If you are a victim of cryptojacking, you may not realize it. Most cryptojacking software is designed to remain hidden from the user, but this does not mean that it is not noticed. This theft of your computing resources slows down other processes, increases your electricity bill and shortens the life of the device. Depending on how subtle the attack is, certain red flags can be observed. If your PC or Mac slows down or the fan runs more times than normal, you have reason to suspect that it is cryptojacking.

The motivation for cryptojacking is simple: money. Cryptocurrency mining can be very profitable, but becoming profitable is almost impossible without the means to cover large costs. For someone who has limited resources and questionable morale, cryptojacking is an affordable and effective way to mine valuable coins.

How does cryptojacking work?

One of the methods works like classic malware. The user clicks on a malicious link in an email that uploads cryptocurrency mining code directly to the computer. Once the computer is infected, the cryptojacker begins to work around the clock to extract cryptocurrencies, staying hidden in the background. Since it resides on the PC, it is local, which means that it is a persistent threat that has infected the computer itself.

An alternative approach to cryptojacking is sometimes called fortuitous cryptocurrency mining. Like malvertising exploits , the scheme involves embedding a snippet of JavaScript code into a web page. Then, it performs cryptocurrency mining on the machines of the users who visit that page.

'Random cryptocurrency mining can infect even Android mobile devices.'

In the early cases of fortuitous cryptocurrency mining, web publishers took to the bitcoin rush in an attempt to supplement their revenue and monetize their site traffic, openly asking visitors for permission to mine cryptocurrency while on their sites. They posed it as a fair trade: you get free content while they use your computer for mining. If you are, for example, on a gaming site, you will probably stay on the page for some time while the JavaScript code extracts coins.

The more malicious versions of fortuitous cryptocurrency mining don't bother to ask for permission and keep running long after the user leaves the initial site. This is a common technique of dubious site owners or hackers who have compromised legitimate sites. Users have no idea that the site they visited has used their computer to mine cryptocurrencies. The code uses minimal enough system resources to be inconspicuous.

Random Cryptocurrency development can infect even Android mobile devices. It works with the same methods that are used for desktop computers. Some attacks take place through a Trojan hidden in a downloaded application. Or, users' phones can be redirected to an infected site that leaves behind a persistent hidden window.

You might be wondering why your phone has relatively less processing power. When these attacks occur en masse, the largest number of smartphones constitutes a collective force worthy of the attention of cryptojackers.

Some computer security professionals point out that, unlike many other types of malware, cryptojacking scripts do not damage computer or victim data. But the theft of CPU resources has consequences. Certainly, the decrease in computer performance can be just a bummer for an individual user. But in large organizations that have suffered from cryptojacking in many systems, it translates into real costs. IT department labor and electricity costs, as well as missed opportunities, are just some of the consequences of what happens when an organization is affected by fortuitous cryptojacking.

How prevalent is cryptojacking?

Cryptojacking is relatively new, but it is already one of the most common internet threats. In a recent Malwarebytes blog , our team at Intel found that malicious cryptocurrency mining (another name for cryptojacking) has been the most frequently encountered malware attack since September 2017. The following month, in an article published in October 2017 , Fortune suggested that cryptojacking is the biggest security threat in the digital world. Most recently, we have seen a 4000% increase in Android cryptojacking malware detections during the first quarter of 2018.

What's more, cryptojackers aim higher and higher and invade increasingly powerful hardware. An example is an incident in which criminals were cryptojacking from the operational Cryptocurrency technology network of the control system of a European public water distribution service and that degraded the operator's ability to manage the plant of that public service. In another case mentioned in the same report, a group of Russian scientists allegedly used the supercomputer at their nuclear warhead research and construction center to mine bitcoins.