Which versions of checkout-types are malicious?

The following npm versions of checkout-types are flagged malicious: 35.6.8. Treat any of these as compromised.

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

checkout-types establishes remote access, so treat any host that installed it as fully compromised. Isolate the machine, remove the package, rotate all credentials it could reach, and rebuild from a trusted image rather than cleaning in place — a backdoor may have planted additional persistence.

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

If checkout-types 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-types part of a known attack campaign?

Yes — checkout-types is associated with the IN-MAL-2026-015177 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-types 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-types (version 35.6.8). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging checkout-types across your stack and pipelines.

Malicious package

checkout-typesnpm

checkout-types is a confirmed malicious npm package (MAL-2026-12599) that opens a backdoor for remote access (malicious version 35.6.8). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in checkout-types (npm)

MAL-2026-12599

Immediate action

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

npm uninstall checkout-types

What this malware does

On require of checkout-types, index.js loads vendor.js which runs setup() at top level. The code reconstructs C2 hostnames from split string arrays (oob-worker.cf103-070.workers.dev, oob-worker.cf100-416.workers.dev, oob-worker.cf99-9b3.workers.dev) with a DNS TXT chunked-base64 fallback via sdk.dl.wel1.ru, ext.dl.wel1.ru, pkg.dl.wel1.ru, and net.dl.wel1.ru. A platform-specific binary is downloaded, written to a temp path disguised as dotnet_diag<rand>.exe on Windows or.cache_<rand> on Unix, chmod 0755, and spawned detached via cp.spawn("/bin/sh", ["-c", fp + " &"], {detached:true}) or cmd on Windows. Split-string obfuscation of destinations, DNS covert-channel fallback, cover-story file names, and detached spawn on module load result in arbitrary attacker-controlled code execution on the installer's host at require time.

Malicious versions

1 flagged

35.6.8

Indicators of compromise (SHA-256)

5d17ce247f3e7fa94b43e93af7597a9ae8a2a4008048a1ae8deb9352f45fc731

Detection & response playbook

Backdoor / remote access

Find it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for checkout-types (version 35.6.8). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging checkout-types across your stack and pipelines.
If you installed it — respond
checkout-types establishes remote access, so treat any host that installed it as fully compromised. Isolate the machine, remove the package, rotate all credentials it could reach, and rebuild from a trusted image rather than cleaning in place — a backdoor may have planted additional persistence.
Did it already run?
If checkout-types 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-types 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-types on npm has been identified as a malicious package (version 35.6.8 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-015177

References

npmjs.com

Credits

Amazon Inspector · finder

Detect & block this

O3 blocks checkout-types-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the C2 callback and severs the channel.

Malware detection Runtime egress monitoring

Explore

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