Date: Mon, 5 Apr 1999 23:50:56 +0200
From: Jan Vogelgesang <wj.Vogelgesang@SAARBRUECKEN.NETSURF.DE>
To: BUGTRAQ@netspace.org
Subject: security hole in ICQ-Webserver

Hi,
Some days ago i've read a message here in Bugtraq from Ronald A. Jarell 
about a vulnerability in the ICQ-Webserver . I tried to reproduce this 
vulnerability with my computer (win95) and find out the following:
-sending any non-http stuff or even a simple "get" (without any other 
characters however) crashes the ICQ-Client. This works with ICQ99a V2.13 
Build 1700, but not with Build 1547.

Moreover, there is a much bigger hole in the ICQ-Webserver: If you have 
the webserver enabled, everyone can access your complete(!) harddisk 
with a simple webbrowser.  When your page is activated and you are online, 
each request to "http://members.icq.com/<your ICQ-Number>" will be 
redirected to your computer. Thus, every visitor get to know your current ip.
Nevertheless, only the files in "/ICQ99/Hompage/<your ICQ-Number>/personal" 
should be accessible. But a visitor can "climb up" the directory tree with 
some dots, e.g. "http://<yourIP>/...../a2.html" would present him the file 
"a2.html" in the "ICQ99" directory. With some more dots, he would come to 
the root-directory of your harddisk.  But there is one barrier: The 
ICQ-Webserver only delivers files with a ".html" extension. After some 
experiments I found a way to trick it out: I add ".html/" to the URL and 
the Webserver sends every file I request. For instance,
"http://<yourIP>/............./config.sys" won't work, but 
"http://<yourIP>/.html/............./config.sys" would.
I have test this both with Build 1700 and with Build 1547.

In my opinion, this is a significant security problem, because password 
files or even the registry in the windows directory can be read.
I warned Mirabilis about it and hope they will informe the ICQ-community.
sorry for my poor english...

Jan Vogelgesang

