Tags: osint 

Rating:

This was the OSINT challenge that our team was not able to solve. However, through this challenge, we manged to learn new things that would be useful in future CTFs.

The intended solution is the fact that Youtube crops the banner image based on the device one is using when accessing Youtube.

![img](https://gblobscdn.gitbook.com/assets%2F-MC_WJo7n-9hFwfJ__aw%2F-MCzDnSU47vs3lfEqhWj%2F-MCzEYDPz1dMaXOezQQ9%2Fimage.png?alt=media&token=29e1a9a5-aade-43c4-aef9-7470dba0b785)

We can use this tool to look at banner images with optimized for different devices (Mobile, TV, etc.)

https://mattw.io/youtube-metadata/

![img](https://gblobscdn.gitbook.com/assets%2F-MC_WJo7n-9hFwfJ__aw%2F-MCzDnSU47vs3lfEqhWj%2F-MCzEtuxqm-tcqKaeSy8%2Fimage.png?alt=media&token=f871e89a-1158-4b9a-8908-a175d6577145)

Under "Branding Settings", we are given a few banner links with different optimizations based on the devices used. Looking at the banner optimized for TVs, we will be able to see the full image that contains the flag.

![img](https://gblobscdn.gitbook.com/assets%2F-MC_WJo7n-9hFwfJ__aw%2F-MCzDnSU47vs3lfEqhWj%2F-MCzFCRXChKX17ioFGnQ%2Fimage.png?alt=media&token=0e0f45a2-1656-4ea9-90c7-356149e87496)

While attempting this challenge, I managed to learn a few things. Looking at the Author's notes, he mentioned that it was "real life OSINT". Thus, I tried to see if I can link the Youtube Account with its corresponding Google Account to find out any real life information which was the wrong approach.

Looking at the page source of the Youtube channel, one is able to find the Google Account ID as shown below.

![img](https://gblobscdn.gitbook.com/assets%2F-MC_WJo7n-9hFwfJ__aw%2F-MCzDnSU47vs3lfEqhWj%2F-MCzFgTdvcYbrmIDJH-b%2Fimage.png?alt=media&token=6f2cc463-5d5c-4c97-8d3a-3ea2fec9d567)

In this case, the Google ID is 100881987903947537523.

So, what can we do with this Google ID? Firstly, we can look at the account's Google Maps and Google Reviews information. We can simply replace the {userID} parameter with the Google ID that we had found earlier.

```
https://www.google.com/maps/contrib/{userID}
```

![img](https://gblobscdn.gitbook.com/assets%2F-MC_WJo7n-9hFwfJ__aw%2F-MCzDnSU47vs3lfEqhWj%2F-MCzGQPwuJCRTqGYYZjb%2Fimage.png?alt=media&token=4099df88-4be9-452c-8089-5f3aad6b0555)

![img](https://gblobscdn.gitbook.com/assets%2F-MC_WJo7n-9hFwfJ__aw%2F-MCzDnSU47vs3lfEqhWj%2F-MCzGTnHbAJgxnoCiRM7%2Fimage.png?alt=media&token=3058c0b1-3944-4ea0-b00a-fd90bb3fc1b8)

We can also view the person's Google Photo Albums (if he/she have any). We can visit the following link, where we replace the {userID} parameter with the Google ID we had found earlier.

```
https://get.google.com/albumarchive/{userID}
```

However, we were not able to find any photo albums linked to the Google Account.

![img](https://gblobscdn.gitbook.com/assets%2F-MC_WJo7n-9hFwfJ__aw%2F-MCzDnSU47vs3lfEqhWj%2F-MCzETzF0cXD4bh2Fi-X%2Fimage.png?alt=media&token=124df104-1a84-4f8b-8191-3be42372cc91)

Despite not being able to solve this challenge during the competition, we managed to learn something new while attempting to solve it, while also learning about the intended solution after the competition from the players and organizers. I feel that this is the beauty of CTFs and the community.

We should not fear attempting difficult challenges as we would always learn new concepts that will help us to solve similar problems in the future :)

Original writeup (https://deric.gitbook.io/ctf-writeups/uiuctf-2020/osint/isabelles-bad-opsec-4).