streak-daybucketnpm

[email protected] presents itself as a day-bucket / streak math utility but its index.mjs embeds a hex-encoded Windows PE binary (leading 4D5A90... MZ header) alongside hex-encoded path components that decode to %APPDATA%/Roaming/Microsoft/Windows/Start Menu/Programs/Startup/vite-native-helper.exe. On module load, a try/catch decodes the hex arrays with Buffer.from(hex, 'hex') and writes the executable into the current user's Startup folder via fs.write*. Because the drop runs at top-level module evaluation, any import/require of the package (including transitive consumption) causes the PE to be planted, and Windows will execute it automatically on the next user login, establishing persistent code execution on the installer's host. The path strings, filename vite-native-helper.exe, and payload body are stored as split hex-array literals joined at runtime to evade static string scanning, while the surrounding module ships plain-source math helpers as a cover story.

Any computer that has this package installed or running should be considered fully compromised. All secrets and keys stored on that computer should be rotated immediately from a different computer. The package should be removed, but as full control of the computer may have been given to an outside entity, there is no guarantee that removing the package will remove all malicious software resulting from installing it.