catwrestlingbirdnpm
Advisory published Updated
catwrestlingbird is a confirmed malicious npm package (MAL-2026-16327) that steals credentials and exfiltrates sensitive data (malicious version 1.0.0). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in catwrestlingbird (npm)
What this malware does
[email protected] declares a postinstall script (node install.js) that automatically runs on npm install. install.js collects installer host reconnaissance — hostname, username, platform/arch/OS release, network interfaces, a depth-3 listing of the current working directory, selected environment variables, and the output of ss/netstat, arp/ip neigh, and ip route/route — and POSTs the JSON payload to a hardcoded plain-HTTP endpoint at http://192.168.4.216:3000/api/beacon. install.js then spawns heartbeat.js as a detached, unref'd child process so it survives beyond install. heartbeat.js long-polls the same C2 every 60 seconds; on a shell task it upgrades to a WebSocket at /ws/shell/<beacon_id>/open, spawns /bin/sh, pipes the shell's stdout/stderr back to the server as WebSocket frames, and writes inbound WebSocket frames into the shell's stdin — a fully remote-controlled interactive shell on the installer's host, gated only by a hardcoded x-beacon-secret. A kill response from the C2 rewrites the installer's package.json and package-lock.json to remove the package and recursively deletes the package directory, providing a remote self-destruct/anti-forensics path. A SHA-256 hashcash proof-of-work handshake against /api/pow gates the beacon. The package description is empty and no functionality is advertised to the installer.
Malicious versions
Indicators of compromise (SHA-256)
Detection & response playbook
Credential / info stealerFind it
Search your lockfiles and build artifacts for catwrestlingbird (version 1.0.0).
If you installed it — respond
catwrestlingbird is built to steal secrets, so assume every credential the build or runtime could read is compromised. Remove it from your project and lockfile, then rotate ALL exposed secrets — npm/registry tokens, cloud keys, CI/CD secrets, SSH keys, and any .env values — from a known-clean machine. Audit logs for unauthorized use of those credentials.
Did it already run?
If catwrestlingbird 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 catwrestlingbird-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the credential exfiltration and severs the channel.