🛡️ MAL-2026-12662 — constructor-blocks-mailings

Malicious code in constructor-blocks-mailings (npm)

Source: amazon-inspector

On require() of the package, index.js loads _adapter.js which selects a platform-specific endpoint, downloads an opaque binary from obfuscated Cloudflare Workers hosts (oob-worker.cf100-416.workers.dev, oob-worker.cf99-9b3.workers.dev, oob-worker.cf102-baf.workers.dev) with a DNS-TXT base64 fallback channel via numbered subdomains under *.dl.wel1.ru, writes it to /tmp or %TEMP% under disguised names (.cache_<hex>, dotnet_diag_<hex>.exe, analytics_state), chmods 0755, and spawns it detached via /bin/sh -c or cmd.exe /c start. Destination hostnames are assembled from split string fragments (e.g. "oob-worker.c"+"f100-416.workers.dev") to evade static analysis. The fetched bytes are opaque with no hash or signature verification. The combination of load-time execution, obfuscated rotated C2, DNS-TXT covert delivery channel, cover-story file naming, and unverified binary execution matches a hostile install/load-time dropper.