Browser Miner Virus - How to Detect and Remove

Browser Miner Virus – How to Detect and Remove

Statistics from November this year revealed that 2,531 of the top 3 million websites are running the Coinhive miner, which amounts to 1 in 1,000 websites. To no one’s surprise, BitTorrent websites have been the main perpetrators. But they are not the only ones, as many other, often unexpected, websites are using users’ computer resources to mine for cryptocurrencies. Since the so-called browser miner virus is an emerging threat leveraging PC’s resources for crypto mining, users definitely need to know how to protect themselves from it. This article aims to help remove a browser miner virus from a computer.

Threat Summary

NameBrowser miner virus
TypeCryptocurrency Miner
Short DescriptionA browser miner virus may exploit the CPU, GPU and other PC resources for the purpose of mining for various cryptocurrencies.
SymptomsIncreased CPU and GPU usage and overheating.
Distribution MethodSpam Emails, Email Attachments, Executable files, Hacked Websites
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Browser Miner Virus – Distribution Techniques

This type of threat is not entirely new to the threat landscape but it’s the first time researchers witness browser miner attacks at such a scale. Even though the exact distribution method of this threat is not yet known, researchers consider that the massively deployed methods for malware distribution are valid here as well. What does this mean?

A browser miner virus could be spread in the wild with the help of automatically generated email messages. This is an easy way to send the virus to as many victims as possible. The virus maybe attached to the email, or it could be present in the form of a script. The good news here is that email services are typically prepared to detect the signatures of the virus, and the messages may not reach the inbox if they were timely labeled as spam.

Nonetheless, this is not the only distribution form. The browser miner virus may be distributed through hyperlinks that are inserted in the email message itself. To lure the potential victim into clicking on it, the link may be disguised as something familiar to the user. Such redirects may send the user directly to hacked websites leveraged for cryptocurrency mining.

Other methods used for the distribution of browser miner viruses include the use of malicious websites and download (p2p) networks. Such websites are often used to spread malware across users worldwide, and the browser miner virus is not an exclusion of this well-known practice. The virus may even be hiding in infected documents, like spreadsheets, rich text documents, and databases. These could be altered to trigger the virus when the built-in scripts are activated. What usually happens in this case is that the user opens a notification prompting them to run macros, or scripts. Such an action will definitely lead to an infection with a browser miner virus.

Interestingly, browser hijackers may also be deployed in the distribution of miners – in the form of add-ons that are available for most browsers available to users, the most popular ones (Firefox, Chrome, Explorer, Edge, etc.) inclusive. If the user is tricked into installing such a malicious add-on (browser extension), he may end up being redirected to a hacked site leveraged for mining. However, according to the configuration of the hijacker, it can also perform other suspicious activities, like obtaining user login credentials, history, and similar.

Browser Miner Virus – Purpose, Capabilities, Deployment

It’s only logical to ask why this type of virus was created in the first place. The sole purpose of such a miner is to exploit the PC resources of unsuspecting users. These resources could be either or both the CPU and GPU of the system, depending on the cryptocurrency that the virus is mining for.

Another reason is that it is quite easy to start such a mining campaign. There is a ton of web services that can generate automatically compatible JavaScript code that will later be used in the mining operation. These services are prepared and they can support a variety of cryptocurrencies – like Bitcoin, Monero and Ethereum, among many others. These services can even provide tutorials to new beginners to help them initiate the mining operations. How is the money transferred? There may be some other options in combination with the unique wallet address. This is where the “crypto money” is going. In addition, CMS platforms can even provide plugins that make the whole process of code implementation quite easier.

Browser Miner Virus – Behavior and Consequences

Most browser miner virus types share an average behavioral pattern which leads to several outcomes for the user. One of these outcomes is the cross-browser contamination. What does this mean? Simply said, cross-browser contamination means that each subsequent browser window will escalate the pressure on the hardware resources and will divide them to several miner processes simultaneously. This leads to a problem known as resources allocation. This issue affects the whole operating system, be it Windows, Mac OS X, or Gnu/Linux. Unfortunately, there are miners available for each of these operating systems. As a result, the processor, memory and graphics card of a machine can be affected.

Moreover, there are two types of the browser miner virus, outlined as stand-alone miners and malware modules. As the name suggests, the second type is far more dangerous, compared to the stand-alone miners which are basically basic types. If the miner is deployed through malware module, it means that it has been implemented in ransomware, like an addition to the original components. This means that the system will be affected by both the ransomware and the miner. In order to avoid such bad infections, users need to think of their protection in advance.

Users should also keep in mind that, like every other virus out there, browser miner viruses are also evolving. Advanced JavaScript code may be used to allow the miner process to continue “working” even after the browser window is closed.

This is known as drive-by cryptomining, or cryptojacking. In a recent infection case researchers stumbled upon a technique that enabled hackers to keep mining for Monero even after the browser window was closed. The research was focused on the Chrome browser but other browsers may have been affected as well, with different outcomes for each browser.

What happens after a user visits a website, which is silently loading the mining code is that the CPU activity is increasing but it is not maxing out. After the user leaves the particular site via closing the Chrome window, his machine’s CPU activity remains higher than usual. This is a sign that the cryptomining process is not resumed with the closing of the browser.

Browser Miner Virus – Removal

There are different ways to deal with a browser miner virus depending on its type and capabilities. The more sophisticated the miner is, as in the recent cases of drive-by cryptomining, the more challenging it would be to deal with it.

If the miner is a basic one, the user may install a specific extension according to his browser that would stop the mining in the web browser. There is also the option to manually block domains that are associated with cryptocurrency mining.

However, if the system is affected by malware or ransomware that was equipped with a browser miner virus, then it is advisable to use a proper anti-malware solution to deal with all of the infections.


Milena Dimitrova

An inspired writer and content manager who has been with SensorsTechForum for 4 years. Enjoys ‘Mr. Robot’ and fears ‘1984’. Focused on user privacy and malware development, she strongly believes in a world where cybersecurity plays a central role. If common sense makes no sense, she will be there to take notes. Those notes may later turn into articles! Follow Milena @Milenyim

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