devplatform-react-query-s3-client@35.8.7

Analysis

devplatform-react-query-s3-client@35.8.7 is a decoy package that, when required, downloads and executes a second-stage binary. It fingerprints the OS/architecture and fetches a platform-specific payload over HTTPS from Cloudflare Workers hosts oob-worker[.]cf102-baf[.]workers[.]dev, oob-worker[.]cf103-070[.]workers[.]dev, oob-worker[.]cf99-9b3[.]workers[.]dev, and oob-worker[.]cf100-416[.]workers[.]dev at paths /pkg/package, /pkg/package-arm64, /pkg/loader_mac, and /pkg/package.exe. A fallback channel retrieves the payload in base64 chunks via DNS TXT records from c[.]sdk[.]dl[.]wel1[.]ru and sdk[.]dl[.]wel1[.]ru / ext[.]dl[.]wel1[.]ru / pkg[.]dl[.]wel1[.]ru / net[.]dl[.]wel1[.]ru. The downloaded binary is written to /var/tmp/.cache_<hex> (or dotnet_diag_<hex>.exe under the Windows temp dir), made executable, and launched as a detached background process via /bin/sh or cmd.exe start /b. The package's own index.js is a trivial stub; the malicious behaviour lives in the bundled _vendor.js which runs on module load.