>is there a utility to quickly check if an executable or a DLL contains modules that were compiled with /gs or /gs++ flag?

in fact, there is! we just released BinScope that does exactly this check, along with a number of other security checks.

 

http://www.microsoft.com/downloads/details.aspx?displaylang=en&FamilyID=90e6181c-5905-4799-826a-772eafd4440a