Mining cryptocurrencies it can become very lucrative endeavor. The downside is that you usually need a lot of time and processing power to achieve decent profits.
However, some websites take advantage of their visitors and use the CPU of their PC or mobile phone without their consent to carry out this type of work. Easy money. Websites that "hijack" your PC. Yes friends. They exist, and today we are going to see how to detect them and prevent them from taking advantage of us.
How to detect if a website is using your computer's CPU to mine cryptocurrencies
Last week, while browsing the Internet on my desktop PC, I started to notice surprising slowness. Everything was slow, Windows Explorer was barely responsive, and pages and applications took a long time to open. Excessively low performance without any apparent justification.
Sure enough, after doing some research, I discovered the culprit: a web page that I had loaded in one of the various Chrome tabs was consuming 65% of my computer's CPU.
What method do web pages use to mine cryptocurrencies?
Not all cryptocurrencies require the same level of processing. Digital currencies like Monero or Dash are easier to mine, and they are not resource intensive. On the contrary, Bitcoin is much heavier and its impact on PC performance is much more noticeable.
Normally, websites tend to use Monero to "saber" its visitors, since its mining work attracts less attention, and logically, it is more difficult to detect.
The recruitment process is very simple. No malware of any kind is used to infect the computer. Simply runs through a JavaScript file to enable the mining, at the moment the visitor accesses the page.
Last year the cybersecurity company ESET released an interesting article with a list of websites that carry out this type of activity.
Signs that we are being victims of unintentional mining
- General slowness on the computer.
- Folders take longer than normal to open.
- Slowdown when browsing the Internet.
- Applications take time to respond.
The best way to check it, in any case, is open Task Manager (or the Activity Monitor if what we have is a Mac).
This is what happens to the CPU when a web page is using our equipment to mine cryptocurrenciesNormally the CPU consumption of the browser is 20% or less. If the consumption of the Internet browser is much higher - let's say 50 or 60 percent-, and also this consumption is maintained over time, it is very likely that a website is mining bitcoins or Monero from our PC.
How to prevent a web from mining bitcoins with the CPU of our PC
As the mining is taking place from the web page we are visiting, the easiest way to stop it is closing the malicious web tab. This will stop the mining script from working.
If closing the tab does not solve the problem, a window may be running "pop-under”. It is a window that opens just below the clock on the Windows taskbar, making it impossible to detect and close (at least by hand). To solve it we will have to open the Task Manager and close all browser instances From there.
Pop-unders are hidden under there and there is no way to close them using traditional methods.Another thing we can do is block the execution of JavaScript in the browser. This will prevent the mining functions from being executed. However, this has a rather negative side effect: a lot of pages use JavaScript to function for totally legitimate purposes. If we disable JavaScript, many pages will not load correctly.
For added protection, a mine blocker installed
There are several extensions for Chrome, Firefox, and Opera that can be used to block cryptocurrency mining scripts.
- No Coin (Chrome, Firefox, Opera)
- minerBlock (Chrome, Firefox, Opera)
- Anti Miner (Chrome)
- Coin-Hive Blocker (Chrome)
What these types of applications do is use blacklists of well-known mining scripts and websites. They work quite well and are one of the best ways to protect against these types of threats.
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