TryHackMe: Ninja Skills Writeup
Ninja Skills is a TryHackMe room for improving Linux command line skills. Note that all answers have been redacted from this writeup.
We are tasked with answering a set of questions about the following files:
- 8V2L
- bny0
- c4ZX
- D8B3
- FHl1
- oiMO
- PFbD
- rmfX
- SRSq
- uqyw
- v2Vb
- X1Uy
The goal is to solve the challenges as efficiently as possible. Most of the challenges can be solved with some form of
find / -name <filename> -exec <command> \;
To keep track of the target files, I added them to a text file:
$ cat filenames
8V2L
bny0
c4ZX
D8B3
FHl1
oiMO
PFbD
rmfX
SRSq
uqyw
v2Vb
X1Uy
Now I can use a for loop to run a command against each file! The basic syntax for this is:
for i in $(cat filenames); do find / -name "$i" -exec <command> \; 2>/dev/null; done
Challenge Questions
Challenge 1: Which of the above files are owned by the best-group group?
Use the -group <groupname> switch to find all files owned by a specific group:
$ find / -group best-group 2>/dev/null
Challenge 2: Which of these files contain an IP address?
We can use grep to find an IP address in a file.
grep -Eo '[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}'
Now, add it to the find command:
$ for i in $(cat filenames); do find / -name "$i" -exec grep -E -o '[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}' '{}' \; 2>/dev/null; done
1.1.1.1
Sweet, it works! To print the filename, change the -o to a -l
$ for i in $(cat filenames); do find / -name "$i" -exec grep -E -l '[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}' '{}' \; 2>/dev/null; done
Challenge 3: Which file has the SHA1 hash of 9d54da7584015647ba052173b84d45e8007eba94
Add -exec sha1sum '{}' \; to our find command in order to take the sha1sum of each file!
$ for i in $(cat filenames); do find / -name "$i" -exec sha1sum '{}' \; 2>/dev/null; done | grep 9d54
Challenge 4: Which file contains 230 lines?
Add -exec wc -l '{}' \; to the find command:
$ for i in $(cat filenames); do find / -name "$i" -exec wc -l '{}' \; 2>/dev/null; done
209 /etc/8V2L
209 /mnt/c4ZX
209 /mnt/D8B3
209 /var/FHl1
209 /opt/oiMO
209 /opt/PFbD
209 /media/rmfX
209 /etc/ssh/SRSq
209 /var/log/uqyw
209 /home/v2Vb
209 /X1Uy
The file that is missing is the answer to the question.
Challenge 5: Which file’s owner has an ID of 502?
View file ownership by adding -exec ls -la '{}' \;.
In the below output, there is one file owner who is not our current user.
$ for i in $(cat filenames); do find / -name "$i" -exec ls -la '{}' \; 2>/dev/null; done
-rwxrwxr-x 1 new-user new-user 13545 Oct 23 2019 /etc/8V2L
-rw-rw-r-- 1 new-user new-user 13545 Oct 23 2019 /mnt/c4ZX
-rw-rw-r-- 1 new-user best-group 13545 Oct 23 2019 /mnt/D8B3
-rw-rw-r-- 1 new-user new-user 13545 Oct 23 2019 /var/FHl1
-rw-rw-r-- 1 new-user new-user 13545 Oct 23 2019 /opt/oiMO
-rw-rw-r-- 1 new-user new-user 13545 Oct 23 2019 /opt/PFbD
-rw-rw-r-- 1 new-user new-user 13545 Oct 23 2019 /media/rmfX
-rw-rw-r-- 1 new-user new-user 13545 Oct 23 2019 /etc/ssh/SRSq
-rw-rw-r-- 1 new-user new-user 13545 Oct 23 2019 /var/log/uqyw
-rw-rw-r-- 1 new-user best-group 13545 Oct 23 2019 /home/v2Vb
-rw-rw-r-- 1 newer-user new-user 13545 Oct 23 2019 /X1Uy
There is one unique file owner. Run id <user> to get their UID.
Challenge 6: Which file is executable by everyone?
The -executable switch displays files that are marked as executable:
$ for i in $(cat filenames); do find / -name "$i" -executable 2>/dev/null; done