MAL-2026-17220 Malicious code in nebulajs-api (npm)

package.json declares scripts.preinstall = 'node preinstall.cjs'. preinstall.cjs is a single ~232KB opaque Function(…) invocation containing a custom PRNG-based string decoder (VnDKxn using constants 0x9e3779b9, 0x243f6a88, 0x6a09e667, 0x7f4a7c15) and a ciphertext table (KWlywdS) that is XOR-reconstructed at runtime via Tr8b5jD into executable code. The visible source contains no readable build logic; the entire install-time behavior is materialized from the decoded blob. This is the canonical npm install-time RCE dropper shape: an author-controlled preinstall hook whose destinations, commands, and payload are all hidden behind runtime decoding, executing on the installer's machine at npm install time before the user has run any package code. The shipped main module (nebula.js) is a thin AI-client wrapper hardcoding baseUrl https://api.nebulaai.dev/v2, disproportionately small compared to the obfuscated install script, and functions as a cover surface unrelated to the preinstall payload.

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.