Surprised nobody else shared the more simple solution to get flag3. So i am posting it.

```
cd /home
ls
lucifear spookyboi
su - spookyboi
password:
```

The password was revealed in the challenge *past demons* : **zxcvbnm**

From here on use ```find /home -name flag3.txt``` and then ```cat /path_to_file/flag3.txt```