markdownlint-cli2-fixnpm
Malicious code in markdownlint-cli2-fix (npm) Remove it immediately and rotate any exposed credentials.
What this malware does
Package name 'markdownlint-cli2-fix' impersonates the popular 'markdownlint-cli2' linter but contains no linter functionality — the README states 'Takeover By lobo / For POC only' and the package ships only postinstall.js plus metadata. postinstall.js (line 30) hardcodes BURP_COLLABORATOR_URL = "http://i0jvc03bvcjt40q39f5fx8671y72vxjm.oastify.com" and, when run, collects host/network reconnaissance (os.hostname(), username, network interfaces, disk info, AD domain info, full process list via ps aux/tasklist through execSync), enumerates Object.keys(process.env) matching a curated credential list (AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY, GITHUB_TOKEN, NPM_TOKEN, STRIPE_SECRET, SSH_PRIVATE_KEY, DEPLOY_KEY, SLACK_TOKEN, DISCORD_TOKEN, JWT_SECRET) plus regex /_(TOKEN|SECRET|KEY|PASSWORD|PWD|APIKEY|API_KEY|PRIVATE_KEY)$/i, and POSTs the JSON payload to the attacker-controlled Burp Collaborator endpoint at oastify.com. While package.json in this version does not declare a scripts.postinstall hook (so the file does not auto-execute on npm install), the package is a deliberate typosquat with no legitimate purpose, the exfiltration code is fully functional, and any installer who is tricked into running the file — or any republish that wires the lifecycle hook — produces immediate credential exfiltration.
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
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for markdownlint-cli2-fix (2 malicious versions). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging markdownlint-cli2-fix across your stack and pipelines.
If you installed it — respond
markdownlint-cli2-fix 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 markdownlint-cli2-fix was ever installed, its post-install/runtime payload may have already executed. O3's L7 egress monitoring and runtime eBPF sensors detect the credential exfiltration or command-and-control callback after install and block the malicious outbound channel, so you catch and contain the actual compromise — not just the presence of the package.
How O3 protects you
O3 blocks markdownlint-cli2-fix before install through its supply-chain scanner, and if it has already run, detects and severs the exfiltration or C2 callback at runtime through L7 egress monitoring and eBPF.
Frequently asked questions
Campaign
References
Credits
- Amazon Inspector · finder
Detect & block this
O3 blocks markdownlint-cli2-fix-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the credential exfiltration and severs the channel.