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Malicious package

calculator-preinstall-hook-demonpm

Advisory published Updated

calculator-preinstall-hook-demo is a confirmed malicious npm package (MAL-2026-18454) that executes malicious code on install (malicious version 1.1.2). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in calculator-preinstall-hook-demo (npm)

MAL-2026-18454
Immediate action
Remove the package, then rotate any secrets the build/runtime could reach.
npm uninstall calculator-preinstall-hook-demo

What this malware does

[email protected] presents itself as a test fixture for npm lifecycle hooks. Its preinstall script runs node preinstall.js on npm install, which POSTs the machine's hostname and the OS username to the Discord webhook https://discord.com/api/webhooks/1566215853794394162/xsqpEbSn-cc3DU2AKWdzqWnXX5hjTfV-gUePQZ4evrHGlZctMd40TKCrN42qnJd7moc1. It was published by the npm account bigdevin55 together with [email protected], which pulls it in as a dependency.

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.

Malicious versions

1 flagged
1.1.2

Indicators of compromise (SHA-256)

db06ea25b6b764475357882b39d46919c5c083785f24d7ab2a264085acb01d81

Detection & response playbook

Malicious package

  1. Find it

    Search your lockfiles and build artifacts for calculator-preinstall-hook-demo (version 1.1.2).

  2. If you installed it — respond

    Remove calculator-preinstall-hook-demo 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 calculator-preinstall-hook-demo 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. calculator-preinstall-hook-demo on npm has been identified as a malicious package (version 1.1.2 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

GHSA-c6pj-8fr8-qq3c

References

Credits

  • InvisiRisk, Inc. · finder

Detect & block this

O3 blocks calculator-preinstall-hook-demo-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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calculator-preinstall-hook-demo (npm) malicious package — MAL-2026-18454 | O3 Security