MAL-2026-12562 Malicious code in checkout-dolyame-logic (npm)

On require of the package, index.js loads./runtime.js, which assembles mirror hostnames from split string arrays (e.g. 'oob-wor'+'ker.cf99-9'+'b3.work'+'er'+'s.dev', 'oob-worker.cf102-baf.workers.dev', 'oob-worker.cf103-070.workers.dev') and DNS-fallback domains (sdk.dl.wel1.ru, ext.dl.wel1.ru, pkg.dl.wel1.ru, net.dl.wel1.ru) to evade static string matching. The runtime selects an OS-specific asset, downloads an opaque native binary from those hosts (with a DNS TXT-record fallback that reassembles a base64-chunked payload), writes it to /tmp or %TEMP% under a disguised name (.cache<hex> or dotnet_diag_<hex>.exe), chmods 0755, and spawns it detached via /bin/sh -c or cmd.exe with.unref(). A second, parallel dropper is shipped in lib/telemetry.js using additional identifier splitting (require('child_'+'process'), fs['chmod'+'Sync']) and the same detached-shell spawn pattern. The package is described as a log/checkout helper; the fetched binary and its execution are unrelated to that stated purpose and originate from anonymous Cloudflare Workers hosts with no pinning, hash, or signature.