After four years it was discovered that Microsoft programmers had inserted a back door in their popular FrontPage Web server software. Most experts believe that the odds of a such a back door slipping in are nil. Apache has never had an exploit like this, and never will. Nor will Linux, or the BIND library, or Perl, or any of the other open source core software available. In other words, since the source code is open for all to review, numerous programmers worldwide will be examining the code for security vulnerabilities.
Closed source means only the bad guys get to find the security holes.
This promise of peer review promotes secure coding techniques among open source projects, argues Raymond. Warfield, who has worked in both open and closed source development models, says there is a higher standard of personal accountability and greater professionalism among open source programmers. They get fixed. Because of peer review, open source problems can generally be found and fixed before they're widely exploited. Another perk of open source is that the software actually evolves and gets more secure over time.