When executing the command SPnnnnn.exe -s (SP82476.exe -s) in order to install the security update the files are first silent extracted to the folder c:\swsetup\SPnnnnn and then the actual installation is started automatically and a new CMD windows pops up so that no silent installation is possible. There is no switch that can be used with provided SPnnnnn.exe file to run the installation of the security update silent.
SOLUTION:
Extract the SPnnnnn.exe files and save them in SPnnnnn folder respectivly and start the installation of the update by executing:
.\SPnnnnn\CallInst.exe /app Update.bat /hide (e.g. .\sp82476\CallInst.exe /app Update.bat /hide)