Hi,
Thank you for posting in Symantec community.
It seems you are talking about SEP.cloud formerly known as Symantec Endpoint Protection Small Business Edition 2013.
You can block and allow USB devices as per the policy settings,
USB Device Control enables administrators to prevent malicious code injection and intellectual property theft by controlling employee use of USB removable storage devices. USB mice and keyboards are unaffected by USB Device Control as they are not recognized or classified as storage devices by Windows. This control provides the functionality to either allow or block these devices by policy at the endpoint.
- Allow:When policy allows USB devices, all computers in the groups to which the policy applies have complete access to USB storage devices. Allow is the default setting. Read-only access for USB storage devices can also be configured.
- Block:When policy blocks USB devices, access to USB storage devices is disabled and notifications of these blocks may be enabled on the endpoint. These notifications appear as small pop-up messages in the bottom, right-side corner of the endpoint computer. Notifications are off by defa
Reference: SEP SBE .Cloud: USB Device Control Policy
http://www.symantec.com/docs/TECH217392