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In a sign that threat actors continuously shift tactics and update their defensive measures, the operators of the SolarMarker information stealer and backdoor have been found leveraging stealthy Windows Registry tricks to establish long-term persistence on compromised systems.

Cybersecurity firm Sophos, which spotted the new behavior, said that the remote access implants are still being detected on targeted networks despite the campaign witnessing a decline in November 2021.

Boasting of information harvesting and backdoor capabilities, the .NET-based malware has been linked to at least three different attack waves in 2021. The first set, reported in April, took advantage of search engine poisoning techniques to trick business professionals into visiting sketchy Google sites that installed SolarMarker on the victim’s machines.

Then in August, the malware was observed targeting healthcare and education sectors with the goal of gathering credentials and sensitive information. Subsequent infection chains documented by Morphisec in September 2021 highlighted the use of MSI installers to ensure the delivery of the malware.

The SolarMarker modus operandi commences with redirecting victims to decoy sites that drop the MSI installer payloads, which, while executing seemingly legitimate install programs such as Adobe Acrobat Pro DC, Wondershare PDFelement, or Nitro Pro, also launches a PowerShell script to deploy the malware.

images from Hacker News