On April 14th, 2006, Richard Stiennon wrote an article in ZDNet entitled Why Windows is less secure than Linux. Stiennon starts by saying: "Many millions of words have been written and said on this topic. I have a couple of pictures. The basic argument goes like this. In its long evolution, Windows has grown so complicated that it is harder to secure. Well these images make the point very well".
In his post, Stiennon explains that both images (shown here) represent a map of system calls that occur when a web server serves a single HTML page with a picture. The same page and picture have been used on both servers for the purpose of testing. Richard further explains: "A system call is an opportunity to address memory. A hacker investigates each memory access to see if it is vulnerable to a buffer overflow attack. The developer must do QA on each of these entry points. The more system calls, the greater potential for vulnerability, the more effort needed to create secure applications".
The resulting images were generated by Sana Security. The first image is of the system calls that occur on a Linux server running Apache; while the second is of a Windows Server running IIS. The images speak for themselves.