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Microsoft has released a blog post on possible Master Boot Record (MBR) Wiper activity targeting Ukrainian organizations, including Ukrainian government agencies. According to Microsoft, powering down the victim device executes the malware, which overwrites the MBR with a ransom note; however, the ransom note is a ruse because the malware actually destroys the MBR and the targeted files.
CERT Bulgaria recommends network defenders review the Microsoft blog for tactics, techniques, and procedures, as well as indicators of compromise related to this activity. CISA additionally recommends network defenders review recent Cybersecurity Advisories and the CISA Insights, Preparing For and Mitigating Potential Cyber Threats.

https://www.microsoft.com/security/blog/2022/01/15/destructive-malware-targeting-ukrainian-organizations/

https://www.cisa.gov/uscert/ncas/alerts

https://www.cisa.gov/publication/preparing-and-mitigating-potential-cyber-threats