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)
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
Indicators of compromise (SHA-256)
Detection & response playbook
TyposquatFind it
Search your lockfiles and build artifacts for bi-core-bi-core-core (version 35.8.5).
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.
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
Campaign
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.