I admit that this type of Denial of Service is probably the most stupid thing I have found but it works and works very well too!
Today I have released a couple of advisories which contains also references to this bug, so you could be interested in taking a look to them:
http://aluigi.org/adv/unrwebdos-adv.txt
http://aluigi.org/adv/toribashish-adv.txt
I have already searched on internet some days ago and found nothing related to this problem so now I will spend some words about it.
As probably all the people which have played with the Windows console already know, there is an annoying problem which happens when invalid chars are visualized on the screen.
In my tests seems that on Windows 9x the problem isn't too much while on Windows XP (and 2k too probably) it's an hell.
How many time you have been remained with the console freezed and the sound speaker yelling while playing with netcat and services which use non-textual data?
The last time this happened to me was at job and the system slowed so quickly that toke me many seconds to kill that damned process with all my collegues watching me... ah ah ah
Anyway this stupid effect of the invalid and bell chars can be used as attack versus servers which run in console and visualize the user's input.
The only requirements are:
- ability to visualize many chars
- no restrictions on the chars, it's important that at least the bell char 0x07 is visualized
- naturally the Window console
The effects are a great slowness of the entire system, the process which is completely freezed (DoS) and the absurd noisy sound you must hear.
Not an attack which will remain in the history but if you are going to test a server which works in console you should care about this type of problem too since the effects work and it can be used in a real attack scenario.
