serpacksven1npm

The tarball ships no JavaScript — the declared main: index.js is absent — and contains only 10 byte-identical copies of a PowerShell dropper under misleading extensions (1.png, client.doc, client.doc.1, json.txt, extensionless client, all sha256 e9dff494...). The script hides the console window via Win32 APIs, concatenates ~150 base64 chunks, XOR-decodes them with single-byte key 89, reflectively resolves [System.Reflection.Assembly].Load through char-code-obfuscated type strings, and invokes the decoded in-memory.NET assembly. The package has no lifecycle scripts and no importable surface, so npm install alone does not execute the payload; the harm fires when a second-stage tool or downstream workflow sources any of the disguised files (e.g. powershell -File client.doc), delivering full-host code execution of an attacker-controlled.NET assembly on Windows. The multi-extension disguise, byte-identical duplication, and absence of any legitimate package content show this is a payload-staging artifact published to npm rather than a software package.

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.