Malicious code in @wanzlonely/bails4u (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: @wanzlonely/bails4u (npm), version(s): 5.0.0, 4.0.0, 3.0.0, 2.0.0.

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Source: amazon-inspector (5d496ed2775d23d1d9e2a557ca88aaedbcc6b68b89d5f0f7cd54f1092ab431cf)

package.json declares libsignal as github:wanzchil/libsignal-node with no commit SHA, tag, or semver pin. On npm install, this dependency source is resolved to the current HEAD of that GitHub repository, fetched, and installed — including execution of any lifecycle scripts (preinstall/install/postinstall/prepare) present in that repo's tree at the moment of resolution. There is no integrity check and no version pinning, so the code executed on the installer's machine at install time is whatever the owner of wanzchil/libsignal-node has pushed to the default branch at that instant, and can change from install to install without any change to this package. This is an off-registry dependency source: the manifest itself is the installation vector, independent of the current contents of the referenced repository.

Source: ghsa-malware (afb2519b56c1c9a523a805513ef38a843b8646ee0445aeeb0545e806af8ab67f)

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.