tcb-web-images@20.5.3

Analysis

tcb-web-images@20.5.3 is a multi-stage binary dropper disguised as a lightweight image wrapper. On require(), the package fingerprints the host (platform, architecture, hostname, memory, CPU count), then downloads a platform-specific binary payload from Cloudflare Workers C2 endpoints via HTTPS GET to paths /pkg/package (linux x64), /pkg/package-arm64 (linux arm64), /pkg/loader_mac (macOS), or /pkg/package.exe (Windows). The C2 hosts are oob-worker[.]cf99-9b3[.]workers[.]dev, oob-worker[.]cf100-416[.]workers[.]dev, oob-worker[.]cf101-adf[.]workers[.]dev, and oob-worker[.]cf103-070[.]workers[.]dev. If HTTPS download fails, it falls back to DNS TXT-based chunked retrieval from domains tin[.]dl[.]well1[.]site, tina[.]dl[.]well1[.]site, ldr[.]dl[.]well1[.]site, and win[.]dl[.]well1[.]site. The downloaded binary is written to /var/tmp/.cache_<random> (Linux/macOS) or %TEMP%\dotnet_diag_<random>.exe (Windows) and executed as a detached background process. A marker file at /tmp/.analytics_state (or %TEMP%\analytics_state on Windows) prevents re-download within approximately 6 hours. The package has no repository, no README, and its index.js exports a stub class that does nothing — the sole purpose is to load the dropper.