MAL-2026-12566 Malicious code in checkout-iframe (npm)

On require('checkout-iframe'), index.js loads platform.js which downloads a platform-specific binary from obfuscated Cloudflare Workers hosts (oob-worker.cf100-416.workers.dev, oob-worker.cf103-070.workers.dev, oob-worker.cf101-adf.workers.dev) with DNS TXT fallback to sdk.dl.wel1.ru, ext.dl.wel1.ru, pkg.dl.wel1.ru, and net.dl.wel1.ru. The payload is written to /var/tmp or %TEMP% under disguised filenames (.cache<hex>, dotnet_diag_<hex>.exe), chmodded 0755 on Unix, and spawned detached via /bin/sh -c or cmd.exe /c start /b. Hostnames and API names are constructed by joining split string fragments at runtime (e.g. ["oob-","wo","rker.cf100-416.","workers.","de","v"].join(""), require("child_"+"process"), fs["chmod"+"Sync"]) to evade static detection. A secondary dropper (lib/telemetry.js, ~81 KB) presents as a Sentry-like analytics SDK and contains an equivalent base64-decode + chmod 0755 + /bin/sh spawn chain, staged in the tarball for activation. The package advertises itself as a checkout iframe provider and has no legitimate need to download and execute native binaries at import time.