vishwaCTF 2021: Peace | szymanski.ninja

Peace

Category: Forensics

460 points

commando1(radio)- ive tapped into enemy frequency and got a shocking news here’s the message…over n out commando2 (radio)- roger …

file: morse.rar

Solution

Attached archive is protected with password. Let’s try to break it ;-)

rar2john morse.rar
rar2john morse.rar > john.hash

morse.rar:$rar5$16$7e3b9f3f0a1483c15c1533ee12c27197$15$d4fcbb4605a5aa28d348f2d83d76840c$8$903a4c737f512e87

john --wordlist=rockyou.txt john.hash

Using default input encoding: UTF-8
Loaded 1 password hash (RAR5 [PBKDF2-SHA256 256/256 AVX2 8x])
Cost 1 (iteration count) is 32768 for all loaded hashes
Will run 8 OpenMP threads
Press 'q' or Ctrl-C to abort, almost any other key for status
0g 0:00:00:03 0,02% (ETA: 00:02:35) 0g/s 1156p/s 1156c/s 1156C/s energy..dodgers
india            (morse.rar)
1g 0:00:00:07 DONE (2021-03-13 20:11) 0.1315g/s 1145p/s 1145c/s 1145C/s allahuakbar..taiwan
Use the "--show" option to display all of the cracked passwords reliably
Session completed.

Ok, india is the password. What’s next?

unar morse.rar

morse.rar: This archive requires a password to unpack.
Password (will not be shown): 
RAR 5
  morse (1).wav  (980604 B)... OK.
Successfully extracted to "./morse (1).wav".

Audio file contains some morse encoded message. I’m a bit lazy, so I’ve used https://morsecode.world/international/decoder/audio-decoder-adaptive.html to decode it.

Got below result, which looks like a hexcode (no shit Sherlock!).

76 69 73 68 77 61 53 =STT 66 7B 37 68 33 79 5F 34 72 45 5F 46 30 72 33 66 65 37 31 6E 67 7D

Let’s decode it.

echo 76 69 73 68 77 61 63 74 66 7B 37 68 33 79 5F 34 72 45 5F 46 30 72 33 66 65 37 31 6E 67 7D | xxd -p -r

vishwactf{7h3y_4rE_F0r3fe71ng}

Flag

vishwactf{7h3y_4rE_F0r3fe71ng}