chai-as-forgetednpm
Advisory published Updated
chai-as-forgeted is a confirmed malicious npm package (MAL-2026-6219) that opens a backdoor for remote access (malicious version 9.24.6). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in chai-as-forgeted (npm)
What this malware does
Package name impersonates the popular chai-as-promised assertion library, but its package.json description and keywords are copied from pino and the code is unrelated to chai. The package's main entry exports a middleware factory that spawns lib/caller.js as a detached node child process. lib/caller.js base64-decodes a hardcoded URL pointing at api.jsonstorage.net (a mutable third-party JSON storage service), GETs the JSON document, extracts the cookie field, and executes its contents via new Function.constructor('require', s)(require) with full access to require. The C2 URL and request headers are stored as base64 strings inside a locally redefined process object that shadows the real process global, then decoded with atob at runtime. Any consumer who installs and invokes the exported middleware triggers arbitrary attacker-controlled code execution; the attacker can rotate the payload served by the JSON storage endpoint at will.
Malicious versions
Indicators of compromise (SHA-256)
Detection & response playbook
Backdoor / remote accessFind it
Search your lockfiles and build artifacts for chai-as-forgeted (version 9.24.6).
If you installed it — respond
chai-as-forgeted 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-forgeted 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
Campaign
References
Credits
- Amazon Inspector · finder
Detect & block this
O3 blocks chai-as-forgeted-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the C2 callback and severs the channel.