A Python-based Malware-as-a-Service builder enables operators to generate customized Windows infostealer executables. The system comprises a builder component and an embedded payload, using Nuitka or PyInstaller compilation to evade detection. The builder features automatic dependency installation, webhook configuration with XOR and Base64 encoding, and multiple compilation backends. The payload targets Chromium and Firefox browsers, extracting credentials, cookies, and credit card data. It harvests Wi-Fi passwords, Discord tokens, and Roblox session cookies while employing anti-analysis techniques including debugger detection, VM process blacklisting, disk size checks, and timing evasion. Persistence is established through registry Run keys and scheduled tasks. All stolen data is packaged into in-memory ZIP archives and exfiltrated via attacker-controlled webhooks, following a scalable affiliate model.
An attacker registered the unscoped 'tanstack' name on npm and published four malicious versions (2.0.4-2.0.7) within 27 minutes on April 29, 2026. These packages contained postinstall hooks that automatically exfiltrated environment files containing sensitive credentials when developers ran npm install. The attacker exploited name confusion with the legitimate @tanstack organization, which publishes widely-used JavaScript libraries. The malicious code targeted .env files, stealing AWS keys, API tokens, database credentials, and OAuth secrets by sending them to an attacker-controlled Svix webhook endpoint. Version 2.0.6 was particularly dangerous, sweeping all .env variants in the working directory. The version history reveals live debugging by the attacker, who iteratively refined the payload targeting and stealth capabilities while the package remained publicly available with approximately 19,830 monthly downloads.