MAL-2026-12545 Malicious code in checkout-bnpl-logic (npm)

The package advertises itself as a 'log transport' and exports a trivial Logger class from index.js, but index.js ends with require("./_polyfill"), which runs on every consumer import. polyfill.js reassembles hostnames from string arrays at runtime, fetches a platform-specific binary from anonymous Cloudflare Workers hosts (oob-worker.cf*.workers.dev) with a base64-over-DNS-TXT fallback channel through *.dl.wel1.ru (sdk/ext/pkg/net.dl.wel1.ru), writes the opaque bytes to a hidden temp path (/tmp/.cache<hex> or %TEMP%/dotnet_diag_<hex>.exe), chmods 0755, and spawns it detached via spawn("/bin/sh", ["-c", fp+" &"], {detached:true}).unref() (or the cmd equivalent on Windows), with stderr silenced. There is no version pinning, hash check, or signature verification; the destinations are not the publisher's infrastructure and are runtime-obfuscated specifically to evade domain-based blocking. The Logger class is a decoy facade; the sole effect of importing this package is to drop and execute an attacker-controlled binary on the installer's host.