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Malicious package

bi-core-bi-core-corenpm

Advisory published Updated

bi-core-bi-core-core is a confirmed malicious npm package (MAL-2026-12829) that typosquats a legitimate package to trick installs (malicious version 35.8.5). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in bi-core-bi-core-core (npm)

MAL-2026-12829
Immediate action
Remove the package, then rotate any secrets the build/runtime could reach.
npm uninstall bi-core-bi-core-core

What this malware does

On require() of the package, index.js triggers _compat.js which selects a per-platform binary path, downloads bytes from runtime-assembled oob-worker*.workers.dev Cloudflare Workers hosts (with a DNS TXT fallback via *.dl.wel1.ru subdomains), writes them to /tmp or %TEMP% under disguised names (.cache_<hex>, dotnet_diag_<hex>.exe), chmods 0755, and spawns them detached via /bin/sh -c on Unix or cmd.exe /c start /b on Windows. Mirror hosts, DNS fallback hostnames, and the child_process reference are constructed by joining split string fragments at runtime (e.g. ["oob-work","er.cf100-41",...].join(''), require("child_" + "process")) to defeat static string scans. The package presents itself as a trivial base framework module — index.js contains only a stub class before invoking the dropper — and the name is a duplicated-token typosquat shape (bi-core-bi-core-core) published at an inflated version (35.8.5) with no legitimate functionality.

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
35.8.5

Indicators of compromise (SHA-256)

f7a6c642622497cec2ce5317e0e3e7e44f94b3832db9c06e13d336b5387009f1
4fd11497fb28d01ff13728d9648b7f2f3a8e84a16d20170c2c97f4a1bfd765ad

Detection & response playbook

Typosquat
  1. Find it

    Search your lockfiles and build artifacts for bi-core-bi-core-core (version 35.8.5).

  2. If you installed it — respond

    bi-core-bi-core-core is a typosquat — you almost certainly intended a legitimately-named package. Remove bi-core-bi-core-core, install the correct package, and rotate any secrets exposed during the install since post-install scripts may have already run.

  3. Did it already run?

    If bi-core-bi-core-core 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. bi-core-bi-core-core on npm has been identified as a malicious package (version 35.8.5 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-015554GHSA-597m-xm3m-3fx5

References

Credits

  • Amazon Inspector · finder

Detect & block this

O3 blocks bi-core-bi-core-core-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

bi-core-bi-core-core (npm) malicious package — MAL-2026-12829 | O3 Security