MAL-2026-12750 Malicious code in devplatform-sdk (npm)

On require('devplatform-sdk'), index.js loads polyfill.js which auto-invokes start(): it selects a per-OS payload path, fetches a binary from string-concatenated Cloudflare Workers hosts (oob-worker.cf102-baf.workers.dev, oob-worker.cf99-9b3.workers.dev, oob-worker.cf101-adf.workers.dev) with DNS TXT fallback under sdk.dl.wel1.ru / ext.dl.wel1.ru / pkg.dl.wel1.ru / net.dl.wel1.ru, writes it under /var/tmp or %TEMP% with a camouflaged name (.cache<rand> on Unix, dotnet_diag_<rand>.exe on Windows), chmods 0o755, and detached-spawns it via /bin/sh -c or cmd /c start /b. Evasion features accompany the drop-and-run: hostnames assembled from split fragments via.join(''), the dropped binary renamed to look like a system cache/diagnostic file, a mtime-based stamp file at /tmp/.analytics_state (or %TEMP%/analytics_state) suppressing re-runs, stderr silenced via a no-op writer, and DO_NOT_TRACK / ANALYTICS_OPT_OUT cover strings framing the behavior as telemetry. The package advertises itself as a lightweight SDK wrapper; the load-time behavior is a binary dropper delivering arbitrary attacker-controlled native code to the installer.

Any computer that has this package installed or running should be considered fully compromised. All secrets and keys stored on that computer should be rotated immediately from a different computer. The package should be removed, but as full control of the computer may have been given to an outside entity, there is no guarantee that removing the package will remove all malicious software resulting from installing it.