Incorrect Privilege Assignment

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

The following example demonstrates the weakness.

seteuid(0);
/* do some stuff */

seteuid(getuid());

Example Two

The following example demonstrates the weakness.

AccessController.doPrivileged(new PrivilegedAction() {

  public Object run() {
    // privileged code goes here, for example:
    System.loadLibrary("awt");
    return null;
    // nothing to return

  }

Example Three

This application sends a special intent with a flag that allows the receiving application to read a data file for backup purposes.

Intent intent = new Intent();
intent.setAction("com.example.BackupUserData");
intent.setData(file_uri);
intent.addFlags(FLAG_GRANT_READ_URI_PERMISSION);
sendBroadcast(intent);

public class CallReceiver extends BroadcastReceiver {
  @Override
  public void onReceive(Context context, Intent intent) {
    Uri userData = intent.getData();
    stealUserData(userData);
  }
}

Any malicious application can register to receive this intent. Because of the FLAG_GRANT_READ_URI_PERMISSION included with the intent, the malicious receiver code can read the user's data.

See Also