Which versions of express-chai are malicious?

The following npm versions of express-chai are flagged malicious: 3.7.9. Treat any of these as compromised.

How do I remediate express-chai if I installed it?

express-chai is a typosquat — you almost certainly intended a legitimately-named package. Remove express-chai, install the correct package, and rotate any secrets exposed during the install since post-install scripts may have already run.

I already installed express-chai — how do I know if it already compromised me?

If express-chai 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 express-chai part of a known attack campaign?

Yes — express-chai is associated with the IN-MAL-2026-016744 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 express-chai 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 express-chai (version 3.7.9). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging express-chai across your stack and pipelines.

Malicious package

express-chainpm

express-chai is a confirmed malicious npm package (MAL-2026-13446) that typosquats a legitimate package to trick installs (malicious version 3.7.9). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in express-chai (npm)

MAL-2026-13446

Immediate action

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

npm uninstall express-chai

What this malware does

express-chai presents itself as an Express logger middleware impersonating pino, but its exported middleware factory invokes lib/caller.js which decodes a base64-obfuscated URL (https://gray-dyane-31.tiiny.site/index.json) stored in lib/const.js, fetches a JSON payload via axios with a base64-encoded dev-secret-key header, and passes the response's cookie field to new Function.constructor("require", s), then invokes the resulting function with the local require. This grants the operator of the anonymous tiiny.site host arbitrary code execution inside the installer's Node.js process at middleware setup time, with full access to require and the surrounding application context. The destination URL and secret header are base64-encoded rather than plain configuration, and the package's naming, keywords (fast, logger, stream, json), and pino-mirroring script names disguise a remote code loader as a well-known logging library.

Malicious versions

1 flagged

3.7.9

Indicators of compromise (SHA-256)

34482e23635422fb5ca5632e68708453f1c99317a31e5e8346c75c4d3466560f

Detection & response playbook

Typosquat

Find it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for express-chai (version 3.7.9). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging express-chai across your stack and pipelines.
If you installed it — respond
express-chai is a typosquat — you almost certainly intended a legitimately-named package. Remove express-chai, install the correct package, and rotate any secrets exposed during the install since post-install scripts may have already run.
Did it already run?
If express-chai 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 express-chai 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. express-chai on npm has been identified as a malicious package (version 3.7.9 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-016744

References

npmjs.com

Credits

Amazon Inspector · finder

Detect & block this

O3 blocks express-chai-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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