jest-test-plugin-utilsnpm
Advisory published Updated
jest-test-plugin-utils is a confirmed malicious npm package (MAL-2026-5896) that executes malicious code on install (malicious versions 1.0.0, 1.0.1, 1.0.2…). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in jest-test-plugin-utils (npm)
What this malware does
The package advertises itself as a Jest plugin (name: 'jest-test-plugin-utils', description: 'mqtt utils') but ships no Jest or MQTT functionality. Its main entry dist/index.js is a heavily obfuscated 200KB browserify bundle (obfuscator.io fingerprint: 1299-entry rotated string array, decoder wrapper, control-flow flattening; built with the declared devDependency 'gulp-javascript-obfuscator'). After deobfuscation, the only meaningful behavior is a function loadFilbetScriptSilently() (exposed as window.fetchFilbetScript) that creates a <script> element with src='https://cdn.jsdelivr.net/gh/gongben2024/network-security@main/src/filbet.js' and appends it to document.head, executing whatever code the author hosts at that mutable @main branch. The destination repository is named 'network-security' under author 'gongben2024' and is unrelated to the package's stated purpose. Because the reference is to the @main branch (not a pinned commit/tag), the author can change the executed payload at any time without republishing this package. Any application that bundles or imports this module will execute attacker-controlled JavaScript in the browser context, with full access to the host page's DOM, cookies, and storage. The combination of name camouflage, heavy obfuscation, and unpinned remote-script execution is a deliberate supply-chain attack pattern.
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 jest-test-plugin-utils (5 malicious versions).
If you installed it — respond
Remove jest-test-plugin-utils 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 jest-test-plugin-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 jest-test-plugin-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.