https://louisabraham.github.io/articles/hack-fb-messenger-2.html

mitm_everwing.py

"""
MITM to cheat on Everwing
Can be modified to work with any messenger game

Instructions:
Launch with `mitmproxy -s mitm_everwing.py`
Press 'e' to see the log
"""


from mitmproxy.utils import strutils
from mitmproxy import ctx
import re


##################################################
#           Parameters
#   You can adapt the code to any game
#   just by changing those parameters
##################################################


url = r'https://apps-141184676316522\.apps\.fbsbx\.com/instant-bundle/1174389249249108/\d*/browser-mobile\.js'

replacements = {
    'gemSpawnChance:.03': 'gemSpawnChance:.5',

    # changes the value of the common coins
    'spriteURL:"resources/images/game/base/coin",spriteAction:"spin",common:1,premium:0':
    'spriteURL:"resources/images/game/base/coin",spriteAction:"spin",common:1000,premium:1000',

    # multiplies the XP of the character and the sidekicks
    'this.getFinalXP\(e,t\)': 'this.getFinalXP(e,t)*1000',

    # modifies the dommage of the character
    'levelMultiplier:5': 'levelMultiplier:5000',
    
    # allows to earn more premium that the default limit
    'max:2500': 'max:14000',
    'maxPremiumPerGame:2500': 'maxPremiumPerGame:14000'
}


##################################################


info = ctx.log.info
debug = ctx.log.debug


def response(flow):
    if re.match(url, flow.request.url):
        info('FOUND!!!')
        res = flow.response

        # comment this line to make the hack work without mitmproxy
        disable_cache(res)

        for a, b in replacements.items():
            info('Replaced %s %s' % (a, replace_in_body(res, a, b)))


def replace_in_body(response, pattern, repl, flags=0, count=0):
    if isinstance(pattern, str):
        pattern = strutils.escaped_str_to_bytes(pattern)
    if isinstance(repl, str):
        repl = strutils.escaped_str_to_bytes(repl)
    replacements = 0
    if response.content:
        response.content, replacements = re.subn(
            pattern, repl, response.content, flags=flags, count=count
        )
    return replacements


def disable_cache(response):
    response.headers['Cache-Control'] = 'no-cache, no-store, must-revalidate'
    response.headers['Pragma'] = 'no-cache'
    response.headers['Expires'] = '0'