react-ui-polyfillsnpm
Malicious code in react-ui-polyfills (npm) Remove it immediately and rotate any exposed credentials.
What this malware does
Package advertises itself as React polyfills / UI compatibility helpers but ships no React or polyfill code. The exported getPlugin() function returns a closure that fetches JSON from https://jsonkeeper.com/b/GMIHS (an anonymous, mutable paste-style host with no integrity verification) and passes the parsed.cookie field directly to eval(), executing attacker-controlled JavaScript in the consumer's process. The mismatch between the package's advertised purpose (React polyfills) and its actual contents (SVG utilities + remote-eval backdoor) indicates the name is engineered to lure React developers. Any application that imports this package and invokes getPlugin() will execute whatever JavaScript the attacker chooses to host at the jsonkeeper URL at that moment.
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
Backdoor / remote accessFind it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for react-ui-polyfills (2 malicious versions). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging react-ui-polyfills across your stack and pipelines.
If you installed it — respond
react-ui-polyfills 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 react-ui-polyfills was ever installed, its post-install/runtime payload may have already executed. O3's L7 egress monitoring and runtime eBPF sensors detect the credential exfiltration or command-and-control callback after install and block the malicious outbound channel, so you catch and contain the actual compromise — not just the presence of the package.
How O3 protects you
O3 blocks react-ui-polyfills before install through its supply-chain scanner, and if it has already run, detects and severs the exfiltration or C2 callback at runtime through L7 egress monitoring and eBPF.
Frequently asked questions
Campaign
References
Credits
- Amazon Inspector · finder
Detect & block this
O3 blocks react-ui-polyfills-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the C2 callback and severs the channel.