How do you block USB flash drives while allowing other USB devices?
When blocking USB devices in the application and device control policy, it also blocks other devices that are dependent on (commonly floppy drives and hard drives).
When adding any device in the "Blocked Devices" column, it by default blocks other devices that are dependent on that device.
In the Symantec Endpoint Protection Manager, open Policies, then click Application and Device Control.
Warning: Failure to add device exclusions for critical system devices may lead to system instability or blue screens. Some disk controllers may be addressed using a USB bus and will be blocked, possibly blocking SAN and iSCSI devices. Please test all policies before use in a production environment.