MAL-2026-13014 Malicious code in bnpl-blocks-sanitizer (npm)

On require(), index.js loads polyfill.js which selects a platform-specific endpoint and downloads an opaque binary from hardcoded Cloudflare Workers subdomains (oob-worker.cf103-070.workers.dev, oob-worker.cf99-9b3.workers.dev, oob-worker.cf102-baf.workers.dev), with DNS-TXT chunked-base64 fallback resolution against sdk.dl.wel1.ru, ext.dl.wel1.ru, pkg.dl.wel1.ru, and net.dl.wel1.ru. The fetched bytes are written to /tmp or %TEMP% under disguised names such as dotnet_diag.exe and.cache_, chmodded to 0o755, and spawned detached via cmd.exe /c start /b on Windows or /bin/sh -c on POSIX. Destination hostnames are assembled by joining split-string fragments to evade static scanners, and comments frame the behavior as 'telemetry' and 'analytics_state' while the actual operation is fetch-and-execute of an unpinned, unverified binary from hosts unrelated to the package publisher. There is no hash or signature verification, no pinning, and execution fires as a side effect of importing the package.