# MAL-2026-17171: Malicious code in agency-testts (npm)


- **Type:** Malicious package
- **Package:** `agency-testts` (npm)
- **Published:** 25 Sep 2026

## What is MAL-2026-17171?

MAL-2026-17171 is a malicious package in agency-testts, published on 25 Sep 2026. 

### Official description

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.

## What should I do about MAL-2026-17171?

Remove the package from your dependencies and lockfiles, then rotate any secrets on machines where it was installed.

## Fix prompt for AI coding agents

```text
MAL-2026-17171 is a malicious package: agency-testts (npm). Every version was published to cause harm.

Task:
1. Search this repository's dependency manifests and lockfiles for the package, including transitive dependencies.
2. If it is present, remove it, regenerate the lockfile with the project's package manager, and replace whatever it was used for.
3. List any CI runners, developer machines or containers that installed it, so their secrets can be rotated.
4. If the package is not used anywhere, say so and change nothing.

Reference: https://insights.sbomify.com/MAL-2026-17171/ (Markdown: https://insights.sbomify.com/MAL-2026-17171/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/MAL-2026-17171

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From sbomify Insights: https://insights.sbomify.com/MAL-2026-17171/
Summaries are generated and may contain mistakes; the official description above is the record.