You can also read this and other writeup on my [Github](https://github.com/quochuyy10217/MyCTFWriteups/tree/main/Digital%20Overdose%202021%20Autumn%20CTF)
![Img1](https://user-images.githubusercontent.com/67006728/136659402-0623a624-e2b1-4ae1-98f7-393b9479e2cc.PNG)
This is what you will see when you open the page
![Img2](https://user-images.githubusercontent.com/67006728/136659409-d4e31605-f3e5-452f-82df-f5c1400f111f.PNG)
When I read what they write in the page, I didn't understand at first. But fortunately, I remember what they write in the title of this chall: "git". So i began to check if this page has /.git page or not. And when i did that, something appeared.
![Img3](https://user-images.githubusercontent.com/67006728/136659412-8fd418f6-a520-4fdf-b631-de37646e1e0a.PNG)
But they told me that I don't have permission to see this. But there are many tools can let me gain the permission to the "./git" page. And the one I chose is GitHacker. With this tool, you can download everything in the "./git" page.
![Img4](https://user-images.githubusercontent.com/67006728/136659417-a84c2df2-7809-47b5-bb20-ea766a40cbee.PNG)
After I had downloaded the source code, i remembered what they said "If only you could read the source code". So I went to look for the content of the index.html page.
![Img5](https://user-images.githubusercontent.com/67006728/136659421-e9558cb2-3d7b-4082-a9f8-af6680c7b5d9.PNG)
You can see that, they encrypt the flag got from the "flag.txt" file, but we don't have that file. So i think that we will change something from the index.html page. I used the privatekey and the ciphertext which I got when open the index page, and run the file again to get the flag.
![Img6](https://user-images.githubusercontent.com/67006728/136659427-ab4cfb28-e116-4598-8376-6c2e6a0d2dc8.PNG)
And bingo! The flag is appear :D
![Img7](https://user-images.githubusercontent.com/67006728/136659430-ab86d816-19a7-41a0-8226-86a481503e5b.PNG)
Because the flag will change every time I request a new instance, so I can't show you the flag, but I can show you the way :)))