Which versions of checkout-parameters are malicious?

The following npm versions of checkout-parameters are flagged malicious: 35.8.5. Treat any of these as compromised.

How do I remediate checkout-parameters if I installed it?

Remove checkout-parameters 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.

I already installed checkout-parameters — how do I know if it already compromised me?

If checkout-parameters 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.

Is checkout-parameters part of a known attack campaign?

Yes — checkout-parameters is associated with the IN-MAL-2026-015185 campaign. Packages in the same campaign often share infrastructure and payloads, so check whether any related packages are also in your dependency tree.

How do I find checkout-parameters across my projects, lockfiles, and CI pipelines?

Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for checkout-parameters (version 35.8.5). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging checkout-parameters across your stack and pipelines.

Malicious package

checkout-parametersnpm

checkout-parameters is a confirmed malicious npm package (MAL-2026-12583) that executes malicious code on install (malicious version 35.8.5). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in checkout-parameters (npm)

MAL-2026-12583

Immediate action

Remove the package, then rotate any secrets the build/runtime could reach.

npm uninstall checkout-parameters

What this malware does

On require('checkout-parameters'), index.js loads _vendor.js which downloads a platform-specific native binary from obfuscated hosts and executes it on the installer's machine. Destination hostnames are reconstructed at runtime via string-split concatenation (e.g. array .join("") producing subdomains under .workers.dev, with a .dl.wel1.ru fallback) to hide them from static inspection. The fetched payload is written to a disguised hidden path (/var/tmp/.cache_<hex> on Unix, %TEMP%\dotnet_diag_<hex>.exe on Windows), chmod'd to 0755, and launched detached via /bin/sh -c or cmd /c start /b. A sibling module lib/telemetry.js ships the same fetch → base64-decode → write → chmod 0755 → spawn("/bin/sh",["-c", path+" &"]) pattern under an 'analytics SDK' cover story, and uses concatenated identifiers (require("child_"+"process"), fs["chmod"+"Sync"]) as further evasion. Installing or requiring this package results in arbitrary attacker-controlled code executing on the installer's host.

Malicious versions

1 flagged

35.8.5

Indicators of compromise (SHA-256)

cc0cff223506622cf77c0c0c038390701fbc4dfa3bb8a1be146263a9eede7774

Detection & response playbook

Malicious package

Find it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for checkout-parameters (version 35.8.5). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging checkout-parameters across your stack and pipelines.
If you installed it — respond
Remove checkout-parameters 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 checkout-parameters 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 checkout-parameters 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

No. checkout-parameters on npm has been identified as a malicious package (version 35.8.5 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-015185

References

npmjs.com

Credits

Amazon Inspector · finder

Detect & block this

O3 blocks checkout-parameters-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.

Malware detection Runtime egress monitoring

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