You have an account on the application that you can use to help design your attack. The credentials are: carlos / montoya.
The victim will be using Chrome so test your exploit on that browser.
Use the following HTML template and provide the details as follows:
src="$url?name=<img src=1 onerror=alert(1)>&firstname.lastname@example.org&subject=test&message=test#feedbackResult"></iframe>
Go to the exploit server, paste your exploit HTML into the "Body text" box, and click "Store".
Click "View stored response".
Hover over "Test me" and ensure the cursor changes to a hand indicating that the div element is positioned correctly. If not, adjust the position of the div element by modifying the top and left properties of the style sheet.
Click "Test me" and you should see an alert.
Change "Test me" to "Click me" and click "Store" on the exploit server.
The simulated victim now clicks on the div element and the lab should be solved.
If you reload the account page then you will observe that you have successfully completed the lab.