MAL-2026-12179 Malicious code in fb-insurance--boxified-form-vzr-test (npm)

On require of the package, index.js loads _loader.js which selects a platform-specific endpoint, fetches an executable payload over HTTPS from hardcoded Cloudflare Workers hosts (oob-worker.cf99-9b3.workers.dev, cf100-416.workers.dev, cf103-070.workers.dev), writes it to /var/tmp or %TEMP% under a deceptive filename (.cache_<hex> on POSIX, dotnet_diag_<hex>.exe on Windows), chmods it 0755, and spawns it detached-and-unref'd via /bin/sh -c or cmd. If the HTTPS mirrors fail, _loader.js falls back to a DNS-TXT covert channel: it resolves c.<domain> for a chunk count against resolvers under *.dl.well1.site (tin/tina/ldr/win subdomains) and reassembles N base64 TXT fragments from <i>.<domain> into the same executable buffer. Destination hostnames and resolver domains are constructed at runtime by joining short substring arrays (e.g. ['oob-worker.cf99-9b3','.worker','s.dev'].join('')) to evade static string matching. No hash or signature is verified on the fetched bytes. The fetched executable runs with the installer's privileges.