GEN:SID 1:2305
Message WEB-PHP chatbox.php access
Summary This event is generated when an attempt is made to access the script
chatbox.php on a web server running a PHP application.
Impact Denial of Service (DoS).
Detailed Information This event is generated when an attempt is made to access the script
chatbox.php on a web server. This application does not perform stringent
checks when validating data supplied by the user in the Name field of
the script. HTML or script code supplied via that field may cause a
Denial of Service condition to occur.
Affected Systems All systems running E107 versions 0.545 and 0.603, other versions may
    also be affected
Attack Scenarios The attacker could supply some offending HTML code into the name field
and cause the DoS.
Ease of Attack Simple.

Proof of concept exists, in the name field enter:

<script type=javascript>alert('foo')</script>
Corrective Action Ensure the system is using an up to date version of the software and has
had all vendor supplied patches applied.
Additional References  
Rule References bugtraq: 8930