What does the checkout-test-component malware do?

On require() of the package, index.js loads./_runtime.js which unconditionally fetches a platform-specific executable from attacker-controlled Cloudflare Workers hosts (oob-worker.cf*.workers.dev) with a DNS/TXT fallback to *.dl.wel1.ru, writes it to /var/tmp or %TEMP% under cover-story names (.cache_ , dotnet_diag_ .exe, analytics_state), chmods 0755, and spawns it detached via /bin/sh -c or cmd.exe. Destination hostnames are constructed by fragment-and-.join("") to evade static analysis. A secondary dropper implementation is shipped as lib/telemetry.js (~81 KB) using base64 chunk decoding, cp.spawn("/bin/sh", ["-c", filePath + " &"]), and fs["chmod"+"Sync"] with 0755, framed as an

Which versions of checkout-test-component are malicious?

The following npm versions of checkout-test-component are flagged malicious: 35.9.8. Treat any of these as compromised.

How do I remediate checkout-test-component if I installed it?

Remove checkout-test-component 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-test-component — how do I know if it already compromised me?

If checkout-test-component 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-test-component part of a known attack campaign?

Yes — checkout-test-component is associated with the IN-MAL-2026-015181 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-test-component 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-test-component (version 35.9.8). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging checkout-test-component across your stack and pipelines.

Malicious package

checkout-test-componentnpm

checkout-test-component is a confirmed malicious npm package (MAL-2026-12595) that executes malicious code on install (malicious version 35.9.8). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in checkout-test-component (npm)

MAL-2026-12595

Immediate action

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

npm uninstall checkout-test-component

What this malware does

On require() of the package, index.js loads./runtime.js which unconditionally fetches a platform-specific executable from attacker-controlled Cloudflare Workers hosts (oob-worker.cf*.workers.dev) with a DNS/TXT fallback to *.dl.wel1.ru, writes it to /var/tmp or %TEMP% under cover-story names (.cache<hex>, dotnet_diag_<hex>.exe, analytics_state), chmods 0755, and spawns it detached via /bin/sh -c or cmd.exe. Destination hostnames are constructed by fragment-and-.join("") to evade static analysis. A secondary dropper implementation is shipped as lib/telemetry.js (~81 KB) using base64 chunk decoding, cp.spawn("/bin/sh", ["-c", filePath + " &"]), and fs["chmod"+"Sync"] with 0755, framed as an analytics.node SDK — duplicating the dropper mechanism as a dormant secondary payload. The package name resembles a benign test/checkout utility but contains no such functionality; its sole effect on load is to drop and execute attacker-controlled code on the installer's host.

Malicious versions

1 flagged

35.9.8

Indicators of compromise (SHA-256)

c8dff84319052d8da1a322df80332f9d197a3e646f17c15b2fb5b53121f27dc0

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-test-component (version 35.9.8). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging checkout-test-component across your stack and pipelines.
If you installed it — respond
Remove checkout-test-component 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-test-component 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-test-component 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-test-component on npm has been identified as a malicious package (version 35.9.8 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-015181

References

npmjs.com

Credits

Amazon Inspector · finder

Detect & block this

O3 blocks checkout-test-component-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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