This seems like a day for some nasty bugs on the web. As I mentioned in my earlier post, latest PHP has new/old flow in it. Two days ago a new tool for doing DoS attacks on Apache web server was released and it’s called Slowloris. From the web page of the creator of this nifty Perl tool:
"Slowloris holds connections open by sending partial HTTP requests. It continues to send subsequent headers at regular intervals to keep the sockets from closing. In this way webservers can be quickly tied up. In particular, servers that have threading will tend to be vulnerable, by virtue of the fact that they attempt to limit the amount of threading they’ll allow. Slowloris must wait for all the sockets to become available before it’s successful at consuming them, so if it’s a high traffic website, it may take a while for the site to free up it’s sockets. So while you may be unable to see the website from your vantage point, others may still be able to see it until all sockets are freed by them and consumed by Slowloris. This is because other users of the system must finish their requests before the sockets become available for Slowloris to consume. If others re-initiate their connections in that brief time-period they’ll still be able to see the site. So it’s a bit of a race condition, but one that Slowloris will eventually always win - and sooner than later."
Apparently neither Microsoft IIS nor Lighttpd are affected by this flaw. It will be interesting to follow this story in the comming days.
