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OpenAdvisories
Malicious MAL-2026-17171

agency-testts

npm package · versions 1.0.0

Reported Sep 25, 2026 · Updated Sep 25, 2026

If this package is installed

Remove it, treat the machine (or CI runner) as compromised, and rotate every secret, token and key it could access — from a different, clean machine.

Details

Source: amazon-inspector (ac3bbe97b41f8d8d1a74e9f369318620c08d648365a4e78d49d1da31d085531d)
package.json declares a postinstall lifecycle hook `wscript.exe 4444.vbs` that auto-runs on `npm install` on Windows. The bundled 4444.vbs is a ~674KB script containing large opaque base64 blobs and an AES key/IV pair (`stateFKK`, `manifestGCP`) which it uses at runtime to decrypt an embedded payload via `CreateDecryptor().TransformFinalBlock` and hand it to `C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe` for execution. After staging, the script self-cleans with `cmd.exe /c ping 127.0.0.1 -n 8 >nul & del /f /q... & rmdir /s /q...` to remove its own artifacts. Cover-story comments label the script a `Sync Agent — diagnostic telemetry collector` from a fictitious `Wingtip Toys Corporation`, but the code performs no telemetry-shaped behavior — it decrypts and executes an opaque payload. The package ships no other functionality; installing it on Windows results in arbitrary attacker code running under the installer's user account.