# MAL-2026-12463: Malicious code in streak-day-primitives (npm)


- **Type:** Malicious package
- **Package:** `streak-day-primitives` (npm)
- **Published:** 5 Aug 2026
- **Also known as:** GHSA-792g-8w6v-23q8

## What is MAL-2026-12463?

MAL-2026-12463 is a malicious package in streak-day-primitives, published on 5 Aug 2026. 

### Official description

The package advertises itself as dependency-free calendar-day arithmetic, but index.mjs contains top-level code that runs on import. All sensitive strings — module names ('child_process', 'https'), the remote URL, tar arguments, PowerShell flags, the WScript.Shell COM object, the Startup folder path, and the payload executable name — are hex-encoded and reassembled at runtime via a `Buffer.from(s,'hex').toString()` helper (`_d` + `_k` table) to hide the payload from static review. When the host is Linux with WSL_DISTRO_NAME set and /mnt/c is reachable, the code fetches a tarball from https://f004.backblazeb2.com/file/dp8hbvocjd2fpza/helper.tar.gz, extracts it into the Windows user's AppData tree, and uses PowerShell (-NoProfile -WindowStyle Hidden -ExecutionPolicy Bypass) plus WScript.Shell CreateShortcut to drop a.lnk pointing at the extracted RenameMe.exe into the Windows user's Startup folder. This is a WSL-to-Windows escape that grants the attacker code execution on the installer's Windows host at next login, with no relation to the package's stated purpose.

Any computer that has this package installed or running should be considered fully compromised. All secrets and keys stored on that computer should be rotated immediately from a different computer. The package should be removed, but as full control of the computer may have been given to an outside entity, there is no guarantee that removing the package will remove all malicious software resulting from installing it.

## What should I do about MAL-2026-12463?

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-2026-12463 is a malicious package: streak-day-primitives (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-2026-12463/ (Markdown: https://insights.sbomify.com/MAL-2026-12463/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/MAL-2026-12463

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From sbomify Insights: https://insights.sbomify.com/MAL-2026-12463/
Summaries are generated and may contain mistakes; the official description above is the record.