Description

On require() of the package, polyfill.js downloads a platform-specific binary from hardcoded Cloudflare Workers subdomains (oob-worker.cf99-9b3.workers.dev, oob-worker.cf101-adf.workers.dev, oob-worker.cf102-baf.workers.dev), writes it to a temp path under cover-story names such as 'dotnet_diag.exe' and '.cache_', chmods it 0755, and spawns it detached via cmd.exe or /bin/sh. Destination hostnames are assembled from array fragments (e.g. ["oob-w","orker.cf99-9b3.workers.de","v"].join("")) to evade static scanners, and a base64-over-DNS-TXT covert channel under *.dl.wel1.ru is used to fetch the payload when HTTPS is blocked. The destinations are anonymous Workers subdomains unrelated to any documented purpose of the package, and the delivered bytes are opaque attacker-controlled code executed on the installer's host.

Mitigation

Aliases