Published by Global Banking & Finance Review®
Posted on July 23, 2025
2 min readLast updated: January 22, 2026
Add as preferred source on GoogleMicrosoft warns of ransomware linked to SharePoint server hacks, with over 400 victims including U.S. agencies, escalating cyber threats.
By Raphael Satter
WASHINGTON (Reuters) -A cyber-espionage campaign centered on vulnerable versions of Microsoft's server software now involves the deployment of ransomware, Microsoft said in a late Wednesday blog post.
In the post, citing "expanded analysis and threat intelligence," Microsoft said a group it dubs "Storm-2603" is using the vulnerability to seed the ransomware, which typically works by paralyzing victims' networks until a digital currency payment is made.
The disclosure marks a potential escalation in the campaign, which has already hit at least 400 victims, according to Netherlands-based cybersecurity firm Eye Security. Unlike typical state-backed hacker campaigns, which are aimed at stealing data, ransomware can cause widespread disruption depending on where it lands.
The figure of 400 victims represents a sharp rise from the 100 organizations cataloged over the weekend. Eye Security says the figure is likely an undercount.
"There are many more, because not all attack vectors have left artifacts that we could scan for," said Vaisha Bernard, the chief hacker for Eye Security, which was among the first organizations to flag the breaches.
The details of most of the victim organizations have not yet been fully disclosed, but on Wednesday a representative for the National Institutes of Health confirmed that one of the organization's servers had been compromised.
"Additional servers were isolated as a precaution," he said. The news of the compromise was first reported by the Washington Post.
Other outlets said the hacking campaign had breached an even broader range of U.S. agencies. NextGov, citing multiple people familiar with the matter, reported the Department of Homeland Security had been hit, along with more than five to 12 other agencies.
Politico, which cited two U.S. officials, said multiple agencies were believed to have been breached.
DHS' cyberdefense arm, CISA, did not immediately return a message seeking comment on the reports. Microsoft did not immediately return a message seeking further details on the ransomware angle of the hacking or the reported government victims.
The spy campaign began after Microsoft failed to fully patch a security hole in its SharePoint server software, kicking off a scramble to fix the vulnerability when it was discovered.
Microsoft and its tech rival, Google-owner Alphabet, have both said Chinese hackers are among those taking advantage of the flaw. Beijing has denied the claim.
(Reporting by Raphael Satter; Editing by Mark Porter and Christopher Cushing)
The campaign centers on vulnerable versions of Microsoft's server software and now involves the deployment of ransomware by a group called 'Storm-2603'.
At least 400 victims have been reported, a significant increase from the 100 organizations cataloged earlier.
A representative confirmed that one of their servers was compromised and additional servers were isolated as a precaution.
The Department of Homeland Security has been reported to have been breached, along with multiple other agencies.
Microsoft and Alphabet have indicated that Chinese hackers are among those taking advantage of the security flaw in their SharePoint server software.
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