xnder-wrapper-modulenpm
Malicious code in xnder-wrapper-module (npm) Remove it immediately and rotate any exposed credentials.
What this malware does
package.json declares "postinstall": "node scripts/script.js", causing scripts/script.js to run automatically on every npm install. That file is the package's only functional code and is heavily obfuscated (obfuscator.io string-array with a 242-entry rotated table, RC4 decoder String.fromCharCode(l.charCodeAt(t) ^ n[(n[r]+n[o])%256]), control-flow flattening, webpack-bundled across 5 modules requiring path/os/fs/child_process and an HTTP client). The decoded flow constructs a URL via string concatenation tricks (repeat('.'), concat('.')), performs an HTTPS GET, writes the response body to a file under os.tmpdir() via fs.writeFileSync(..., {flag:'w+'}), and then runs execSync(..., {windowsHide:true, cwd: os.tmpdir()}) against the dropped file — the standard fetch/drop/execute dropper shape with a sandbox-evasion flag. The package ships no other functionality; the README explicitly tells users the payload is unreviewed and recommends running it only inside a VM/Docker. Installing this package on a default npm install runs attacker-controlled code on the developer's machine.
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 xnder-wrapper-module (3 malicious versions). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging xnder-wrapper-module across your stack and pipelines.
If you installed it — respond
Remove xnder-wrapper-module 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 xnder-wrapper-module 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 xnder-wrapper-module 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 xnder-wrapper-module-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.