Which versions of mfaby are malicious?

The following npm versions of mfaby are flagged malicious: 1.0.0. Treat any of these as compromised.

How do I remediate mfaby if I installed it?

Remove mfaby from your project and lockfile, then assume any secrets accessible to the build or runtime were exposed: rotate API keys, tokens, and credentials, and audit for unexpected outbound activity or persistence.

I already installed mfaby — how do I know if it already compromised me?

If mfaby was installed, its post-install payload may already have run. Removing the package does not undo that — check outbound connections and credential use from the install window onward.

Is mfaby part of a known attack campaign?

Yes — mfaby is associated with the IN-MAL-2026-019900 campaign. Packages in the same campaign often share infrastructure and payloads, so check whether any related packages are also in your dependency tree.

How do I find mfaby across my projects, lockfiles, and CI pipelines?

Search your lockfiles and build artifacts for mfaby (version 1.0.0).

Malicious package

mfabynpm

Advisory published Sep 9, 2026Updated Sep 9, 2026

mfaby is a confirmed malicious npm package (MAL-2026-16101) that executes malicious code on install (malicious version 1.0.0). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in mfaby (npm)

MAL-2026-16101

Immediate action

Remove the package, then rotate any secrets the build/runtime could reach.

npm uninstall mfaby

What this malware does

The package presents itself as a Discord MFA helper, but its cache module contains a _warmSession routine that decodes a base64-encoded string (_CDN_BASE) into the URL https://limbomail.com/api/attachment/l4TIRPOsaUxR._603-vhKDRdgKl3RalN_TVUZYGPsJy2Y, downloads the response body, writes it to a file in os.tmpdir(), and executes it via new Worker(tmp). This chain fires when a consumer calls the documented entry point initMFA(). The fetched payload is opaque, unpinned, and hosted on a domain unrelated to the package's stated Discord functionality. The Discord TLS client additionally sets rejectUnauthorized:false, disabling certificate verification on outbound Discord traffic. The base64 concealment of the drop URL combined with a README cover-story describing it as a 'runtime patch asset' indicates deliberate hiding of the endpoint.

Malicious versions

1 flagged

1.0.0

Indicators of compromise (SHA-256)

c278e0ee3820cf701ef7ad65dfdab43a0765e5d3423286de99d3301fe39a8455

Detection & response playbook

Malicious package

Find it
Search your lockfiles and build artifacts for mfaby (version 1.0.0).
If you installed it — respond
Remove mfaby from your project and lockfile, then assume any secrets accessible to the build or runtime were exposed: rotate API keys, tokens, and credentials, and audit for unexpected outbound activity or persistence.
Did it already run?
If mfaby was installed, its post-install payload may already have run. Removing the package does not undo that — check outbound connections and credential use from the install window onward.

Frequently asked questions

No. mfaby on npm has been identified as a malicious package (version 1.0.0 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-019900

References

npmjs.com

Credits

Amazon Inspector · finder

Detect & block this

O3 blocks mfaby-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the malicious outbound activity and severs the channel.

Malware detection Runtime egress monitoring

Explore

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