The folder C:\ProgramData\Symantec\Symantec Endpoint Protection\<Current Version>\Data\CmnClnt\ccSubSDK\ is filling up with thousands of submission files that are all of similar size around 3.85MB.
Some
C:\blp\Wintrv\blpcbbap.exe
This issue is resolved in SEP 14.3 RU1. To upgrade to the latest build of SEP.
Workaround
Disable Client Submissions under External Settings for affected clients.