Home Security New cryptocurrency miner malware infects Windows systems

New cryptocurrency miner malware infects Windows systems

Researchers at security firm Trend Micro say they have found a new cryptocurrency miner that operates as fileless malware, attacking Windows systems by using the EternalBlue exploit that powered the WannaCry ransomware in May.

In a blog post that detailed the characteristics of the malware and the way in which it gained access to a system, Trend Micro said it had been affecting the Asia Pacific region in July.

The major countries affected were Japan, Indonesia, Taiwan, Thailand and India; other countries in the region were only marginally affected.

Fileless malware exists only in the memory of an infected system making detection much more difficult.

Trend Micro said the malware uses Windows Management Instrumentation, a core component of Windows that is used for daily management tasks, as its filess persistence mechanism.

wmi1

Distribution of the new malware infections from July to August 2017.

To enter a system, the EternalBlue vulnerability was used. This exploit was developed by the NSA but leaked on the Web by a group known as Shadow Brokers in April. 

Apart from being used in WannaCry, it was also used in a mass ransomware outbreak — known variously as Petya (ransomware that already existed at the time), NotPetya, Nyetya, ExPetr and GoldenEye — that broke out in Europe in June and spread to other regions.

Trend Micro said the new malware was inserted as a backdoor on a Windows system which then installed various WMI scripts. These scripts then connected to the attacker's command and control servers to obtain instructions and download the cryptocurrency miner malware.

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The infection flow of the new cryptocurrency miner malware.

The company advised systems admins to restrict and disable WMI as needed to prevent this malware from infecting a system.

"Not all machines require the WMI service. If a machine does not need access to WMI, disable it to eliminate the risk," Trend Micro said. "Microsoft provides a quick guide on how to stop WMI service completely. Microsoft also provides a tool that can trace WMI activity. SMBv1 can also be disabled to reduce the risk to users."

It also pointed out that the entry point for this malware was EternalBlue, for which a patch had been available since March 2017. 

"However, there are still a lot of machines exposed to this vulnerability. Ensuring that the operating system, software, and other applications are updated with the latest patches deters threats from using security gaps as their doorways into systems and networks," Trend Micro said.

Graphics: courtesy Trend Micro

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Sam Varghese

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A professional journalist with decades of experience, Sam for nine years used DOS and then Windows, which led him to start experimenting with GNU/Linux in 1998. Since then he has written widely about the use of both free and open source software, and the people behind the code. His personal blog is titled Irregular Expression.