Too often, when an individual needs to edit a text document or an image in a hurry, the easy option is to download the first openly distributed or even cracked application they can find.

However, although the program appears to work normally, they notice that their PC appears to be running more slowly than usual, their electricity bill spikes significantly that month.

Easy Money

"If this sounds familiar, it's likely that you've got a miner," says Kaspersky Lab. "Along with a spike in the crypto-currency market, malicious mining software has been actively deployed by criminals in order to make easy money and became a major trend in 2017."

According to the company who predicted this trend in 2016, its researchers spotted a comeback of mining software amid the growing popularity of the crypto-currency Zcash.

A year later, and miners are everywhere, the company adds. "By the end of 2017, the number of affected users would exceed two million."

Alexander Kolesnikov, malware analyst at Kaspersky Lab, says although mining software is not considered strictly malicious, it decreases the device's system performance, which inevitably affects the user experience, and it increases their power usage.

"As a result, the use of seemingly harmless pirated software leads to the victim - at their own expense - augmenting someone else's wallet. We advise users to remain vigilant and use legal software to avoid such malicious handouts," says Kolesnikov.

According to him, cyber criminals are employing a variety of tools and techniques, such as social engineering campaigns involving adware or cracked software, in order to affect as many computers as possible.

Kaspersky Lab researchers have recently identified a number of Web sites, created using one standard design, which have been offering users free, pirated software such as popular computer programs and applications.

No free lunch

Kolesnikov says to be wary when someone offers something for nothing. The aim of these Web sites is to spread a particular mining software, and as a result, free applications are putting users at risk.

"Along with the downloaded archive, users received a miner which was automatically installed together with the desired software. After this, the miner started silently operating on the victim's PC, using its power to generate crypto-currency which goes directly back to the criminals."

He says the installation archive also included text files containing initialisation information - an address of the criminals' wallet, as well as a mining pool - a special server to unite several participants and distribute a mining task among their computers. "In exchange, participants receive their share of crypto-currency. Due to the fact that mining Bitcoins and other crypto-currencies is currently a very resource-heavy and time-consuming operation, the pools provide increased efficiency and higher speeds of crypto-currency production."

Avoiding the trap

To avoid having minders unwittingly downloaded on your PC, Kaspersky Lab recommends that users only download legal software from proven sources. In addition, the company advises to never click on unknown Web sites or suspicious banners and ads, and to install a reliable security solution that protects from all possible threats including malicious mining software.