Brazil Hit by Banking Trojan Spread via WhatsApp Worm and RelayNFC NFC Relay Fraud
Dec 03, 2025
Banking Security / Malware
The threat actor known as Water Saci is actively evolving its tactics, switching to a sophisticated, highly layered infection chain that uses HTML Application (HTA) files and PDFs to propagate via WhatsApp a worm that deploys a banking trojan in attacks targeting users in Brazil. The latest wave is characterized by the attackers shifting from PowerShell to a Python-based variant that spreads the malware in a worm-like manner over WhatsApp Web. "Their new multi-format attack chain and possible use of artificial intelligence (AI) to convert propagation scripts from PowerShell to Python exemplifies a layered approach that has enabled Water Saci to bypass conventional security controls, exploit user trust across multiple channels, and ramp up their infection rates," Trend Micro researchers Jeffrey Francis Bonaobra, Sarah Pearl Camiling, Joe Soares, Byron Gelera, Ian Kenefick, and Emmanuel Panopio said . In these attacks, users receive messages from trusted contacts on WhatsA...