# MAL-2026-13043: Malicious code in boxy-expander-contract (npm)


- **Type:** Malicious package
- **Package:** `boxy-expander-contract` (npm)
- **Published:** 5 Aug 2026

## What is MAL-2026-13043?

MAL-2026-13043 is a malicious package in boxy-expander-contract, published on 5 Aug 2026. 

### Official description

On require() of this package, index.js loads./_runtime.js which assembles Cloudflare Workers hostnames via string-split.join('') fragments (e.g. oob-worker.cf103-070.workers.dev, oob-worker.cf100-416.workers.dev, oob-worker.cf99-9b3.workers.dev, oob-worker.cf101-adf.workers.dev) with a DNS-TXT fallback under *.dl.wel1.ru (sdk.dl.wel1.ru, ext.dl.wel1.ru, pkg.dl.wel1.ru, net.dl.wel1.ru), downloads a platform-specific binary via https.get, writes it to /tmp or %TEMP% under a name masquerading as system tooling (dotnet_diag_*.exe,.cache_*), chmods 755 on unix, and spawns it detached via spawn('/bin/sh', ['-c',...]) or spawn('cmd',...). No hash or signature verification is performed and destination hosts are string-fragmented to evade static analysis. The package's advertised API is an unrelated decoy stub.

## What should I do about MAL-2026-13043?

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-2026-13043 is a malicious package: boxy-expander-contract (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-2026-13043/ (Markdown: https://insights.sbomify.com/MAL-2026-13043/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/MAL-2026-13043

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From sbomify Insights: https://insights.sbomify.com/MAL-2026-13043/
Summaries are generated and may contain mistakes; the official description above is the record.