The VNC module tests accounts against the VNC service.
This module was developed using both RealVNC and UltraVNC, which support
rudimentary anti-brute force functionality. RealVNC, for example, allows 5
failed attempts and then enforces a 10 second delay. For each subsequent
attempt that delay is doubled. UltraVNC appears to allow 6 invalid attempts
and then forces a 10 second delay between each following attempt. This module
attempts to identify these situations and react appropriately by invoking
sleep(). The user can set a sleep limit when brute forcing RealVNC using the
MAXSLEEP parameter. Once this value has been reached, the module will exit.
Medusa Documentation