Brazil Faces 2025 Banking Trojan Crisis Spread via WhatsApp and NFC Relay Fraud
In late 2025, Brazil was struck by a sophisticated banking trojan campaign perpetrated by the threat actor Water Saci. Leveraging WhatsApp as a wormable transmission channel, attackers delivered highly obfuscated HTA and PDF payloads to users. Once opened, these files initiated a new Python-based trojan variant, enabling credential theft and fraudulent banking transactions. The attack chain also included NFC relay tactics (RelayNFC), amplifying transactional fraud by hijacking contactless payment operations. The campaign evaded detection using advanced scripting and lateral propagation, causing financial and reputational damage within the Brazilian financial sector. This incident marks a significant escalation in multichannel malware delivery, combining social engineering, banking trojans, and NFC payment interception. It underscores the converging risk between consumer messaging apps and new payment technologies, highlighting the urgency for layered east-west and egress network protection.
Kill Chain