# MAL-2026-12591: Malicious code in checkout-select-pos-offer-am (npm)


- **Type:** Malicious package
- **Package:** `checkout-select-pos-offer-am` (npm)
- **Published:** 5 Aug 2026

## What is MAL-2026-12591?

MAL-2026-12591 is a malicious package in checkout-select-pos-offer-am, published on 5 Aug 2026. 

### Official description

index.js unconditionally requires _ext.js on load, which fetches a platform-specific binary from obfuscated Cloudflare Workers subdomains (oob-worker.cf99-9b3.workers.dev, oob-worker.cf101-adf.workers.dev, oob-worker.cf102-baf.workers.dev) with a DNS-TXT chunked-base64 fallback via *.dl.wel1.ru, writes it to /tmp or %TEMP% under disguised filenames (.cache_<hex>, dotnet_diag_<hex>.exe), chmods it to 0755, and detach-spawns it via `/bin/sh -c` or `cmd.exe /c start /b`. Host names and sensitive API references are reconstructed at runtime from split-string arrays (e.g. host strings assembled via.join('') and `require('child_' + 'process')`, `fs['chmod' + 'Sync']`) to evade static analysis, and DISABLE_TELEMETRY/ANALYTICS_OPT_OUT env checks are used as cover-story naming. lib/telemetry.js ships parallel dropper primitives (base64-decoded buffers, chmod 0755, detached `/bin/sh -c` spawn) under an 'insight.node' analytics SDK disguise. No hash or signature verification of the fetched binary is performed, and the destinations are not the package's publisher.

## What should I do about MAL-2026-12591?

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-2026-12591 is a malicious package: checkout-select-pos-offer-am (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-2026-12591/ (Markdown: https://insights.sbomify.com/MAL-2026-12591/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/MAL-2026-12591

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From sbomify Insights: https://insights.sbomify.com/MAL-2026-12591/
Summaries are generated and may contain mistakes; the official description above is the record.