Which versions of mutex-plus are malicious?

The following npm versions of mutex-plus are flagged malicious: 3.0.2. Treat any of these as compromised.

How do I remediate mutex-plus if I installed it?

mutex-plus establishes remote access, so treat any host that installed it as fully compromised. Isolate the machine, remove the package, rotate all credentials it could reach, and rebuild from a trusted image rather than cleaning in place — a backdoor may have planted additional persistence.

I already installed mutex-plus — how do I know if it already compromised me?

If mutex-plus 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.

Is mutex-plus part of a known attack campaign?

Yes — mutex-plus is associated with the IN-MAL-2026-018396 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 mutex-plus across my projects, lockfiles, and CI pipelines?

Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for mutex-plus (version 3.0.2). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging mutex-plus across your stack and pipelines.

Malicious package

mutex-plusnpm

mutex-plus is a confirmed malicious npm package (MAL-2026-14282) that opens a backdoor for remote access (malicious version 3.0.2). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in mutex-plus (npm)

MAL-2026-14282

Immediate action

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

npm uninstall mutex-plus

What this malware does

lib/Mutex.js contains a hidden branch inside runExclusive() that, when a callback object carries a meta.jobId whose sha256 equals a hardcoded value (6cdda0ba143b3bee5949d3d45d2145c53c02abfe0e742465cdce2c0393e94d7f), invokes decryptToFile() from an obfuscated helper lib/common.js to AES-256-GCM-decrypt the shipped lib/plusMutex.min.js using the caller-supplied jobId as the key, then spawns the decrypted file via node as a detached, stdio-ignored, windowsHide child process. lib/common.js is a string-array + index-rotation obfuscated module wrapping scryptSync + createDecipheriv + writeFileSync; it is required only from this hidden branch. lib/plusMutex.min.js (16.9 KB, sha256 903169c2602ad15ba2dbc3c1e791bd26561958508d7d8a7ce35fc7d53c6212e1) is the AES-256-GCM ciphertext; sibling files lib/plusMutex.min.d.js (862 KB) and lib/tryAcquireMutex.min.d.js use a fabricated .d.js extension (real TypeScript declarations are .d.ts) to disguise executable/binary content as declaration artifacts. A mutex primitive has no functional need for encrypted-at-rest sibling blobs, an obfuscated GCM decryptor, or a hash-gated detached node spawn. The construction gives whoever holds the correct jobId — the decryption key — remote code execution on any consumer of Mutex.runExclusive that receives a crafted callback object, with the payload undecryptable without that key.

Malicious versions

1 flagged

3.0.2

Indicators of compromise (SHA-256)

a64e56572436d2ca889aa389887584bbeb3e67df09f30df6773cbfafc0188ca3

Detection & response playbook

Backdoor / remote access

Find it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for mutex-plus (version 3.0.2). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging mutex-plus across your stack and pipelines.
If you installed it — respond
mutex-plus establishes remote access, so treat any host that installed it as fully compromised. Isolate the machine, remove the package, rotate all credentials it could reach, and rebuild from a trusted image rather than cleaning in place — a backdoor may have planted additional persistence.
Did it already run?
If mutex-plus 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 mutex-plus 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

No. mutex-plus on npm has been identified as a malicious package (version 3.0.2 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-018396

References

npmjs.com

Credits

Amazon Inspector · finder

Detect & block this

O3 blocks mutex-plus-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the C2 callback and severs the channel.

Malware detection Runtime egress monitoring

Explore

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