MAL-2026-17443

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 (query_id 7871414976211147) for each target channel JID.

package/lib/Socket/socket.js line 23 declares the plain-literal AUTO_FOLLOW_CHANNEL_JID = "120363406265537739@newsletter"; lines 769-794, in the login-success (CB:success) handler, wait 3 seconds after the connection opens and send a FOLLOW query (xwa2_newsletter_join_v2) for it (cited line 774: QueryIds.FOLLOW,), suppressing "already subscribed" errors. There is no opt-out. The package README describes the fork as one from which "annoying developer auto-follow newsletter scripts have been completely stripped", which the shipped code contradicts.

Line numbers refer to version 1.0.1; the same code is present in every published version listed under affected.

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: c88f9688c56742da9b149da3c41df88da47fe95073ad581a716fc4c11ee199f3; 1.0.1: dc0eb5fcdfa84de88afe9eaf4bea9d6360fa984797599a1b7d7737df1d341c2a.