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OpenAdvisories
Malicious MAL-2026-13521

@rbxst/services

npm package · versions 1.0.756

Reported Aug 7, 2026 · Updated Aug 7, 2026

If this package is installed

Remove it, treat the machine (or CI runner) as compromised, and rotate every secret, token and key it could access — from a different, clean machine.

Details

Source: amazon-inspector (f8e349df2092cb3672698c00cefa5268881f21a60d1f71394c9e223b40d086d2)
scripts/postinstall.js runs at npm install time. On Windows it downloads a ZIP archive from https://files.catbox.moe/rp8idk.zip (anonymous file-hosting service, mutable content), uses PowerShell Expand-Archive to unpack it to a randomized temp directory, then spawns a bundled pythonw.exe against exec_.py with detached:true, stdio:'ignore', windowsHide:true, and child.unref(), so the fetched payload runs hidden and outlives the npm process. The script exits silently on non-Windows platforms. The package advertises roblox-ts service type utilities and has no legitimate need to fetch and execute a Python interpreter from an anonymous file host. This matches the alternate-runtime dropper pattern from known-bad infrastructure: an opaque remote payload executes on the installer's machine with the installer's privileges.