vitest-agentnpm

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.