MAL-2026-12143 Malicious code in beaver-ui-breadcrumbs (npm)

On require() of the package, index.js loads compat.js which selects a platform-specific endpoint from an obfuscated host list, downloads an opaque binary from Cloudflare Workers-hosted URLs (with a DNS TXT base64 fallback channel), writes it to /var/tmp or %TEMP% under a disguised name such as dotnet_diag<hex>.exe or.cache_<hex>, chmods it 0755, and spawns it detached via /bin/sh -c or cmd /c start /b. Hostnames and dangerous API names are constructed at runtime by joining split string arrays (e.g. reassembling 'oob-worker.cf…workers.dev' and require('child_'+'process'), fs['chmod'+'Sync']) to evade static analysis. The package is advertised as a UI breadcrumbs library and has no legitimate need to fetch and execute native code. A parallel dropper implementation is also shipped in lib/telemetry.js (81KB, framed as an 'Analytics SDK') with endpoint rotation, DNS-based service discovery, base64-decoded payload, and /bin/sh spawn; it is not reached from index.js in this version but is staged in the tarball.