testis-packnpm
Malicious code in testis-pack (npm) Remove it immediately and rotate any exposed credentials.
What this malware does
package.json declares a preinstall hook (node index.js) that runs automatically on npm install. index.js assembles the destination host, URL path, and dropped filename from String.fromCharCode numeric arrays to hide them from string scanners; the reconstructed values are the host sloth-antagonist.vercel.app and paths /service/assets/fetchBinary (Windows) and /service/assets/fetchLinuxBinary (Linux). The script downloads the unpinned, unverified binary via https.get(...).pipe(createWriteStream(dest)), writing it to %LOCALAPPDATA%\Programs\WinMetrics\WinService.exe on Windows or ~/.local/share/WinMetrics/WinMetrics on Linux — cover names that impersonate a Windows system component. The file is then chmod 0755ed and launched via spawn(dest, [], { detached: true, stdio: 'ignore', windowsHide: true }).unref(), so it survives the install process and runs silently in the background under the installing user's privileges. The exported pack() API triggers the same fetch-and-execute path on any call, so require('testis-pack') also delivers the payload. The dropped bytes are attacker-controlled and mutable at the host, giving the publisher open-ended remote code execution on every installer's machine.
Malicious versions
Indicators of compromise (SHA-256)
Detection & response playbook
TyposquatFind it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for testis-pack (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 testis-pack across your stack and pipelines.
If you installed it — respond
testis-pack is a typosquat — you almost certainly intended a legitimately-named package. Remove testis-pack, install the correct package, and rotate any secrets exposed during the install since post-install scripts may have already run.
Did it already run?
If testis-pack 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 testis-pack 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 testis-pack-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.