According to the recent article on Fast Company entitled "Apache Killer Is The Biggest Little Internet Threat" by Kit Easto, there is a vulnerability in the latest version (as of 8/28/2011) of Apache Server which is susceptible for DoS attack.
According to Kit Easto, The vulnerability goes like this:
"When your browser asks for website code from an Apache server, the system listens to the request, then sends the relevant HTML files off to you. But your computer can also, of course, download other files from a web server--and as part of the complicated digital chat that goes on between your PC and the Apache server there's a variable named "range" that gets sent from your PC to the server. It basically says "if the file I'm asking for is really big, say a gigabyte, then please break it up into smaller chunks." Apache Killer is a simple code that pings a server, and basically says to the server to break up even a small file into a vast number of tiny chunks, using this "range" variable. The server tries to comply with the request, but it's technically impossible...and so it runs out of memory swiftly, or encounters any number of other errors, and then will typically crash. Taking the server offline, along with any websites it's hosting."
For a potential mitigation, please visit
http://blog.spiderlabs.com/2011/08/mitigation-of-apache-range-header-dos-attack.html
http://blog.spiderlabs.com/2011/08/mitigation-of-apache-range-header-dos-attack.html
