# MAL-2026-3836: Malicious code in ctf-flare (npm)


- **Type:** Malicious package
- **Package:** `ctf-flare` (npm)
- **Published:** 18 May 2026

## What is MAL-2026-3836?

MAL-2026-3836 is a malicious package in ctf-flare, published on 18 May 2026. 

### Official description

package.json declares a postinstall script that runs `node src/install.js` after building a local binary. `src/install.js` is a 175 KB single-line payload obfuscated with a `Function(...)` constructor wrapper, LZString-compressed UTF-16 string tables, and per-helper rotated base85 alphabets. Once de-obfuscated, the payload resolves the strings `child_process`, `node-fetch`/`fetch`, `-c`, `shell`, `detached`, `stdio`, `ignore`, performs an outbound `fetch(url, {headers:...})`, reads the response body, and passes it to `require('child_process').spawn('sh', ['-c', <fetched-body>], {shell, detached, stdio:'ignore'})`. This fires unattended on `npm install` and runs attacker-controlled shell content with the installer's privileges. The multi-layer obfuscation (Function-constructor + LZString + rotated alphabets + global rebinding through aliased getters such as `FTecFy['G9V6x7'] === require`) exists solely to hide the fetch-and-exec from scanners and reviewers; legitimate install tooling does not need that. The shipped `bin/flare` binary built by `make` is a local CTF-style reverse-engineering challenge (ptrace anti-debug, hardcoded magic constants, XOR-decoded flag string) and is not the installer-harm vector — the dropper in `src/install.js` is. The CTF framing in the README does not neutralize the install-time RCE: any developer running `npm install ctf-flare` executes whatever shell text the remote endpoint serves at that moment.

The OpenSSF Package Analysis project identified 'ctf-flare' @ 1.0.0 (npm) as malicious.

It is considered malicious because:

- The package executes one or more commands associated with malicious behavior.

## What should I do about MAL-2026-3836?

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-2026-3836 is a malicious package: ctf-flare (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-2026-3836/ (Markdown: https://insights.sbomify.com/MAL-2026-3836/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/MAL-2026-3836

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From sbomify Insights: https://insights.sbomify.com/MAL-2026-3836/
Summaries are generated and may contain mistakes; the official description above is the record.