Which versions of chai-as-built are malicious?

The following npm versions of chai-as-built are flagged malicious: 6.0.3. Treat any of these as compromised.

How do I remediate chai-as-built if I installed it?

chai-as-built 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 chai-as-built — how do I know if it already compromised me?

If chai-as-built 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 chai-as-built part of a known attack campaign?

Yes — chai-as-built is associated with the IN-MAL-2026-007523 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 chai-as-built 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 chai-as-built (version 6.0.3). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging chai-as-built across your stack and pipelines.

Malicious package

chai-as-builtnpm

chai-as-built is a confirmed malicious npm package (MAL-2026-6465) that opens a backdoor for remote access (malicious version 6.0.3). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in chai-as-built (npm)

MAL-2026-6465

Immediate action

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

npm uninstall chai-as-built

What this malware does

chai-as-built masquerades as the pino logger (package.json keywords 'fast','logger','stream','json'; file layout lib/proto.js, lib/redaction.js, lib/transport.js, lib/multistream.js, lib/levels.js; export module.exports.pino = middleware) while its name shadows the popular chai-as-promised. When a consumer imports the package and invokes the exported middleware, index.js spawns a detached node child process running lib/initializeCaller.js. That script base64-decodes a hardcoded URL (https://amethyst-lorrin-26.tiiny.site/index.json) hidden inside a fake process.env shadow object, GETs the JSON with a custom header, and passes the response's cookie field to new Function.constructor('require', response), then invokes the resulting function with require — executing arbitrary attacker-supplied JavaScript with full Node privileges. The fetch is retried up to 5 times against a mutable anonymous tiiny.site host with no integrity check. The combination of typosquat/impersonation cover, base64 string concealment of the C2 endpoint, detached child-process execution, and dynamic Function-constructor evaluation of remote content is a textbook supply-chain dropper.

Malicious versions

1 flagged

6.0.3

Indicators of compromise (SHA-256)

469c5ebe97d1e69d080295000d723febbb06050f65aed9a0f44a76fd707c0b1e

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 chai-as-built (version 6.0.3). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging chai-as-built across your stack and pipelines.
If you installed it — respond
chai-as-built 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 chai-as-built 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 chai-as-built 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. chai-as-built on npm has been identified as a malicious package (version 6.0.3 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-007523

References

npmjs.com

Credits

Amazon Inspector · finder

Detect & block this

O3 blocks chai-as-built-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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