MAL-2026-17374: Malicious code in @rennnpm/baileys (npm)
This package is part of a large family (100+ identified as of September 2026) of near-identical forks of the Baileys WhatsApp Web library that inject a covert channel-subscription action into the WhatsApp socket layer. On connect, the injected code issues an authenticated w:mex FOLLOW query (queryid 7871414976211147) against one or more attacker-chosen WhatsApp Channel/Newsletter JIDs, using the installer's own authenticated WhatsApp session -- silently subscribing the victim's account to channels it never asked to join.
The target JID(s) are hidden from casual source review via one of several obfuscation techniques observed across the family: a plain string literal, base64 encoding, base64+XOR, or a char-code array reconstructed at runtime. Some variants instead fetch a mutable, attacker-controlled remote JSON/JS list of target JIDs from GitHub or another host at runtime, letting the target list change after installation without a new npm publish. Every sample in the family shares the same underlying mechanism (a wrapped/patched socket-connect routine that fires the FOLLOW query some seconds after connect), even though the package name, JID value(s), and obfuscation/delivery method differ per fork.
The malicious action abuses the installer's own authenticated WhatsApp session to gain reach and subscribers for attacker-controlled channels; it does not exfiltrate credentials, establish persistence, or execute arbitrary remote code.
Affected package: @rennnpm/baileys (npm), version(s): 1.0.0.
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Source: amazon-inspector (1147bf0a20408ab406838da0e6aa5a2086deb1afe6651013a6081714ada641ff) package.json declares the libsignal dependency as github:tenka-san/libsignal-node, a bare GitHub reference to a personal user's fork with no commit SHA, tag, or version constraint. On npm install, npm clones the default branch's current HEAD and runs any lifecycle scripts the fetched repository declares, executing that code on the installer's machine with no integrity check. Whoever controls the tenka-san/libsignal-node repository can change the code at any time, and every installer of this package will run whatever is at HEAD at that moment. The upstream @whiskeysockets/baileys package resolves libsignal from the npm registry at a pinned version; substituting a mutable third-party git reference in this fork replaces a registry-integrity-checked dependency with an unpinned attacker-controllable code source.