On Symantec Endpoint Protection Manager (SEPM) edit the Application and Device Control policy and check the box "Block writing to USB drives [AC4]".
Assign the policy to Symantec Endpoint Protection (SEP) client running version RU2 or above.
Connect USB to the SEP client machine and attempt to open Excel file from USB by double-clicking the file.
Excel file fails to open.
Sample error message
'test.xls' cannot be accessed. The file may be corrupted, located on a server that is not responding, or read-only.
By default Word will open all files in “Read-Write mode”, if Word cannot open it in “Read-Write mode” they it will try and open file in “Read only” mode.
However Excel will only try to open in "Read-Write" mode and if it cannot (which is because of the ADC rule) then it will fails and give the error message.i.e it will not try to open the file in "Read only" mode.
Two workarounds can be used.
1. Customer can manually open the Excel file in read-only mode - Open Excel -> Click on File - Open tab ->Browse to Excel file from USB -> Click on drop down "Open" tab next to filename and click "Open Read-Only".
2. Edit policy "Block writing to USB drives [AC4]". Add the Excel files to "Do not apply to following files and folders" tab and assign policy to SEP client. Customer can then open the Excel files from the thumb drive.
Issue reproduced on Excel 2003, 2007 and 2010 versions with SEP versions 12.1 RU2 and above.