Calendar-based phishing jumps 33,000% since May, researchers say

Sublime researchers report a sharp rise in ICS phishing: from May to September 2026, attacks via calendar invitations grew by about 33,000%. Attackers send invitations from free services like Gmail, bypassing filters, and lead victims to install RMM tools such as ScreenConnect.

• ICS phishing growth from May to September estimated at ~33,000%
• August growth was 1216%, first half of September was 1426%
• Attacks bypass filters by using legitimate services like Gmail
• Victims are led to install RMM tool ScreenConnect for device takeover