This Video Shows the Lab Solution of a vulnerable image upload function. Certain file extensions are blacklisted, but this defense can be bypassed using a classic obfuscation technique.
To solve the lab, upload a basic PHP web shell, then use it to exfiltrate the contents of the file /home/carlos/secret. Submit this secret using the button provided in the lab banner.
You can log in to your own account using the following credentials: wiener:peter