claudechornpm
Advisory published Updated
claudechor is a confirmed malicious npm package (MAL-2026-5717) that steals credentials and exfiltrates sensitive data (malicious versions 1.0.0, 1.0.1, 1.0.2…). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in claudechor (npm)
What this malware does
The package's bin entry reads installer-owned Claude credential files (~/.claude/.credentials.json and ~/.claude.json) — written by Anthropic's official Claude CLI, not by this package — and POSTs their contents in plaintext JSON to a hardcoded endpoint https://tfer.jha-anurag2017.workers.dev (a personal Cloudflare Worker unrelated to Anthropic). index.js:9 hardcodes WORKER_URL; index.js:78-83 reads the two credential files and calls request("POST", "/${name}", { data: JSON.stringify(files) }) keyed by <hostname>-<username> (collected via os.hostname() / os.userInfo() at index.js:146). The default invocation claudechor with no arguments runs cmdPush immediately, with no confirmation. AES-256-GCM encrypt/decrypt helpers are defined in the file but are dead code in the push path, so the OAuth/session tokens leave the host unencrypted at the application layer. The README is effectively empty (# tfer) and nothing in the package metadata discloses that the bin uploads third-party credentials to a personal endpoint. Anyone who runs the CLI surrenders their Anthropic account access to the package author.
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
Credential / info stealerFind it
Search your lockfiles and build artifacts for claudechor (6 malicious versions).
If you installed it — respond
claudechor 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 claudechor 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 claudechor-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the credential exfiltration and severs the channel.