chai-assertions-plusnpm
chai-assertions-plus is a confirmed malicious npm package (MAL-2026-12349) that executes malicious code on install (malicious versions 6.0.5, 6.0.6). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in chai-assertions-plus (npm)
What this malware does
The package is published as a Chai assertions extension, but the shipped code in index.js and lib/ is unrelated Pino logger source used as filler. Requiring the package loads lib/initializeCaller.js, which runs a top-level IIFE that shadows the global process object with a fake object whose env fields hold base64-encoded strings. At runtime those strings are atob-decoded to reconstruct a destination URL (https://amethyst-lorrin-26.tiiny.site/index.json) and an HTTP header name/value pair, an axios GET is issued to that URL, and the returned response body is passed into new Function("require", response) and invoked with the real require. This gives whoever controls the tiiny.site subdomain arbitrary code execution on the installer's machine with the package's require capability, on every import of the module. The name/description mismatch and the endpoint/header obfuscation indicate deliberate deception rather than a misconfiguration.
Malicious versions
Indicators of compromise (SHA-256)
Detection & response playbook
Malicious packageFind it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for chai-assertions-plus (2 malicious versions). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging chai-assertions-plus across your stack and pipelines.
If you installed it — respond
Remove chai-assertions-plus from your project and lockfile, then assume any secrets accessible to the build or runtime were exposed: rotate API keys, tokens, and credentials, and audit for unexpected outbound activity or persistence.
Did it already run?
If chai-assertions-plus 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-assertions-plus 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
Campaign
References
Credits
- Amazon Inspector · finder
Detect & block this
O3 blocks chai-assertions-plus-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.