Microsoft collaborated with Japanese authorities, Health-ISAC and several cybersecurity companies to dismantle an expansive, seemingly disconnected ecosystem of Chinese-language cybercrime tools and services, the company announced Wednesday.

Since the start of the year, a vast collection of customized phishing kits developed and sold by Chinese-speaking threat actors — a cluster Microsoft tracks as Storm-2990 — have delivered more than 1 billion phishing emails and SMS messages to more than 75,000 organizations globally. More than three-quarters of those malicious messages targeted Microsoft customers, the company said.

Cybercriminals purchased the phishing kits, tools and infrastructure from an interconnected network Microsoft and Japanese authorities started investigating in early 2025. The kits were used to target individuals and organizations in healthcare, financial services, logistics and IT predominantly in the United States and Japan.

Microsoft said it and Health-ISAC, working with a federal court order, seized and redirected domains that powered the underlying infrastructure of these cybercrime tools and services known as YAM Store, CoGUI and Iron Man. 

The company said it also disabled more than 20,000 accounts connected to YAM Store and continues to disrupt the operation by removing infrastructure hosted on its services and blocking more than 100,000 domains used for impersonation and fraud.

“Most people have opened their messages to find a suspicious alert urgently telling them that a package cannot be delivered, a toll remains unpaid, a bank account needs attention, or a tax bill is overdue. The details may change, but the goal is the same: to get someone to click, share personal information, or pay,” Steven Masada, general counsel and general manager of Microsoft’s Digital Crimes Unit, wrote in a blog post.

“These messages are relentless,” he added. “Delete and block one, and another takes its place. Ignore them, and more will follow. Fall for one, and the floodgates open. What appears to be a simple scam message is often the visible end of a much larger transnational cybercriminal operation.”

The phishing kids included templates impersonating legitimate brands that cybercriminals used to facilitate high-volume campaigns. Researchers said similar infrastructure and overlapping activity suggested the tools shared development origins, code reuse or close collaboration among developers.

Microsoft said cybercriminals used the phishing kits to steal credentials, financial data and abuse the device code authentication process to obtain authentication tokens and access compromised accounts. Researchers said cybercriminals primarily used the tools for financial fraud, typically using stolen payment data to make fraudulent purchases of high-end goods or transactions on legitimate financial platforms. 

Resecurity, which aided the investigation, gained access to Iron Man’s infrastructure and found 2,360 phishing templates impersonating banks, retailers, healthcare providers, transportation authorities, police departments and government agencies across 130 countries. Cloudflare, Oracle, Proofpoint and TRM Labs also provided research and investigative support.

“What began with scam activity targeting people and organizations in Japan led investigators to an underground service economy supplying criminals around the world,” Masada wrote. 

“YAM Store, CoGUI and Iron Man are only part of that larger criminal network, but disrupting them makes it harder for criminals to obtain the accounts, tools and infrastructure they rely on,” he added. “The scam message is often the only part victims see. The businesses behind it are what make it possible.”

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Researchers said INC ransomware, one of the most active ransomware groups globally, has been the main attacker exploiting a pair of SonicWall zero-days soon after they were disclosed last month.

The prolific ransomware-as-a-service operation wasn’t the first group to exploit the flaws, which were actively exploited for three weeks before the vendor disclosed and patched the defects July 14, but it has been the most assertive and concerning group to target and chain both vulnerabilities together for full access.

“Since public disclosure, INC ransomware has emerged as the most commonly named threat actor actively weaponizing this vulnerability chain,” Brett Deroche, director of incident response at Rapid7, told CyberScoop. “While Inc is the name driving the post-disclosure wave, we can’t attribute the full body of exploitation to INC specifically.”

SonicWall did not respond to a request for comment.

The SonicWall vulnerabilities — CVE-2026-15409 and CVE-2026-15410 — are the latest in a series of security issues confronting the vendor’s customers, including actively exploited zero-days, previously disclosed defects, and an attack last year that allowed a state-sponsored threat group to steal the firewall configurations of every SonicWall customer. 

Just last week, Huntress researchers spotted an attack spree that compromised 30 SonicWall customers in less than two days. 

Ransomware groups have taken a special interest in SonicWall. Ten of the 17 SonicWall defects added to the Cybersecurity and Infrastructure Security Agency’s known exploited vulnerabilities (KEV) catalog since late 2021 are known to be used in ransomware campaigns.

INC ransomware, which has claimed nearly 900 victims across 71 countries since it was first discovered three years ago, is just the latest financially-motivated group to target SonicWall customers. 

Researchers haven’t determined how many organizations have been impacted by the latest SonicWall zero-days, including attacks linked to INC ransomware. 

“Attribution here isn’t a single clean answer. The earliest exploitation we observed, beginning June 22, traced back to common hosted infrastructure, though those attacks were largely unsuccessful,” Deroche said. 

“INC’s confirmed activity that we’ve observed came after public disclosure, using different infrastructure and moving from initial access to ransomware deployment in short order. That’s a meaningfully different operational tempo and skill level than what we saw pre-disclosure,” he added. 

Deroche said Rapid7 has successfully prevented data theft and encryption in the majority of recent cases, yet noted ransomware was deployed in at least one case the security vendor observed.

Yet, there could be other attacks outside the purview of Rapid7’s telemetry. INC ransomware has listed multiple new alleged victims on its data leak site, including organizations and government agencies in Australia, the United States, the United Arab Emirates, Colombia and Switzerland, Resecurity said in a blog post Saturday.

The company said it has aided several victims with incident response, and learned multiple victims received emails and phone calls from alleged hackers who pressured them to engage in negotiations.

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