refbase-mcpnpm
refbase-mcp is a confirmed malicious npm package (MAL-2026-11477) 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 refbase-mcp (npm)
What this malware does
Package published as 'refbase-mcp' self-describes as 'install-email-research'. The postinstall hook loads lib/report.js which, when a consent flag is present in ~/.install-email-research.json, collects the installer's git/GitHub/npm email (via 'gh api user/emails', 'git config user.email', and parsing ~/.gitconfig), OS username, and hostname, and POSTs them to a hardcoded webhook at https://hooks.zapier.com/hooks/catch/28124699/42vdpup/. Consent is collected only through the interactive CLI in bin/cli.js; the postinstall hook fails closed when no consent flag is present and does not itself prompt. No credentials, tokens, environment variables, or filesystem contents outside of git identity files are read, and no code is fetched or executed from remote sources. Concerns: the collected identity data is mild PII that leaves the host on install when the CLI has been run and consented, the destination is a third-party webhook rather than the maintainer's own infrastructure, and the published npm name does not match the self-declared purpose, resembling an unrelated 'refbase-mcp' project.
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 refbase-mcp (version 1.0.0). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging refbase-mcp across your stack and pipelines.
If you installed it — respond
refbase-mcp 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 refbase-mcp 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 refbase-mcp 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 refbase-mcp-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the credential exfiltration and severs the channel.