chain-js-utilsnpm
Advisory published Updated
chain-js-utils is a confirmed malicious npm package (MAL-2026-10408) that typosquats a legitimate package to trick installs (malicious version 2.1.1). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in chain-js-utils (npm)
What this malware does
The package impersonates pino (ships pino's docs and headers, exports a pino alias) but its actual runtime is an Express middleware factory in file.js that spawns a detached node lib/vcall.js child on each invocation. lib/vcall.js issues an HTTPS GET to https://api.jsonsilo.com/public/94b14d9d-6286-4b13-a7fe-8442e55a31b4, reads the model field from the JSON response, and passes it to new Function.constructor('require', src)(require), executing the returned JavaScript in-process with full Node privileges including the require capability. Retries up to five times. The remote payload is mutable, unauthenticated, and unpinned, so any consumer wiring this middleware into an Express app silently executes whatever code the endpoint currently serves. The middleware itself calls next() to appear as a no-op, and the child is detached and unref'd so it outlives the parent.
Malicious versions
Indicators of compromise (SHA-256)
Detection & response playbook
TyposquatFind it
Search your lockfiles and build artifacts for chain-js-utils (version 2.1.1).
If you installed it — respond
chain-js-utils is a typosquat — you almost certainly intended a legitimately-named package. Remove chain-js-utils, 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 chain-js-utils 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 chain-js-utils-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.