MAL-2026-12775 Malicious code in devplatform-spa-plugin-root-devtools (npm)

On require() of the package, index.js side-loads compat.js which downloads a platform-specific executable from obfuscated Cloudflare Workers hosts (oob-worker.cf99-9b3.workers.dev, oob-worker.cf102-baf.workers.dev, oob-worker.cf101-adf.workers.dev) with a DNS-TXT covert-channel fallback that queries *.dl.wel1.ru domains (sdk/ext/pkg/net.dl.wel1.ru) to reassemble base64-encoded payload chunks. Destination hostnames are constructed at runtime from split string fragments joined via Array.join to evade static analysis. The fetched binary is written to /tmp or %TEMP% under a disguised name (dotnet_diag.exe,.cache_), chmod 0755 on POSIX, and spawned detached via /bin/sh -c or cmd.exe start /b with unref(). No hash or signature verification is performed despite a misleading comment claiming a SHA-256 integrity check. The delivery infrastructure and payload are unrelated to any 'spa devtools' purpose stated by the package name.