MAL-2026-17404 Malicious code in saturn-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 (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: saturn-baileys (npm), version(s): 1.0.0.

saturn-baileys is a fork of the Baileys WhatsApp library. In lib/Socket/messages-send.js at lines 425 and 436, a network destination is reconstructed at runtime from a String.fromCharCode(…) decimal array rather than appearing as a plain string literal. The decoded value is the URL https://fiora.nixel.my.id/. The obfuscation is placed inside the message-send code path of a messaging library that handles user credentials, session data, and message content, and the destination is not a documented WhatsApp/Baileys endpoint. Reconstructing a hardcoded non-first-party host via char-code decoding inside a send routine is the exfiltration/silent-relay shape for messaging-library trojans and is inconsistent with any legitimate use in this location.