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Malicious package

simple-node-calc-bnpm

Advisory published Updated

simple-node-calc-b is a confirmed malicious npm package (MAL-2026-6453) 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 simple-node-calc-b (npm)

MAL-2026-6453
Immediate action
Remove the package, then rotate any secrets the build/runtime could reach.
npm uninstall simple-node-calc-b

What this malware does

[email protected] ships a binding.gyp that includes a modules file declaring "lodash": "<!(node lodash-compiler.js)". The gyp <!(...) syntax executes shell commands at parse time, and npm auto-invokes node-gyp on any package containing binding.gyp during npm install, so node lodash-compiler.js runs automatically on every install with no user opt-in. lodash-compiler.js is an 87KB obfuscator.io-style packed script (524-entry rotated string array _0x2f6e, decoder wrapper, control-flow flattening switch/case dispatcher, hex variable names) reachable through this auto-execution path. The script body contains require('fs').writeFileSync(...) along with string-array fragments 'poc.txt', 'Security P', 'OC.', 'writeFileS', 'ync' — self-describing as a proof-of-concept payload. The package name advertises a calculator; there is no legitimate reason for a calculator to ship 87KB of obfuscated code behind a hidden gyp shell-expansion. The combination of auto-execution on default install, heavy obfuscation, purpose mismatch, and self-described POC payload matches the canonical install-time RCE pattern.

Malicious versions

1 flagged
1.0.0

Indicators of compromise (SHA-256)

78b115418f82ef73f995f3bf6b0cb8bf50da516b56c691b76ccb939491d2b046

Detection & response playbook

Malicious package

  1. Find it

    Search your lockfiles and build artifacts for simple-node-calc-b (version 1.0.0).

  2. If you installed it — respond

    Remove simple-node-calc-b 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.

  3. Did it already run?

    If simple-node-calc-b 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. simple-node-calc-b 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-2026-007504

References

Credits

  • Amazon Inspector · finder

Detect & block this

O3 blocks simple-node-calc-b-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

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simple-node-calc-b (npm) malicious package — MAL-2026-6453 | O3 Security