Tags: rev
Rating:
# Challenge Name: snek
## Detailed solution
Starting by checking the challenge file
```
file snek
snek: python 3.7 byte-compiled
```
It's a pyc file, a compiled bytecode of Python code
We need to decompile it to get the source code. i'll use the Python byte-code decompiler **uncompyle6**
https://pypi.org/project/uncompyle6/
```
uncompyle6 snek.pyc
# uncompyle6 version 3.7.4
# Python bytecode 3.7 (3394)
# Decompiled from: Python 3.6.8 (tags/v3.6.8:3c6b436a57, Dec 24 2018, 00:16:47) [MSC v.1916 64 bit (AMD64)]
# Embedded file name: snek.py
# Compiled at: 2021-04-08 07:24:05
# Size of source mod 2**32: 834 bytes
"""
Written for RITSEC CTF 2021
Author: knif3
Flag: RITSEC{}
TODO: Finish this challenge
"""
class d(object):
def __init__(self, password):
self.password = password.encode()
self.decrypt = [97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 95, 82, 83, 123, 97, 108, 108, 95, 104, 105, 36, 36, 95, 97, 110, 100, 95, 110, 48, 95, 98, 105, 116, 51, 125]
def __eq__(self, other):
if self.password == bytes(self.decrypt):
print('!flag')
return True
return False
x = input('Enter my name: ')
a = d(x)
if a == x:
print('IS_THIS_THE_FLAG??')
print('NOPE')
else:
print('WRONG')
# okay decompiling snek.pyc
```
We can see that the input is compared to a decrypted flag
We can make a simple Python script to decrypt it
```python
decrypt = [97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 65, 66, 6>
flag = bytes(decrypt).decode()
# print(flag) -> abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_RS{all_hi$$_and_n0_bit3}
print(flag[53:])
```
## Flag
```
RS{all_hi$$_and_n0_bit3}
```
