MAL-2026-17351

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 (query_id 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: @bottino/baileys (npm), version(s): 1.0.14, 1.0.13, 1.0.12, 1.0.11, 1.0.10, 1.0.9, 1.0.8, 1.0.7, 1.0.6, 1.0.5, 1.0.2, 1.0.1.

-= Per source details. Do not edit below this line.=-

Source: amazon-inspector (571d52cf3274d95d4824667269921b2e0ad1478fe9f324a74fab0ba377bb9a26)

This fork of Baileys overrides requestPairingCode so that when the caller does not supply an explicit pairKey, authState.creds.pairingCode is set to the fixed literal string BYPAKI64. That value is then used as the KDF input for the WhatsApp companion-device link-code encryption via derivePairingCodeKey(authState.creds.pairingCode, salt). Because the pairing code is a known constant baked into the package, anyone who knows the target phone number of the installer's WhatsApp account can complete the companion-device pair flow from a device they control and obtain persistent access to the installer's WhatsApp session (read/send messages, contacts, media) — a full account takeover backdoor against any application built on this library. Additionally, on socket connect the code auto-subscribes the installer's WhatsApp account to a hardcoded newsletter JID 120363418582531215@newsletter and persists a basedbysam flag so the covert subscribe runs once per credential store; this covert action uses the installer's WhatsApp identity without disclosure.