D-Link DCS-825L firmware version 1.08.01 and possibly prior versions contain an insecure implementation in the mydlink-watch-dog.sh script. The script monitors and respawns the dcp and signalc binaries without validating their integrity, origin, or permissions. An attacker with filesystem access (e.g., via UART or firmware modification) may replace these binaries to achieve persistent arbitrary code execution with root privileges. The issue stems from improper handling of executable trust and absence of integrity checks in the watchdog logic.
The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor.