#!/usr/bin/env python3

import os

class Module:

def __init__(self, incoming=False, verbose=False, options=None):

# extract the file name from __file__. __file__ is proxymodules/name.py

self.name = os.path.splitext(os.path.basename(__file__))[0]

self.description = 'Replace hex data on the fly defining search and replace-pairs in a file or as module parameters'

self.verbose = verbose

self.filename = None

self.separator = ':'

self.len = 16

search = None

if options is not None:

if 'search' in options.keys():

search = bytes.fromhex(options['search'])

if 'replace' in options.keys():

replace = bytes.fromhex(options['replace'])

if 'file' in options.keys():

self.filename = options['file']

try:

open(self.filename)

except IOError as ioe:

print("Error opening %s: %s" % (self.filename, ioe.strerror))

self.filename = None

if 'separator' in options.keys():

self.separator = options['separator']

self.pairs = [] # list of (search, replace) tuples

if search is not None and replace is not None:

self.pairs.append((search, replace))

if self.filename is not None:

for line in open(self.filename).readlines():

try:

search, replace = line.split(self.separator, 1)

self.pairs.append((bytes.fromhex(search.strip()), bytes.fromhex(replace.strip())))

except ValueError:

# line does not contain separator and will be ignored

pass

def hexdump(self, data):

result = []

digits = 2

for i in range(0, len(data), self.len):

s = data[i:i + self.len]

hexa = ' '.join(['%0*X' % (digits, x) for x in s])

text = ''.join([chr(x) if 0x20 <= x < 0x7F else '.' for x in s])

result.append("%04X %-*s %s" % (i, self.len * (digits + 1), hexa, text))

print("\n".join(result))

def execute(self, data):

if self.verbose:

print(f"Incoming packet with size {len(data)}:")

for search, replace in self.pairs:

if search in data:

if self.verbose:

print("########## data found ###########")

print("[Before:]")

self.hexdump(data)

data = data.replace(search, replace)

if self.verbose:

print("[After:]")

self.hexdump(data)

return data

def help(self):

h = '\tsearch: hex string (i.e. "deadbeef") to search for\n'

h += ('\treplace: hex string the search string should be replaced with\n')

h += ('\tfile: file containing search:replace pairs, one per line\n')

h += ('\tseparator: define a custom search:replace separator in the file, e.g. search#replace\n')

h += ('\n\tUse at least file or search and replace (or both).\n')

return h

if __name__ == '__main__':

print('This module is not supposed to be executed alone!')