chaos ransomware

Microsoft Teams Vishing Ransomware Hits in 17 Hours

By Editorial Team | August 4, 2026

A Microsoft Teams vishing ransomware campaign, STAC4749, breached dozens of firms via fake IT-helpdesk calls, encrypting networks within 17 hours.

A Microsoft Teams vishing ransomware campaign has hit dozens of North American organizations since February 2026, using two-minute fake IT-helpdesk phone calls to gain a foothold that, in the fastest confirmed case, ended in full Chaos ransomware encryption within 17 hours of first contact. What Happened Security vendor Sophos tracked the campaign to a financially…