J2EE Bad Practices: Use of System.exit()

Description

It is never a good idea for a web application to attempt to shut down the application container. Access to a function that can shut down the application is an avenue for Denial of Service (DoS) attacks.

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

Included in the doPost() method defined below is a call to System.exit() in the event of a specific exception.

Public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  try {
    ...
  } catch (ApplicationSpecificException ase) {
    logger.error("Caught: " + ase.toString());
    System.exit(1);
  }
}

See Also