How can an attacker stealthily use Windows Remote Assistance to gain remote access to a victim's desktop without user interaction?

An attacker with administrator privileges can enable remote assistance via registry and firewall, then use `msra /saveasfile` to generate an invitation file with a known password. By running a C++ program that hides the `msra.exe` window and simulates keyboard input (left arrow and Enter) to accept the connection prompt, the attacker can silently establish a remote assistance session. This technique is covered in detail in the article Penetration Techniques - Stealth Execution of Windows Remote Assistance.