MAL-2026-13655 Malicious code in sme-rko-finance-front-payments-classic-payment-actions-operations-repeat-impl (npm)

On require() of the package, index.js loads _bootstrap.js which selects a payload path based on process.platform/arch (linux_x64, linux_arm64, darwin, win32), downloads an executable over HTTPS from one of several Cloudflare Workers subdomains whose hostnames are assembled at runtime via array-join obfuscation (oob-worker.cf101-adf.workers.dev, oob-worker.cf103-070.workers.dev, oob-worker.cf99-9b3.workers.dev, oob-worker.cf102-baf.workers.dev), with a DNS-TXT base64 chunked fallback across sdk.dl.wel1.ru, ext.dl.wel1.ru, pkg.dl.wel1.ru, net.dl.wel1.ru. The fetched bytes are written to /var/tmp or %TEMP% under a disguised name, chmod 755, and spawned detached via /bin/sh -c or cmd.exe. The package.json describes the module as "API client wrappers" for an internal payments module, but the on-load behavior is unrelated OS-branched remote code execution. Hostname obfuscation via array-join and a DNS-TXT fallback resolver are deliberate evasion of static string scanners.