MAL-2026-17440: Malicious code in @erlanzz/baileys (npm)

This package is a fork of the Baileys WhatsApp Web library (npm) and belongs to the "PhantomSub" family described by OX Security in September 2026: the publisher injected code that, without the installer asking, uses the installer's own authenticated WhatsApp session to subscribe that account to WhatsApp Channels (newsletters) the publisher chose, by sending the WhatsApp w:mex FOLLOW query (queryid 7871414976211147) for each target channel JID.

package/lib/Socket/newsletter.js lines 47-65 (cited line 58: QueryIds.FOLLOW) define an array of three base64 strings and, 90 seconds after the newsletter socket is created, decode each with Buffer.from(channel, "base64") and send a FOLLOW query, 6 seconds apart. Decoded JIDs: 120363387182851100@newsletter, 120363371199176376@newsletter and 120363421367985094@newsletter. There is no opt-out and the behavior is not documented.

Line numbers refer to version 1.0.0.

Static review of the published tarball(s) found no code that sends WhatsApp credentials or session keys off-host, no install-time payload (the only install hook is Baileys' stock Node.js version check in engine-requirements.js), and no persistence; the payload runs when an application creates a WhatsApp socket with the library. The harm is the covert use of the victim's account to inflate the publisher's channel subscribers.

SHA-256 of the published npm tarball(s): 1.0.0: 9bc787ecc07e18d2504ab4e06e97d86d13a9952515a529a28b53a227d247b294.

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Source: ghsa-malware (6eaa9b634619c736498725a51a628ac35194f85ebbaca35896de2704fbe3fdf7) 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.