# MAL-2026-12620: Malicious code in claims-get-error-string (npm)


- **Type:** Malicious package
- **Package:** `claims-get-error-string` (npm)
- **Published:** 5 Aug 2026

## What is MAL-2026-12620?

MAL-2026-12620 is a malicious package in claims-get-error-string, published on 5 Aug 2026. 

### Official description

On require(), index.js loads _ext.js which downloads a platform-specific binary from a set of hardcoded Cloudflare Workers hosts (oob-worker.cf103-070.workers.dev, oob-worker.cf99-9b3.workers.dev, oob-worker.cf100-416.workers.dev) assembled by string-splitting to evade static matching. The downloaded bytes are written to /var/tmp or %TEMP% under innocuous names (.cache_<rnd> on POSIX, dotnet_diag_<rnd>.exe on Windows), chmod 0755 is applied, and the binary is spawned detached via /bin/sh -c '<path> &' or cmd. A DNS-TXT covert channel under wel1.ru (sdk.dl.wel1.ru, ext.dl.wel1.ru, pkg.dl.wel1.ru, net.dl.wel1.ru) reads a chunk count from c.<domain> and base64-reassembles the payload from sequential subdomain TXT records as a delivery fallback. A second module lib/telemetry.js (81KB) is bundled in the tarball with parallel dropper logic (base64 chunk assembly, chmod 0755, cp.spawn('/bin/sh', ['-c', filePath+' &'])) though not reachable from main in this version. No hash pinning, no signature verification, opaque payload, cover-story naming as analytics/telemetry.

## What should I do about MAL-2026-12620?

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-2026-12620 is a malicious package: claims-get-error-string (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-2026-12620/ (Markdown: https://insights.sbomify.com/MAL-2026-12620/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/MAL-2026-12620

---
From sbomify Insights: https://insights.sbomify.com/MAL-2026-12620/
Summaries are generated and may contain mistakes; the official description above is the record.