Work?

One truth is that there are quite several ways to infiltrate a computer system by a hacker. One of the common ways is through the use of classic malware.

In this case, a targeted victim unknowingly clicks on a malicious link that may be lying in his e-mail or even in one corner of the internet, and it begins to unload a crypto mining code onto your system. Once this code launches on your device, the hacker begins to work round the clock to mine crypto assets through your device. In contrast, the victim is oblivious to the mining activity that is being perpetrated by the hacker.

This type of attack has infected your device itself and is sometimes called a local attack.

Another way cryptojacking works is through an approach called the drive-by method. In this form, malicious threats have been embedded into a JavaScript code that is on a webpage. So, any user visiting such pages have their devices mining cryptocurrency for these hackers unknowingly.

Some websites have been open about how they could be using your device for mining activities in some cases. Most of these sites believe it is a fair transaction for them to use your device to mine for crypto assets while you have access to whatever free content they might on the site. An example could be a free gaming website that knows an average user would spend considerable time on their site. The site might use the device (laptop, PC, mobile phones, etc.) of their players to mine for cryptocurrencies while playing their games on the website.

However, immediately after such users close the tab or leaves the site, the device is no longer susceptible to hacking. This system has given way to situations where the victim’s device is still being continued to use to mine for crypto assets despite having left the site.

Examples of Cryptojacking Attacks

In 2018, a cybersecurity firm in Spain reported that a cryptojacking script, WannaMine, had become widespread in the world. According to the firm Panda, the hackers were mining Monero, one of the most popular privacy coins.

This digital asset was relatively easy to mine as it depended on CPUs and not GPUs or ASICS.

Another noteworthy attack was the one reported by the governments of Britain, the UK, and Canada. According to them, a cryptojacking attack took advantage of the text-to-speech software embedded in some of these governments’ sites. These hackers then inserted a malicious Coinhive script into the software, which allows them to mine monero using the site’s visitors’ browsers.

How to Detect and Prevent Cryptojacking

In all honesty, detecting a cryptojacking attack can be a Herculean task. It is almost impossible to spot as it is always hidden or presented as an essential activity for your device. And unsuspecting users tend to fall for this gimmick.

However, regardless of this, a device that has been cryptojacked would show the following signs:

  • Your device fan would begin to run faster than usual to prevent it from heating up. A cryptojacking script would ordinarily make your device work overtime, and as such, to meet up with this new load of works, your fan would step up to prevent any danger.
  • Your device would begin to feel much hotter than usual.
  • Your device begins to perform below its optimal best.

Other signs might include the battery of your device draining faster than usual or a high electricity bill.

To prevent this form of attack, there are some notable actions that one can carry out. Some of them are:

  • One can begin to use browser extensions that would block the cryptojacking scripts that abound on the internet.
  • Internet advertising is a common feature of the World Wide Web. And one thing about the web is that some of these scripts are embedded on these sites, so blocking these advertising sites could save one from the attackers.
  • We mentioned how drive-by crypto mining scripts are embedded in JavaScript. Another way of preventing cryptojacking would be to disable JavaScript when accessing the internet. This would help to protect the user against any such attack.


Cryptojacking in recent times has become widespread as hackers are getting more sophisticated in their attacks against unsuspecting internet users.

Accordingly, while most victims of these malicious attacks might not know that they are being used for the benefit of another, the wear and tear and the level of bills that come with the attack begin to weigh them down in little or no time.

Crypto mining can be laborious, time-consuming, and very expensive to run; through the use of cryptojacking softwares, the hacker can subvert this and still look for means to garner profits from unsuspecting victims.



What is a cryptojacking attack?

Cryptojacking attack is a cyberattack in which the computing system of a victim is used, without his consent, to mine for crypto assets like Bitcoin, Ethereum, etc.

Why is cryptojacking bad?

Victims of this attack do not know their systems are being used for this act. As such, they bear all wear and tear that occurs with their devices and every other expense that might be incurred.

What does a Bitcoin Miner virus do?

A Bitcoin miner virus attacks the system of a device to mine Bitcoin. The miner virus uses the computing power of the computer to mine Bitcoin on behalf of the hacker.

How do I know if my computer is used to mine cryptocurrency?

You really cannot easily know if your device is being used to mine cryptocurrency. But some of the telltale signs are

  1. Your device begins to work below its optimal best.
  2. The fan of your computing device works overtime so as to cool the device more often.
  3. Your device would begin to feel much hotter than usual.
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