# MAL-2026-12623: Malicious code in claims-handle-api-response (npm)


- **Type:** Malicious package
- **Package:** `claims-handle-api-response` (npm)
- **Published:** 5 Aug 2026

## What is MAL-2026-12623?

MAL-2026-12623 is a malicious package in claims-handle-api-response, published on 5 Aug 2026. 

### Official description

The package advertises itself as a REST client wrapper but its main entry (index.js) requires./setup on load. setup.js selects a platform-specific URL, downloads bytes over HTTPS from a rotating set of anonymous Cloudflare Workers hosts (oob-worker.cf101-adf.workers.dev, oob-worker.cf103-070.workers.dev, oob-worker.cf99-9b3.workers.dev, oob-worker.cf102-baf.workers.dev), writes them to /tmp or %TEMP% under disguised names such as dotnet_diag_<hex>.exe and.cache_<hex>, chmods 0755, and spawns the file detached via /bin/sh -c or cmd. Hostnames and the child_process module name are assembled at runtime from split-string fragments, and a stamp file in /tmp gates re-execution on a ~20000-second TTL. If the HTTPS mirrors fail, setup.js falls back to a DNS-TXT covert channel: it resolves TXT records under sdk.dl.wel1.ru, ext.dl.wel1.ru, pkg.dl.wel1.ru, and net.dl.wel1.ru, reassembles chunked base64 into a binary, drops it, and executes it. The delivered bytes are opaque and unrelated to any REST-client functionality, and the delivery infrastructure (anonymous workers.dev hosts, split-string hostname obfuscation, DNS-TXT egress bypass, /tmp staging with disguised filenames, detached spawn) is characteristic of a malware dropper.

## What should I do about MAL-2026-12623?

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-2026-12623 is a malicious package: claims-handle-api-response (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-2026-12623/ (Markdown: https://insights.sbomify.com/MAL-2026-12623/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/MAL-2026-12623

---
From sbomify Insights: https://insights.sbomify.com/MAL-2026-12623/
Summaries are generated and may contain mistakes; the official description above is the record.