For this challenge we have a Google Forms link. After the first page, we get to a page that redirects to itself when answered.
![teste](https://i.imgur.com/frVIFBd.png)
We are getting nowhere like this, so we can check the page source code, Most of it is irrelevant, but one hidden input is very interesting:
 `<input type="hidden" name="pageHistory" value="0,1,1,1">`
Seems like Google Forms stores the user's page history in a hidden input element. Our goal is to get out of the infinite loop, so I will modify this history like this:
`<input type="hidden" name="pageHistory" value="0,1,2,1">`
If I press back on the form, it should redirect me to page 2 of the form. And as such half of the flag is revealed. Clicking Submit reveals the rest of the flag
![](https://i.imgur.com/qW5vDU9.png)
![](https://i.imgur.com/uHK7JRd.png)
Flag:  **lactf{l34k1ng_4h3_f04mz_s3cr3tz}**
