new-ecro-helpernpm
Advisory published Updated
new-ecro-helper is a confirmed malicious npm package (MAL-2026-6283) that executes malicious code on install (malicious version 5.8.0). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in new-ecro-helper (npm)
What this malware does
The package publishes verbatim big.js v7.0.1 source (including the upstream copyright header, README, repository URL pointing to MikeMcl/big.js, and the upstream author's email) under the unrelated name new-ecro-helper. The main entry (big.js / big.mjs) has an injected loader block that runs on every require('new-ecro-helper'): try { const doc = require("new-helper"); doc.from_str().then(...).catch(...) } catch (error) { }. The dependency new-helper is declared as ^5.8.1 in package.json, so the semver caret admits any current or future 5.x.y version of that sibling package as the actual delivered payload. All errors from both the require and the invocation are swallowed by empty catch handlers, hiding the activity from the consuming application. The big.js code itself is unmodified and serves only as a cover library to disguise the loader. The net effect on installers: npm install new-ecro-helper pulls new-helper into the dependency tree, and any consumer that requires the package immediately and silently executes code in that sibling package.
Any computer that has this package installed or running should be considered fully compromised. All secrets and keys stored on that computer should be rotated immediately from a different computer. The package should be removed, but as full control of the computer may have been given to an outside entity, there is no guarantee that removing the package will remove all malicious software resulting from installing it.
Malicious versions
Indicators of compromise (SHA-256)
Detection & response playbook
Malicious packageFind it
Search your lockfiles and build artifacts for new-ecro-helper (version 5.8.0).
If you installed it — respond
Remove new-ecro-helper 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 new-ecro-helper 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 new-ecro-helper-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.