Levcgi.coms MyGuestbook JavaScript Injection Vulnerability

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Levcgi.coms MyGuestbook JavaScript Injection Vulnerability
Discovered By BrainRawt (brainrawt@xxxxxxxxxxx)

About MyGuestbook:
------------------
Highly customizable guestbook that was released on Feb. 20, 2002, and
can be downloaded at http://www.levcgi.com/programs.cgi?program=myguestbook

According to the website, ...myGuestbook has been downloaded 1298 times!

Vulnerable (tested) Versions:
--------------------
MyGuestbook v 1.0

Vendor Contact:
----------------
4-28-02 - Emailed lev@xxxxxxxxxxxxxxxxxxx

4-30-02 - No Reply from the author and I have decided not to wait since I
          never got a reply about another concern i had several months ago
          involving one of his cgi scripts.

Vulnerability:
----------------
myguestbook inproperly filters input to the guestbook making the guestbook
prone to cross-site scripting attacks by malicious visitors to the site. 
This
could be a medium to high concern when mixed with a website that uses 
cookies.

Exploit (POC):
----------------
Sign up and post using the "name" 
<script>alert('evil+java+script+here')</script>

or

When posting comments just insert the 
<script>alert('evil+java+script+here')</script>
to the comments field.


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