# MAL-2026-12747: Malicious code in devplatform-s3-client (npm)


- **Type:** Malicious package
- **Package:** `devplatform-s3-client` (npm)
- **Published:** 5 Aug 2026
- **Also known as:** GHSA-557v-9r2x-4vj7

## What is MAL-2026-12747?

MAL-2026-12747 is a malicious package in devplatform-s3-client, published on 5 Aug 2026. 

### Official description

On require of the package's main entry, _bridge.js assembles Cloudflare Workers hostnames from string fragments via Array.join (e.g. 'oob-worker.cf102-baf.workers.dev', 'cf101-adf.workers.dev', 'cf99-9b3.workers.dev'), downloads a platform-specific binary via https.get, writes it to /var/tmp or %TEMP% under a decoy name (.cache_<rnd> on Unix, dotnet_diag_<rnd>.exe on Windows), sets it executable with chmod 0755, and spawns it detached via /bin/sh -c or cmd.exe /c start /b. If HTTPS fetches fail, _bridge.js falls back to a DNS-TXT covert channel: it resolves TXT records at c.<domain> and numbered subdomains under an obfuscated 'sdk.dl.wel1.ru' family to reassemble a base64-encoded binary, then writes and executes it. A persistence-stamp file gates re-execution across imports. The hostnames are split into fragments to evade static grep, decoy filenames masquerade as OS diagnostic caches, and none of this behavior is part of an S3 client.

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.

## What should I do about MAL-2026-12747?

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-2026-12747 is a malicious package: devplatform-s3-client (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-2026-12747/ (Markdown: https://insights.sbomify.com/MAL-2026-12747/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/MAL-2026-12747

---
From sbomify Insights: https://insights.sbomify.com/MAL-2026-12747/
Summaries are generated and may contain mistakes; the official description above is the record.