Qualys has developed a free extension for Google Chrome to protect browsers from cryptojacking attacks, Dark Reading has learned.

The new BrowserCheck CoinBlocker Extension uses both domain blacklists for cryptocurrency mining sites as well as heuristics features to detect unknown cryptojacking attack types. Qualys will officially roll out the plugin on Wed., July 25, but it’s already available on the Google Chrome Web Store.

Cryptojacking attacks often occur when an attacker infects a website with JavaScript, and an unsuspecting user visitor to the site unknowingly downloads that malicious code via a browser. The victim’s machine is then used to mine cryptocurrency, which the attacker pockets. The process can eat up more than 70% of a machine’s CPU, according to Qualys researchers.

Ankur Tyagi, senior malware research engineer at Qualys and one of the creators of the tool, says while there are other existing Chrome extensions for cryptojacking protection, most rely soley on a blacklist of IP addresses and not heuristics. Qualys’ BrowserCheck CoinBlocker Extension also was built to detect the popular CryptoNight family of cryptomining software, Tyagi says, the most pervasive of which is Monero.

Among the other coin types under the CryptoNight umbrella are ByteCoin, Digital Note, AEON, Loki, and BitTube. Tyagi says the heuristics feature in the plugin can spot patterns that indicate cryptomining algorithm activity.

“Attackers are trying to create JavaScript-based attacks that can be launched on clients that visit” crypto malware-infected sites, he says.

BrowserCheck CoinBlocker works like this: When a user browses a website, the plugin checks for the telltale malicious JavaScript. If it detects it, it stops the browser from downloading the JavaScript and also blocks the mining site. Qualys also plans to later roll out versions of the plugin for the Firefox, Safari, and Internet Explorer browsers.

Google has been well aware of cryptocurrency mining abuse. In April, Google removed and banned cryptocurrency mining extensions in the Chrome Web Store after 90% of these apps violated its policy of properly informing users of the the apps’ purpose. 

The worldwide overall cryptocurrency market capitalization hit $270 billion this month, according to Qualys, demonstrating just how lucrative it is for abuse. Meantime, malicious coin-mining samples increased by 629% in the first quarter of this year, according to McAfee, from 40,000 samples in Q4 2017 to 2.9 million in Q1 2018.

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Kelly Jackson Higgins is Executive Editor at DarkReading.com. She is an award-winning veteran technology and business journalist with more than two decades of experience in reporting and editing for various publications, including Network Computing, Secure Enterprise … View Full Bio