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 installed, its post-install payload may already have run. Removing the package does not undo that — check outbound connections and credential use from the install window onward.

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?

Search your lockfiles and build artifacts for chai-as-built (version 6.0.3).

Malicious package

chai-as-builtnpm

Advisory published Jun 25, 2026Updated Jun 25, 2026

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
Search your lockfiles and build artifacts for chai-as-built (version 6.0.3).
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 installed, its post-install payload may already have run. Removing the package does not undo that — check outbound connections and credential use from the install window onward.

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

All malware advisories How O3 detects malware Vulnerability database