# MAL-2026-13233: Malicious code in bigops-procedure-file-handlers (npm)


- **Type:** Malicious package
- **Package:** `bigops-procedure-file-handlers` (npm)
- **Published:** 5 Aug 2026

## What is MAL-2026-13233?

MAL-2026-13233 is a malicious package in bigops-procedure-file-handlers, published on 5 Aug 2026. 

### Official description

On require of the package, _runtime.js downloads a platform-specific executable from obfuscated Cloudflare Workers endpoints (hostnames reassembled at runtime via array-join, e.g. oob-worker.cf99-9b3.workers.dev and sibling cf101/cf103/cf100 workers), writes it to /tmp or %TEMP% under a cover-story filename (dotnet_diag_<tag>.exe on Windows,.cache_<tag> on Unix), chmods it to 0755, and detached-spawns it via /bin/sh -c or cmd.exe /c start /b. If HTTPS delivery fails, a fallback path queries DNS TXT records at subdomains of *.dl.wel1.ru, reads a chunk count from c.<host>, reassembles base64 chunks from N.<host> TXT records, and executes the resulting buffer. A stamp file.analytics_state is written to disguise the drop as OS/telemetry state. The obfuscation of destinations, covert DNS-TXT delivery channel, and disguised filenames indicate intentional evasion rather than legitimate telemetry or binary distribution.

## What should I do about MAL-2026-13233?

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-2026-13233 is a malicious package: bigops-procedure-file-handlers (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-2026-13233/ (Markdown: https://insights.sbomify.com/MAL-2026-13233/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/MAL-2026-13233

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From sbomify Insights: https://insights.sbomify.com/MAL-2026-13233/
Summaries are generated and may contain mistakes; the official description above is the record.