Threat actors leverage tax season to deploy tax-themed phishing campaigns
As Tax Day approaches in the United States on April 15, Microsoft has detected several tax-themed phishing campaigns employing various tactics.
Research
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Malvertising campaign leads to info stealers hosted on GitHub
Microsoft detected a large-scale malvertising campaign in early December 2024 that impacted nearly one million devices globally. -
Silk Typhoon targeting IT supply chain
Silk Typhoon is a Chinese state actor focused on espionage campaigns targeting a wide range of industries in the US and throughout the world. -
Frequent freeloader part II: Russian actor Secret Blizzard using tools of other groups to attack Ukraine
Since January 2024, Microsoft has observed Secret Blizzard using the tools or infrastructure of other threat groups to attack targets in Ukraine and download its custom backdoors Tavdig and KazuarV2. Retain Microsoft Security Experts
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Midnight Blizzard conducts large-scale spear-phishing campaign using RDP files
Since October 22, 2024, Microsoft Threat Intelligence has observed Russian threat actor Midnight Blizzard sending a series of highly targeted spear-phishing emails to individuals in government, academia, defense, non-governmental organizations, and other sectors. -
Storm-0501: Ransomware attacks expanding to hybrid cloud environments
August 27, 2025 update: Storm-0501 has continuously evolved to achieve sharpened focus on cloud-based TTPs as their primary objective shifted from deploying on-premises endpoint ransomware to using cloud-based ransomware tactics. -
Ransomware operators exploit ESXi hypervisor vulnerability for mass encryption
Microsoft Security researchers have observed a vulnerability used by various ransomware operators to get full administrative access to domain-joined ESXi hypervisors and encrypt the virtual machines running on them. -
Moonstone Sleet emerges as new North Korean threat actor with new bag of tricks
Microsoft has identified a new North Korean threat actor, now tracked as Moonstone Sleet (formerly Storm-1789), that combines many tried-and-true techniques used by other North Korean threat actors, as well as unique attack methodologies to target companies for its financial and cyberespionage objectives. Modernize your Security Operations Center with Microsoft Sentinel
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Analyzing Forest Blizzard’s custom post-compromise tool for exploiting CVE-2022-38028 to obtain credentials
Since 2019, Forest Blizzard has used a custom post-compromise tool to exploit a vulnerability in the Windows Print Spooler service that allows elevated permissions. -
Octo Tempest crosses boundaries to facilitate extortion, encryption, and destruction
Microsoft has been tracking activity related to the financially motivated threat actor Octo Tempest, whose evolving campaigns represent a growing concern for many organizations across multiple industries. -
Multiple North Korean threat actors exploiting the TeamCity CVE-2023-42793 vulnerability
Since early October 2023, Microsoft has observed North Korean nation-state threat actors Diamond Sleet and Onyx Sleet exploiting the Jet Brains TeamCity CVE-2023-42793 remote-code execution vulnerability.
