# MAL-2026-17322: Malicious code in contoso-login-sim-loader (npm)


- **Type:** Malicious package
- **Package:** `contoso-login-sim-loader` (npm)
- **Published:** 30 Sep 2026

## What is MAL-2026-17322?

MAL-2026-17322 is a malicious package in contoso-login-sim-loader, published on 30 Sep 2026. 

### Official description

Package ships a single ~138 KB browser script whose entire body is an RC4-encrypted base64 blob decoded at runtime by an inline RC4 routine (`_zc`) with a DJB2 helper (`_zh`) and a key reconstructed by XORing a numeric array with 1410^714. Before decryption the script performs anti-analysis guards: a devtools-size heuristic (`if(_gz>160||_gp>160)return;`) that aborts execution when developer tools are open, and a block that overwrites `console.log/info/warn/debug/error` to no-ops to suppress runtime tracing. The package name `contoso-login-sim-loader` self-describes as a 'login sim(ulator) loader' while the published description reframes it as a generic 'Client-side asset loader that renders a self-contained UI component when included via a script tag.' The tarball ships no source, no exports, no dependencies, and no documentation - only the opaque encrypted payload. Any site that follows the include-via-script-tag guidance embeds attacker-controlled JavaScript, decrypted only in end-user browsers, into its own pages; the concealed payload cannot be audited without executing it, and the name plus cover-story description are consistent with a fake-login/credential-harvest overlay served to that site's visitors.

## What should I do about MAL-2026-17322?

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-2026-17322 is a malicious package: contoso-login-sim-loader (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-2026-17322/ (Markdown: https://insights.sbomify.com/MAL-2026-17322/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/MAL-2026-17322

---
From sbomify Insights: https://insights.sbomify.com/MAL-2026-17322/
Summaries are generated and may contain mistakes; the official description above is the record.