Are old computers more secure?

The FAA has responded to a Government Accounting Office report that the agency hasn't finished implementing security systems and is vulnerable to attack, by saying that the age of the systems would make it very difficult for hackers to break in.

The FAA contends that hackers wouldn't know where to begin to crack the codes in some of the decades-old hardware that is still in use. The agency says that because the systems are custom-built with proprietary software and special-purpose operating systems, it would take a talented hacker to break in. And while the GAO acknowledges that, it also reminds the FAA that there's nothing to stop a disgruntled employee (and there seems to be no shortage of them) from causing havoc.

 Security by obsolescence?