500,000 PCs affected by crypto-currency mining malware

Over 500,000 computers around the world were affected in just 12 hours by a rapidly spreading cryptocurrency-mining malware.

But Microsoft encountered this activity and successfully blocked it to a large extent.

Dubbed Dofoil, aka Smoke Loader, the malware was found dropping a cryptocurrency miner program as payload on infected Windows computers that mines Electroneum coins, yet another cryptocurrency, for attackers using victims’ CPUs.

Windows Defender detected more than 80,000 instances of several variants of Dofoil that raised the alarm at Microsoft Windows Defender research department, and within the next 12 hours, over 400,000 instances were recorded.

Where did this come from?

The research team found that all these instances, rapidly spreading across Russia, Turkey, and Ukraine, were carrying a digital coin-mining payload, which masqueraded as a legitimate Windows binary to evade detection.

However, Microsoft did not mentioned how these instances were delivered to such a massive audience at the first place in this short period.

Dofoil uses a customized mining application that can mine different cryptocurrencies, but in this campaign, the malware was programmed to mine Electroneum coins only.

Researchers have stated that Dofoil trojan uses an old code injection technique called ‘process hollowing’ that that involves spawning a new instance of a legitimate process with a malicious one so that the second code runs instead of the original, tricking process monitoring tools and antivirus into believing that the original process is running.

To stay persistence on an infected system for a long time to mine Electroneum coins using stolen computer resources, Dofoil trojan modifies the Windows registry.

Dofoil also connects to a remote command and control (C&C) server hosted on decentralized Namecoin network infrastructure and listens for new commands, including the installation of additional malware.

Microsoft says behaviour monitoring and Artificial intelligence based machine learning techniques used by Windows Defender Antivirus have played an important role to detect and block this massive malware campaign.


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