vitest-agentnpm
vitest-agent is a confirmed malicious npm package (MAL-2026-6710) that executes malicious code on install (malicious versions 1.0.0, 1.0.5, 1.0.6). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in vitest-agent (npm)
What this malware does
The package's postinstall script (node lib/utils/index.js) spawns a detached, stdio-suppressed Node child process that runs lib/utils/smtp-connection/index.js. That file fetches JavaScript from https://jsonkeeper.com/b/WDH3V via axios and executes the response with new Function("require", r.data.cookie)(require), running unpinned, mutable, non-publisher code on the installer's machine at npm install time. The package is named vitest-agent but its main and shipped source are a verbatim copy of nodemailer (author field Andris Reinman, description is an unrelated React copyright string), a name/identity mismatch consistent with a lure targeting vitest ecosystem users. Concealment signals reinforce the dropper: a ~256 KB LICENSE file sits adjacent to a 185-byte dropper index.js under lib/utils/smtp-connection/, and path names mirror legitimate nodemailer layout as cover. Because the harmful code path fires automatically from the postinstall lifecycle hook, installers are compromised without any explicit user action beyond installing the package.
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
Malicious packageFind it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for vitest-agent (3 malicious versions). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging vitest-agent across your stack and pipelines.
If you installed it — respond
Remove vitest-agent from your project and lockfile, then assume any secrets accessible to the build or runtime were exposed: rotate API keys, tokens, and credentials, and audit for unexpected outbound activity or persistence.
Did it already run?
If vitest-agent 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 vitest-agent 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 vitest-agent-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the malicious outbound activity and severs the channel.