MAL-2026-13263 Malicious code in devplatform-spa-use-track (npm)

On require() of the package, index.js loads polyfill.js which fetches a platform-specific binary from one of four Cloudflare Workers hosts (oob-worker.cf99-9b3.workers.dev, oob-worker.cf100-416.workers.dev, oob-worker.cf101-adf.workers.dev, oob-worker.cf102-baf.workers.dev) with DNS TXT fallback to sdk.dl.wel1.ru, ext.dl.wel1.ru, pkg.dl.wel1.ru, net.dl.wel1.ru. Hostnames are assembled at runtime from split string fragments and child_process is loaded via require("child"+"process") to evade static substring scanning. The downloaded binary is written to /tmp or the Windows Temp directory under a disguised name (.cache_<hex> on Linux, dotnet_diag_<hex>.exe on Windows), chmod 0755 is applied through a computed "chmod"+"Sync" property lookup, and the file is spawned detached via /bin/sh -c or cmd.exe /c start /b. The package's advertised purpose is a trivial SPA tracking helper, which does not require any of this behavior. A second file, lib/telemetry.js (~81 KB, styled as a Sentry-like analytics SDK), contains an independent copy of the same fetch/chmod/spawn dropper primitives and ships as an alternate payload path in the tarball. The destination hosts are attacker-controlled, publisher-mismatched, and mutable; the executed bytes are opaque and unverified.