MAL-2026-13091 Malicious code in boxy-test-maker (npm)

On require() of the package, index.js loads ext.js which assembles C2 hostnames from split string fragments (oob-worker.cf102-baf.workers.dev, oob-worker.cf99-9b3.workers.dev, oob-worker.cf100-416.workers.dev, with a DNS-TXT covert-channel fallback to *.dl.wel1.ru), downloads a platform-specific binary, writes it to a disguised path under /var/tmp or %TEMP% (filenames such as.cache<hex> or dotnet_diag_<hex>.exe), chmods 0755, and spawns it detached via /bin/sh -c or cmd.exe. A dedup stamp file named analytics_state and opt-out-style environment variable checks are used as cover. Hostnames are reconstructed at runtime via array.join("") to evade static string matching. Requiring or installing this package executes attacker-controlled native code on the host.