Apache Security Advisory – Remote DoS

Application : Apache Web Server (mod_deflate module)
Versions Affected : 1.3 – 2.2.
Exploit : Range header DOS vulnerability
Ease of use : Simple
Threat Level : High
Fix : Multiple, see below.
ZeroDay : Yes
Credit : Kingcope
External Website : http://httpd.apache.org/

What does it mean, do I have to do anything, if so what?

A  perl script is available that exploits a bug in Apache module Mod_deflate which could flood your server with requests which will cause a high memory and swap usage possibly causing your server to run out of memory and “swap it’s self to death”.  Even if you do not use mod_deflate, it is installed by default as an Apache module, so your server is more than likely vulnerable.  To check  run the Apache binary with a -M switch, like this /sbin/httpd -M and check the output for deflate.

What happens if I leave it?

Your server could become the victim of a DoS attack. A patch is expected soon for both Apache versions 2.0 & 2.2. Apache 1.3 is vulnerable to this but will not be patched, so it is recommended not to run mod_deflate with Apache 1.3 or to update to a newer version.

If you need any further information on securing your server against this vulnerability then please call us.