Incorrect Behavior Order: Early Amplification

Demonstrations

The following examples help to illustrate the nature of this weakness and describe methods or techniques which can be used to mitigate the risk.

Note that the examples here are by no means exhaustive and any given weakness may have many subtle varieties, each of which may require different detection methods or runtime controls.

Example One

This function prints the contents of a specified file requested by a user.

function printFile($username,$filename){


  //read file into string
  $file = file_get_contents($filename);
  if ($file && isOwnerOf($username,$filename)){
    echo $file;
    return true;
  }
  else{
    echo 'You are not authorized to view this file';
  }
  return false;

}

This code first reads a specified file into memory, then prints the file if the user is authorized to see its contents. The read of the file into memory may be resource intensive and is unnecessary if the user is not allowed to see the file anyway.

See Also