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Beware .ics Files: Your Calendar is a Trap
16 Oct
Summary
- Spam emails use .ics attachments to trick users into giving up credentials.
- Attackers disguise malicious links within fake meeting details.
- Hundreds of thousands of phishing emails target over 40,000 organizations.
Phishing campaigns are now leveraging .ics attachments, commonly used for calendar invites, to steal Microsoft 365 credentials. These malicious emails bypass standard filters, delivering fake meeting details, QR codes, or payment notifications directly to users' inboxes. Upon opening or accepting the invite, the fraudulent content appears as a legitimate appointment.
While no vulnerabilities are exploited, the event description or embedded links can redirect victims to spoofed sign-in pages. Researchers have observed a significant surge in these attacks since September 25, 2026, with hundreds of thousands of unique phishing emails detected. The activity is accelerating, growing from thousands of emails monthly to over 740,000 in the first two weeks of October.
