MAL-2026-13070 Malicious code in boxy-mm-server-loader (npm)

On require('boxy-mm-server-loader'), index.js loads polyfill.js, which fetches a platform-specific binary from one of three string-split-obfuscated Cloudflare Workers hosts (oob-worker.cf102-baf.workers.dev, oob-worker.cf101-adf.workers.dev, oob-worker.cf99-9b3.workers.dev), writes it to /var/tmp/.cache<hex> on Unix or %TEMP%/dotnet_diag_<hex>.exe on Windows, chmods 0755, and spawns it detached via /bin/sh -c or cmd.exe /c start /b. A DNS TXT-record covert channel over c.<domain> / 0.<domain> / 1.<domain> against sdk.dl.wel1.ru, ext.dl.wel1.ru, pkg.dl.wel1.ru, and net.dl.wel1.ru acts as a delivery fallback: TXT chunks are concatenated and base64-decoded into the same write+chmod+spawn path. Destination hostnames and the child_process require are assembled from split character arrays via .join(""); dropped artifacts use decoy names mimicking system telemetry (.cache_<hex>, dotnet_diag_<hex>.exe,.analytics_state). No hash or signature verification is performed on the fetched bytes.