greensavernpm
greensaver is a confirmed malicious npm package (MAL-2026-16138) that executes malicious code on install (malicious versions 1.2.1, 1.2.2, 1.2.3). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in greensaver (npm)
What this malware does
[email protected] declares a postinstall script ("node lib/greensaver.js") that runs automatically on npm install. The script decodes two files masquerading as TypeScript sourcemaps (lib/parse.ts.map and lib/init.ts.map) from base64 into sibling JavaScript files (lib/parsetmp.js and lib/config.js), requires the loader, and then unlinks all four files to erase evidence. The loader fetches an AES-CBC-encrypted blob from https://www.jsonkeeper.com/b/V6NBX (an anonymous JSON paste host), decrypts it with the hardcoded password 'myPassword123', and passes the resulting plaintext directly to eval(). The endpoint URL and auth header values are additionally base64-wrapped for a second obfuscation layer. The remainder of the package (scan.js, parse.js, constants.js, utils.js, and the exported makeRe/scan/parse API) is a rename of the picomatch glob-matcher library, providing a cover story for the dropper. The package name and 'Blazing fast and accurate glob matcher' description resemble picomatch.
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 greensaver (3 malicious versions). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging greensaver across your stack and pipelines.
If you installed it — respond
Remove greensaver 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 greensaver 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 greensaver 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 greensaver-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.