0ctf-chalwebnpm
Advisory published Updated
0ctf-chalweb is a confirmed malicious npm package (MAL-2026-3667) 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 0ctf-chalweb (npm)
What this malware does
The package's entire content (xss.js) is a 2-line cookie-stealing payload that creates an Image element pointing to https://collaborator.gbrls.workers.dev/ with base64-encoded document.cookie appended. This is a textbook XSS cookie exfiltration primitive targeting an attacker-controlled Cloudflare Workers endpoint. Regardless of whether this was published as a CTF artifact, any consumer who installs and bundles this package into a web app will exfiltrate end-users' cookies. There is no legitimate use case for publishing a cookie-exfil snippet to the public npm registry.
Malicious versions
Indicators of compromise (SHA-256)
Detection & response playbook
Credential / info stealerFind it
Search your lockfiles and build artifacts for 0ctf-chalweb (version 1.0.0).
If you installed it — respond
0ctf-chalweb 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 0ctf-chalweb 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 0ctf-chalweb-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the credential exfiltration and severs the channel.