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Cryptocurrency Mining Attacks Hitting Browsers Show Big Drop

The recent shut down of Coinhive has caused Malwarebytes to see far fewer attempts to mine cryptocurrencies over people's internet browsing sessions. "We went from tens of millions of blocks to an estimated two million per day,' said a company researcher.

 & Michael Kan Principal Reporter

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The chances of your internet browser getting hit with a sneaky cryptocurrency miner have apparently tanked.

On Thursday, the antivirus provider Malwarebytes reported that cryptomining-based attacks on consumers have largely become extinct, dropping by 79 percent from a year ago. A big reason why is because a top cryptocurrency miner provider, Coinhive, shut down in early March, it said.

Coinhive's miner worked via a computer script that anyone could install over a website. If your browser encountered the script, the miner would siphon away your PC's processing power to generate a virtual currency called Monero. In response, many antivirus providers began blocking Coinhive's miner from running over web browsers.

Bitcoin mining generic

However, Malwarebytes said its own antivirus product is no longer blocking as many cryptocurrency mining attempts as it used to. "We went from tens of millions of blocks to an estimated two million per day," said company researcher Jerome Segura in an email.

Coinhive was started back in 2017 and quickly gained a notorious reputation as a tool for hackers to generate money. To do so, the hackers secretly placed Coinhive's mining script into legitimate websites and third-party browser extensions they had managed to break into.

But in February 2019, Coinhive announced it was shutting down, citing the slumping cryptocurrency market and difficulties with mining Monero following a "hard fork" with the currency. A single Monero coin is now worth $62, down from the $400 value it reached back in Jan. 2018.

Nevertheless, Coinhive inspired some copycat services. "In-browser mining has decreased overall, but there are some contenders such as CryptoLoot and CoinIMP," Segura added. "The big difference though is that the vast majority of sites that are loading those miners are torrent portals, or file-hosting services, as opposed to compromised websites like we used to see in the past."

Cryptojacking Symantec

Credit: Symantec

Antivirus providers Symantec and McAfee have also noticed a drop in cryptocurrency mining attacks. "However the shutdown of Coinhive is not necessarily the driver," McAfee researcher Charles McFarland told PCMag in an email. "Issues stemming from the popularity of Monero, and declining mining profitability in general have likely played a much larger role in the decline of attacks."

"For example, Monero is battling custom, specialized miners taking up a large portion of the network and have forked their network in response," he added. "The specialized miners leave smaller miners, such as browsers, little room to profit."

A separate security firm, Check Point, has said that cryptocurrency miners still lead overall as the top malware threat with Coinhive alternative CryptoLoot ranking No. 1 on the list.

"Despite its closure, the Coinhive JavaScript code is still in place on many websites. No mining is taking place, but if the value of Monero increases significantly, it is possible that Coinhive may come back to life," Check Point said in a blog post.

Businesses also need to be on guard against unauthorized mining. Check Point has seen cases where cryptocurrency miners were found installed on cloud servers used by corporations. Due to the mining, which can sap computing resources, the businesses were forced to pay "hundreds of thousands of dollars" to the cloud server providers, Check Point said.

About Our Expert

Michael Kan

Michael Kan

Principal Reporter

My Experience

I've been a journalist for over 15 years. I got my start as a schools and cities reporter in Kansas City and joined PCMag in 2017, where I cover satellite internet services, cybersecurity, PC hardware, and more. I'm currently based in San Francisco, but previously spent over five years in China, covering the country's technology sector.

Since 2020, I've covered the launch and explosive growth of SpaceX's Starlink satellite internet service, writing 600+ stories on availability and feature launches, but also the regulatory battles over the expansion of satellite constellations, fights with rival providers like AST SpaceMobile and Amazon, and the effort to expand into satellite-based mobile service. I've combed through FCC filings for the latest news and driven to remote corners of California to test Starlink's cellular service.

I also cover cyber threats, from ransomware gangs to the emergence of AI-based malware. In 2024 and 2025, the FTC forced Avast to pay consumers $16.5 million for secretly harvesting and selling their personal information to third-party clients, as revealed in my joint investigation with Motherboard.

I also cover the PC graphics card market. Pandemic-era shortages led me to camp out in front of a Best Buy to get an RTX 3000. I'm now following how the AI-driven memory shortage is impacting the entire consumer electronics market. I'm always eager to learn more, so please jump in the comments with feedback and send me tips.

The Best Tech I've Had:

  • My first video game console: a Nintendo Famicom
  • I loved my Sega Saturn despite PlayStation's popularity.
  • The iPod Video I received as a gift in college
  • Xbox 360 FTW
  • The Galaxy Nexus was the first smartphone I was proud to own.
  • The PC desktop I built in 2013, which still works to this day.

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