Two fake npm packages are impersonating Rollup polyfill tools. Their real goal? Stealing your credentials and opening a backdoor to your machine.
JFrog researchers found the packages — “rollup-packages-polyfill-core” and “rollup-runtime-polyfill-core” — mimicking the legitimate rollup-plugin-polyfill-node project. The names, descriptions, and repository metadata all look convincing at a glance.
But the deception runs deeper. The first package installs “swift-parse-stream” as a second stage. The other pulls in “quirky-token.” Those are SVG utilities that connect to JSONKeeper to fetch and execute JavaScript malware. The whole chain uses layered obfuscation — hidden install-time execution, environment checks, credential theft.
The final payload connects to server 216.126.236[.]244 for an encrypted script that installs remote access tools. It can run terminal commands, capture screenshots, move the mouse, click, scroll, type, and steal browser data plus cryptocurrency wallet info. Windows-specific features include keyboard emulation via the @nut-tree-fork/nut-js package.
This isn’t a first. In April 2026, Panther detailed a campaign where 108 malicious npm packages spread BeaverTail and OtterCookie malware — including a package called “rollup-plugin-polyfill-route.” The overlap with OtterCookie’s capabilities is clear.
JFrog warns these targets are valuable. Rollup plugins load from config files, dev workstations, and CI jobs — all places packed with source code, npm tokens, Git credentials, cloud keys, SSH keys, and project secrets.
Four other packages were part of this campaign: quirky-token, react-icon-svgs, rollup-plugin-polyfill-connect, and swift-parse-stream. All have been removed from the npm registry.
