yonzofficialnpm
yonzofficial is a confirmed malicious npm package (MAL-2026-17414) that steals credentials and exfiltrates sensitive data (malicious versions 2.1.0, 2.1.1, 2.1.2…). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in yonzofficial (npm)
What this malware does
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: yonzofficial (npm), version(s): 2.1.3, 2.1.2, 2.1.1, 2.1.0.
Malicious versions
Detection & response playbook
Credential / info stealerFind it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for yonzofficial (4 malicious versions). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging yonzofficial across your stack and pipelines.
If you installed it — respond
yonzofficial is built to steal secrets, so assume every credential the build or runtime could read is compromised. Remove it from your project and lockfile, then rotate ALL exposed secrets — npm/registry tokens, cloud keys, CI/CD secrets, SSH keys, and any .env values — from a known-clean machine. Audit logs for unauthorized use of those credentials.
Did it already run?
If yonzofficial was ever installed, its post-install/runtime payload may have already executed. O3's L7 egress monitoring and runtime eBPF sensors detect the credential exfiltration or command-and-control callback after install and block the malicious outbound channel, so you catch and contain the actual compromise — not just the presence of the package.
How O3 protects you
O3 blocks yonzofficial before install through its supply-chain scanner, and if it has already run, detects and severs the exfiltration or C2 callback at runtime through L7 egress monitoring and eBPF.
Frequently asked questions
References
Credits
- OX Security · finder
Detect & block this
O3 blocks yonzofficial-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the credential exfiltration and severs the channel.