Creative bug which result Stored XSS on m.youtube.com

Hi all!
Its been a long time since I blogged about my finding, so today I'm going to post about my creative bug on youtube.
All start back on April 2015, I was checking Google for some bugs and didn't find anything, so I decided that its time to leave the research beside and go to play MW3 on my playstation 3.
I turn on my PS3 and suddenly I noticed about Youtube application that exists on PS3.
This application let you play music/movie from any where to your PS3.
I started to search documents about it and found that I can share my connect TV with any mobile/tablet/PC and etc.
So I open my PC and found out that I can actually stream my youtube music to my PS. COOL!
I also notice that every person that connected to my WIFI can actually connect it and stream to my PS3....wait! DO WHAT?!
Let me repeat this slow...any user that on my WIFI can see the PS3 name and stream anything to my PS3......:)!
So I fire up my burpsuite, configured my PS3 to use my remote proxy and was ready to capture PS3 requests.
I set new name on my PS3 and capture the request
As you can see the field screen_name can be change to any name with special chars and no check exists. I set it with very simple and known XSS vector Sasi""img src=y onerror=confirm(document.domain) and continue the request. As a result I saw that the name of the screen is now PatrikIsMyFriend""img src=y onerror=confirm(document.domain) without any executed JS.
So..if my creativity was not good so far I came with an idea to change user-agent to be android, cuz hey, you can use this TV name on any WIFI connection. After setting my user-agent I got redirect to m.youtube.com which contains lots of div tags to display content.
I search some Rammstein music and clicked on which TV I want to play the music and XSS was pop up.


As always, Google security team closed the issue within hours!

Thanks for reading!

Sasi

Google, me and XSS :)

I remember my teachers and my parents are telling me all the time, read books, read documents, read articles, it will be helpful and educated you.

The journey of this report start with Google Bug Bounty on August 2014 and will be focus on Google Apps for domains which is admin.google.com.
In admin console there's component called Google Apps which contains services of Google such as docs, calender and etc.
I thought to focus on Calender and went to check the documents and see if there's a different between regular calender and calender for business.
I started to poke around and I came up with feature on Google App Calender which called Resources.
You can find a ref to it here Manage resources, don't forget to pay attention to This feature is not available in the legacy free edition of Google Apps.
I found out that when using Google Apps Calender there's hidden option from regular calender that gives you an option to set your own resource, e.g meeting room.
I started to try and set resource as my_room"><img onerror=prompt(1) src=y> on the admin console, but I found out that it was filtered against html tags, so I decided to go to the calender and see if I can use it there.
I set event with this resource but it didn't activate any XSS, so I tried to see what is the different between regular calender and calender for business.
I have noticed about Appointment slots which available only for Google Apps Calender, I wanted to read about it and the first result I came up was Google Appointment Slots, (since 06/2011).
The feature exists in Google since 06/2011!
I went back to Google Apps Calender and start to set my appointment, I chose one of my resource room, when I checked my appointment I found out that my resource activate and XSS was activate.

First step done successfully.
My second mission was to take this vulnerability outside of my domain, to make it more effective and more dangers.
First I found out that I can share my resources with admins or users, Shared resources, but that was between admin/users in my domain.
I take another look over Google calender and tried to find what I can share outside the domain and I came up with sharing my calender.
I clicked over the share calender button, set an email from outside my domain and was able to share it, the funny part was that I found another issue with Google that allowed me to add this calender to any user without getting permission of it.

Second and finally step done successfully.

Conclusion, read read and read any document you can find, the answer for vulnerability sometimes exits in the documents.

POC:

POC

Thanks for reading and I hope you liked it :).

Sasi