The 'claims-block-visibility' npm package (version 35.3.8) includes a malicious payload embedded in its index.js file. Upon requiring the package, it loads a polyfill script that selects an OS-specific endpoint to download a binary from obfuscated hosts under the *.workers.dev domain. If HTTPS is unavailable, it falls back to a chunked base64-over-DNS-TXT retrieval method from several .ru domains. The downloaded binary is saved to a temporary file with a disguised name, given executable permissions, and executed detached from the parent process using masked child_process calls. This results in immediate fetch-and-execute of opaque attacker-controlled native code on any system that imports this package.

Any application or environment that requires this specific version of the 'claims-block-visibility' package will execute attacker-controlled native code automatically, potentially leading to full system compromise, data theft, or further malicious activity. The execution is silent and obscured, increasing the risk of undetected compromise.

No official patch or remediation is currently documented. Users should immediately avoid using version 35.3.8 of 'claims-block-visibility'. Remove this version from all environments and replace it with a trusted, verified version or alternative package. Monitor for any unauthorized execution of binaries and consider forensic analysis if this version was previously used.