AI-Enhanced Python Malware Targets Brazilian Financial Institutions via WhatsApp
A threat campaign known as Water Saci has escalated its attacks on Brazilian financial institutions and cryptocurrency exchanges by deploying a new Python-based malware variant. This campaign leverages artificial intelligence (AI) to convert previous PowerShell propagation scripts into Python, resulting in broader browser compatibility, improved error handling, and faster automation of malware delivery through WhatsApp Web. The attackers use a highly layered attack chain involving multiple file formats such as HTA files, ZIP archives, and PDFs to evade detection and complicate analysis, with the ultimate goal of stealing sensitive data and monitoring user activity on compromised machines.
The campaign primarily targets enterprise users of WhatsApp in Brazil, exploiting social engineering tactics to deliver malicious payloads through convincing messages from trusted contacts. Researchers warn that the use of AI-driven code conversion and multi-format delivery methods marks a significant evolution in the threat landscape, making these attacks more sophisticated and harder to detect. While the campaign is currently concentrated in Brazil, there is concern it could expand to other Latin American countries as the techniques continue to evolve.
Timeline
Dec 2, 2025
Trend Micro publicly discloses Water Saci campaign and mitigations
Trend Micro published research detailing the Water Saci campaign, its AI-enhanced Python variant, and its WhatsApp worm propagation in Brazil. The company also recommended mitigations such as disabling WhatsApp auto-downloads, restricting file transfers, and strengthening endpoint and application controls.
Dec 2, 2025
Researchers link Water Saci malware to Casbaneiro/Metamorfo lineage
Analysis of the banking trojan and delivery chain found strong structural ties to the Casbaneiro/Metamorfo malware family. The malware was described as capable of credential theft, banking activity fingerprinting, registry-based persistence, process hollowing, and IMAP-based command-and-control updates.
Dec 2, 2025
Campaign evolves from PowerShell to Python-based propagation
Researchers reported that Water Saci updated its malware propagation from a PowerShell-based approach to a Python variant, improving browser compatibility, automation, and evasion. The change was assessed as likely aided by AI or large language model tooling used to convert and enhance the codebase.
Dec 2, 2025
Water Saci operates WhatsApp-based banking trojan campaign in Brazil
A threat campaign attributed to Water Saci targeted Brazilian banking and cryptocurrency users using WhatsApp as a self-propagating infection channel. The operation used layered payloads including HTA, ZIP, PDF, MSI, and AutoIt components to deliver a banking trojan with persistence, anti-analysis, and remote-control capabilities.
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