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Malicious package

type-check-816dnpm

Malicious code in type-check-816d (npm) Remove it immediately and rotate any exposed credentials.

MAL-2026-6101
Immediate action
Remove the package, then rotate any secrets the build/runtime could reach.
npm uninstall type-check-816d

What this malware does

The package declares a postinstall hook ("postinstall": "node run.js") that runs run.js automatically on npm install. run.js imports os, https, http, and child_process, reads host identifiers and environment data (process.env.USER, os.hostname(), os.platform(), process.cwd()), base64-encodes the payload (Buffer.from(...).toString('base64')), and exfiltrates it via outbound HTTP/HTTPS requests (multiple POST calls and a GET). The package name appears to be a numeric-suffixed lure with no legitimate documented purpose, and the postinstall behavior is a credential/host-recon exfiltration pattern rather than any build or setup task. Installing this package causes immediate, unattended exfiltration of installer host data to an attacker-controlled endpoint.

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

1 flagged
1.0.0

Indicators of compromise (SHA-256)

6bd3f7912317a2b9465a4c22ea948951f70aaa8c0d12f152572d43febc5667dd
61d6a8d969f423b926400caee1087849fe0475b8ca302176004bfd5574e50e3d

Frequently asked questions

No. type-check-816d on npm has been identified as a malicious package (version 1.0.0 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-006963GHSA-q7qm-cfrq-fg6g

References

Credits

  • Amazon Inspector · finder

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Supply-chain protection
type-check-816d (npm) malicious package — MAL-2026-6101 | O3 Security