PicoCTF2018 - Miscellaneous - grep2

PicoCTF2018 - Miscellaneous - grep2

Objective:
This one is a little bit harder. Can you find the flag in /problems/grep-2_0_783d3e2c8ea2ebd3799ca6a5d28fc742/files on the shell server? Remember, grep is your friend.


Solution:

@pico-2018-shell:~$ cd /problems/grep-2_0_783d3e2c8ea2ebd3799ca6a5d28fc742

@pico-2018-shell:/problems/grep-2_0_783d3e2c8ea2ebd3799ca6a5d28fc742$ ls -l                                 
total 4
drwxr-xr-x 12 root root 4096 Mar 25 19:18 files

cool so there is a folder name files lets see what's inside

cd files
@pico-2018-shell:/problems/grep-2_0_783d3e2c8ea2ebd3799ca6a5d28fc742/files$ ls -l
total 40
drwxr-xr-x 2 root root 4096 Mar 25 19:18 files0
drwxr-xr-x 2 root root 4096 Mar 25 19:18 files1
drwxr-xr-x 2 root root 4096 Mar 25 19:18 files2
drwxr-xr-x 2 root root 4096 Mar 25 19:18 files3
drwxr-xr-x 2 root root 4096 Mar 25 19:18 files4
drwxr-xr-x 2 root root 4096 Mar 25 19:18 files5
drwxr-xr-x 2 root root 4096 Mar 25 19:18 files6
drwxr-xr-x 2 root root 4096 Mar 25 19:18 files7
drwxr-xr-x 2 root root 4096 Mar 25 19:18 files8
drwxr-xr-x 2 root root 4096 Mar 25 19:18 files9

ok more folders let's check one out

@pico-2018-shell:/problems/grep-2_0_783d3e2c8ea2ebd3799ca6a5d28fc742/files$ cd files0
@pico-2018-shell:/problems/grep-2_0_783d3e2c8ea2ebd3799ca6a5d28fc742/files/files0$ ls
file0  file10  file12  file14  file16  file18  file2   file21  file23  file25  file27  file29  file4  file6  file8
file1  file11  file13  file15  file17  file19  file20  file22  file24  file26  file28  file3   file5  file7  file9

ok so it has a bunch of files in it

Our goal is to find the flag inside one of these files inside one of these folders


Let's use Grep to find out which file contains the string 'pico'

@pico-2018-shell:/problems/grep-2_0_783d3e2c8ea2ebd3799ca6a5d28fc742/files$ grep -rl 'pico'
files5/file23

okay it looks like file23 in the files5 folder has that string lets cat and grep and for the flag

@pico-2018-shell:/problems/grep-2_0_783d3e2c8ea2ebd3799ca6a5d28fc742/files$ cat ./files5/file23 | grep 'pico'
picoCTF{grep_r_and_you_will_find_24c911ab}