[Andreas]

If there is none:

In statistik.php FIND

PHP Code:

require_once('/global.php'); 


Right after that ADD

PHP Code:

if (!($permissions['adminpermissions'] & CANCONTROLPANEL)) {
  print_no_permission();
} 


@PCFreak
You might consider using single quotes for strings that don't contain variables, saves processing time as PHP doesn't have to check for variables then.
Using german variable names is somewhat ridicolous and makes it difficult to read the code, although I am a german native speaker