Threat actor links to China
Microsoft has revealed that a financially motivated hacker linked to China, called Storm-1175 has installed an earlier undocumented ransomware strain known as StormEncryptor. Storm-1175 is believed to exploit a critical flaw in a cybersecurity supply-chain campaign where threat actors can install custom ransomware throughout large list of target networks.
Storm-1175 began installing a new ransomware strain, Microsoft Threat Intelligence warned this week. Threat actors earlier deployed Medusa ransomware to take money from finance organizations, healthcare providers, and professional services in the US, Australia, and Britain.
About the attack
In April 2026, the threat actors operated “high-velocity ransomware campaigns,” abusing both recently revealed zero-day exploits and flaws, “in some cases a full week before public vulnerability disclosure.” Microsoft warned it had observed the gang transition from initial access to full encryption in less than 24 hours.
In the recent campaign, according to Microsoft, the group may be exploiting CVE-2026-18577- a flaw in the N-central, a remote monitoring and management (RMM) console used by various service providers to supervise client endpoints.
Attack tactic
Microsoft has not officially verified the access vector, but found that StormEncryptor installations started the same day the bug was revealed. The flaw allows threat actors “unauthenticated, ‘god-mode’ access,” warned cybersecurity firm Huntress.
The flaw permits threat actors with no credentials to get full administrative command over the N-central server to handle clients’ machines remotely’. The single hacked server becomes an entry point to every endpoint it commands. A single provider can offer dozens of ransomware incidents throughout its entire client base.
A similar supply-chain attack on an RMM tool in 2021 from software provider Kaseya permitted Revil ransomware group to hack 60 of Kaseya’s direct consumers before attacking 1,500 downstream organizations.
In 2024, another supply chain attack on an RMM, affected ConnectWise’s ScreenConnect product. It resulted in various downstream ransomware campaigns. According to Microsoft, Storm-1175 was amid the various gangs attacking ScreenConnect during that phase.
Estimates of impacted firms have not been confirmed. Parent company N-central’s N-able software company said it reached out to a limited number of impacted customers. Huntress has acknowledged few of its own consumers were affected and posted a timeline demonstrating how the threat actors travelled across downstream hosts in two cases, but Huntress did not verify the number of downstream organizations impacted from the ransomware attacks.
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