MAL-2026-12165 Malicious code in bigops-external-auth (npm)

On require('bigops-external-auth'), index.js loads adapter.js which downloads a platform-specific native binary from Cloudflare Worker hosts whose hostnames are reassembled at runtime from split string arrays (e.g. ["oob","-wo","rker.cf100-416.worke","rs.de","v"].join("")) to evade static analysis. The fetched bytes are written to a temp path under a disguised name (dotnet_diag.exe /.cache_), chmod 0755, and spawned detached via cp.spawn("/bin/sh", ["-c", fp + " &"], {detached:true}) or spawn("cmd",…) on Windows. If the HTTPS fetch fails, a fallback channel retrieves a base64-chunked payload via DNS TXT records at *.wel1.ru (hostnames also reassembled via.join("")) and reconstructs it with Buffer.from(parts.join(""), "base64"), designed to bypass egress HTTP filtering. A second parallel dropper is shipped in lib/telemetry.js (81KB), masquerading as a Sentry-like SDK, structurally identical to the active dropper (spawn /bin/sh with fetched file, chmodSync 755 via string-concatenated method name fs["chmod"+"Sync"], base64 chunk assembly), not currently on the reachable graph from index.js but present in the tarball. Behavior fires automatically on require/import — any consumer that installs and loads this package executes attacker-controlled native code on the host.