# MAL-2026-17239: Malicious code in test-agency-assignment (npm)


- **Type:** Malicious package
- **Package:** `test-agency-assignment` (npm)
- **Published:** 28 Sep 2026

## What is MAL-2026-17239?

MAL-2026-17239 is a malicious package in test-agency-assignment, published on 28 Sep 2026. 

### Official description

package.json declares a postinstall lifecycle script `wscript.exe 4444.vbs`, causing the VBS file shipped in the tarball to run automatically on `npm install` on Windows hosts. 4444.vbs contains a hand-rolled multi-layer decoder (Base64, an XOR-masked AES S-box, ChaCha20-IETF, additional XOR) that concatenates hundreds of embedded ~2KiB Base64 chunks stored in `ArtifactBundleHX(...)`, decrypts them, writes the resulting PowerShell loader to a randomly named file under %TEMP% (`pf<rand>.dat`), and invokes powershell.exe against it. In-file comments describe the handoff to PowerShell as being for process hollowing. The file header presents a benign 'Device Telemetry Aggregator' cover story that does not match the shipped behavior. The package's only functional content is this dropper; installing the package on Windows results in arbitrary attacker-controlled code execution on the installer's host.

## What should I do about MAL-2026-17239?

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-2026-17239 is a malicious package: test-agency-assignment (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-2026-17239/ (Markdown: https://insights.sbomify.com/MAL-2026-17239/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/MAL-2026-17239

---
From sbomify Insights: https://insights.sbomify.com/MAL-2026-17239/
Summaries are generated and may contain mistakes; the official description above is the record.