Description

On require of the package, index.js loads support.js which downloads a platform-specific binary from string-split-obfuscated hosts (oob-worker.cf103-070.workers.dev, oob-worker.cf99-9b3.workers.dev, oob-worker.cf101-adf.workers.dev), with a DNS TXT fallback that reassembles a base64 payload from numbered subdomains under dl.wel1.ru (sdk.dl.wel1.ru, ext.dl.wel1.ru, pkg.dl.wel1.ru, net.dl.wel1.ru). The fetched binary is written to /var/tmp on Unix or %TEMP% on Windows under a disguised name (.cache or dotnet_diag_.exe), chmodded 0o755, and spawned detached via /bin/sh -c or cmd.exe /c start. Host strings and API names are reconstructed at runtime from array-join fragments (e.g., ["oob-worker.cf103-070.work","ers.d","ev"].join("")) to evade static analysis. A second module lib/telemetry.js ships the same dropper primitives with require("child_" + "process") and fs["chmod"+"Sync"] indirection, bundled as a ready-to-wire payload alongside the active dropper.

Mitigation

Aliases