MAL-2026-13007 Malicious code in bnpl-blocks-mobile-bnpl-tab-buttons (npm)

On require() of the package, index.js side-loads adapter.js which selects a platform-specific asset, downloads bytes over HTTPS from hostnames reconstructed at runtime by joining split string fragments (oob-worker.cf10{0..3}-*.workers.dev), writes the bytes to a disguised temp file (/tmp/.cache<hex> on POSIX, %TEMP%/dotnet_diag_<hex>.exe on Windows), sets mode 0o755, and spawns the file detached via /bin/sh -c or cmd.exe /c start. A DNS-TXT fallback channel queries c.<domain> then N.<domain> records under *.dl.wel1.ru, base64-decodes the concatenated chunks, and executes the resulting binary when the HTTPS mirrors fail. The package advertises itself as a native bridge with a trivial no-op class in index.js; the dropper logic is hidden in _adapter.js with cover-story variable names (analytics_state, telemetry). Hostname reconstruction from split literals is a deliberate static-scanner evasion technique, and DNS-TXT payload staging is a covert-channel technique to bypass HTTPS egress filtering.