RE: XSS vulnerability

["Anthony Cicalla" <Anthony.Cicalla () hackersafe com>]

I would start with www.owasp.org which is open web application security
project. Download Webgoat and get started. Also look at ha.ckers.org
they have an xss cheat sheet. XSS or cross site scripting has to deal
with inserting some scripting language into a parameter that has not
been passed through proper input validation before the data is used.
There are two ways that I presently know how to deal with this. Fix your
code if you don't validate input from the client or get an application
level firewall to prevent the attacks. 

Anthony

-----Original Message-----
From: listbounce () securityfocus com [mailto:listbounce () securityfocus com]
On Behalf Of Heng Kuo Kuang Kelvin NCS
Sent: Thursday, December 13, 2007 6:55 PM
To: security-basics () securityfocus com
Subject: XSS vulnerability

Hi,
I tried to google for XSS vulnerability, how to hack, how to prevent,
etc. However, I have no any meaningful information for me to work with.

Actually, I am supposed to address some XSS vulnerability on some of the
in-house application developed by 3rd party vendor. My web server is
already patched to its latest version, however the coding in the
application is subjected to XSS vulnerability, I would like to do
something about it rather than waiting for the application developer to
rewrite the application.

Can anyone of you help me by giving me some guidance?

1) What kind of pattern will I be able to pick up from my web server
logs to show that there is XSS attacks against my web server?
2) How can I prevent XSS from attacking my web servers [Apache, Sun One,
IIS 5 & 6] without having to change the application coding? 
3) How can I test for XSS vulnerability on my web servers?

Any information will be greatly appreciated. 

Thanks in advance

Regards,
Kelvin Heng