SSAS session cubes are usually generated by grouping activity in Excel pivot tables. Or by directly executing the “create session cube …” command.
Starting with a security patch (KB 3080856) in SQL Server 2012 SP2 CU8 we introduced the SessionCubesMode property with three values.
We have the following values:
0 Disable session cubes
1 Default , presence of some types of security (f.i. non-trivial cell security) will fail session cubes
2 Backward compatibility , restores pre- SSAS 2012 SP2 CU8 behavior
The value of “0” will allow you to disable all session cube activity. Excel clients trying to do grouping will receive an error. See also this communication: https://blog.crossjoin.co.uk/2016/02/08/disabling-excel-pivottable-grouping-and-session-cubes-in-ssas-multidimensional/
The default value is “1” which will activate the security fix for a “dynamic security” issue described in KB 3080856. As a side effect you may see error messages for session cube creation if certain types of security are present in your cube model. Most notably non-trivial cell security in your role will trigger this error:
"Cell Security is disabled for session cubes and member grouping scenarios."
The value of “2” will restore the pre-SSAS 2012 SP2 CU8 behavior. Which means the “dynamic security" issue described in KB 3080856 will still be present. This is fine if you do not use dynamic security in your SSAS roles. However, if you do use use “dynamic security” then please check if the KB 3080856 scenario can affect you. If it does, then you should use SessionCubesMode=1 or 0.