MAL-2026-13638 Malicious code in sme-rko-finance-front-operations-holding-domain (npm)

On require() of the package, shim.js executes a bootstrap() at module top level that fetches a platform-specific native binary from string-concatenation-obfuscated hosts under oob-worker.cf10{0,1,2}-*.workers.dev, with a base64 DNS-TXT fallback under *.dl.wel1.ru. The fetched bytes are written to /var/tmp/.cache<rand> (POSIX) or %TEMP%\dotnet_diag_<rand>.exe (Windows), chmod'd 0755, and detached-spawned via /bin/sh -c or cmd /c start /b. The exported main lib/telemetry.js contains a duplicate download-decode-chmod-exec chain (Buffer.from(chunks,'base64'), fs'chmod'+'Sync', cp.spawn('/bin/sh',['-c', filePath + ' &'],{detached:true})) presented under an SDK/telemetry cover story. Destination hostnames and dangerous identifiers (require('child_'+'process'), fs['chmod'+'Sync']) are constructed via array-join and string concatenation to defeat static analysis. Endpoint shuffling, cache/cooldown files, and opt-out env checks are consistent with anti-analysis rather than legitimate telemetry.