mirror of
https://github.com/mgeeky/Penetration-Testing-Tools.git
synced 2024-11-28 13:26:55 +01:00
578 lines
18 KiB
Python
578 lines
18 KiB
Python
#!/usr/bin/python
|
|
|
|
#
|
|
# ReEncoder.py - script allowing for recursive encoding detection, decoding and then re-encoding.
|
|
# To be used for instance in fuzzing purposes. Imagine you want to fuzz XML parameters within
|
|
# **PaReq** packet of 3DSecure standard. This packet has been ZLIB compressed, then Base64 encoded,
|
|
# then URLEncoded. In order to modify the inner XML you would need to peel off that encoding layers
|
|
# and then reaplly them in reversed order. This script allows you to do that in an automated manner
|
|
#
|
|
# NOTICE:
|
|
# If the input string's length is divisble by 4, Base64 will be able to decode it - thus, the script
|
|
# would wrongly assume it has been encoded using Base64. The same goes for Hex decoding.
|
|
# In order to tackle this issue, the script builds up a tree of possible encoding schemes and then evaluate
|
|
# that tree by choosing the best fitting encodings path (with most points counted upon resulted text's length,
|
|
# entropy and printable'ity).
|
|
#
|
|
# Requires:
|
|
# - jwt
|
|
# - anytree
|
|
#
|
|
# Mariusz B., 2018
|
|
#
|
|
|
|
import os
|
|
import re
|
|
import sys
|
|
import jwt
|
|
import zlib
|
|
import math
|
|
import base64
|
|
import urllib
|
|
import string
|
|
import anytree
|
|
import binascii
|
|
from collections import Counter
|
|
|
|
|
|
|
|
|
|
# =============================================
|
|
# RE-ENCODER'S IMPLEMENTATION
|
|
#
|
|
|
|
|
|
class ReEncoder:
|
|
|
|
# Switch this to show some verbose informations about decoding process.
|
|
DEBUG = True
|
|
|
|
PREFER_AUTO = 0 # Automatically determine final output format
|
|
PREFER_TEXT = 1 # Prefer text/printable final output format
|
|
PREFER_BINARY = 2 # Prefer binary final output format
|
|
|
|
class Utils:
|
|
@staticmethod
|
|
def isBinaryData(data):
|
|
nonBinary = 0
|
|
percOfBinaryToAssume = 0.10
|
|
|
|
for d in data:
|
|
c = ord(d)
|
|
if c in (10, 13):
|
|
nonBinary += 1
|
|
elif c >= 0x20 and c <= 0x7f:
|
|
nonBinary += 1
|
|
|
|
binary = len(data) - nonBinary
|
|
return binary >= int(percOfBinaryToAssume * len(data))
|
|
|
|
# ============================================================
|
|
# ENCODERS SECTION
|
|
#
|
|
|
|
class Encoder:
|
|
def name(self):
|
|
raise NotImplementedError
|
|
|
|
def check(self, data):
|
|
raise NotImplementedError
|
|
|
|
def encode(self, data):
|
|
raise NotImplementedError
|
|
|
|
def decode(self, data):
|
|
raise NotImplementedError
|
|
|
|
class NoneEncoder(Encoder):
|
|
def name(self):
|
|
return 'None'
|
|
|
|
def check(self, data):
|
|
if not data:
|
|
return False
|
|
return True
|
|
|
|
def encode(self, data):
|
|
return data
|
|
|
|
def decode(self, data):
|
|
return data
|
|
|
|
class URLEncoder(Encoder):
|
|
def name(self):
|
|
return 'URLEncoder'
|
|
|
|
def check(self, data):
|
|
if urllib.quote(urllib.unquote(data)) == data and (urllib.unquote(data) != data):
|
|
return True
|
|
|
|
if re.search(r'(?:%[0-9a-f]{2})+', data, re.I):
|
|
return True
|
|
|
|
return False
|
|
|
|
def encode(self, data):
|
|
return urllib.quote(data)
|
|
|
|
def decode(self, data):
|
|
return urllib.unquote(data)
|
|
|
|
class HexEncoder(Encoder):
|
|
def name(self):
|
|
return 'HexEncoded'
|
|
|
|
def check(self, data):
|
|
m = re.match(r'^[0-9a-f]+$', data, re.I)
|
|
if m:
|
|
return True
|
|
return False
|
|
|
|
def encode(self, data):
|
|
return binascii.hexlify(data).strip()
|
|
|
|
def decode(self, data):
|
|
return binascii.unhexlify(data).strip()
|
|
|
|
class Base64Encoder(Encoder):
|
|
def name(self):
|
|
return 'Base64'
|
|
|
|
def check(self, data):
|
|
try:
|
|
if base64.b64encode(base64.b64decode(data)) == data:
|
|
m = re.match('^(?:[A-Za-z0-9+\/]{4})*(?:[A-Za-z0-9+\/]{2}==|[A-Za-z0-9+\/]{3}=|[A-Za-z0-9+\/]{4})$', data, re.I)
|
|
if m:
|
|
return True
|
|
return False
|
|
except:
|
|
pass
|
|
return False
|
|
|
|
def encode(self, data):
|
|
return base64.b64encode(data)
|
|
|
|
def decode(self, data):
|
|
return base64.b64decode(data)
|
|
|
|
class Base64URLSafeEncoder(Encoder):
|
|
def name(self):
|
|
return 'Base64URLSafe'
|
|
|
|
def check(self, data):
|
|
try:
|
|
if base64.urlsafe_b64encode(base64.urlsafe_b64decode(data)) == data:
|
|
m = re.match('^(?:[A-Za-z0-9\-_]{4})*(?:[A-Za-z0-9\-_]{2}==|[A-Za-z0-9\-_]{3}=|[A-Za-z0-9\-_]{4})$', data, re.I)
|
|
if m:
|
|
return True
|
|
return False
|
|
except:
|
|
pass
|
|
return False
|
|
|
|
def encode(self, data):
|
|
return base64.urlsafe_b64encode(data)
|
|
|
|
def decode(self, data):
|
|
return base64.urlsafe_b64decode(data)
|
|
|
|
class JWTEncoder(Encoder):
|
|
secret = ''
|
|
|
|
def name(self):
|
|
return 'JWT'
|
|
|
|
def check(self, data):
|
|
try:
|
|
jwt.decode(data, verify = False)
|
|
return True
|
|
except jwt.exceptions.DecodeError:
|
|
return False
|
|
|
|
def encode(self, data):
|
|
return jwt.encode(data, JWTEncoder.secret)
|
|
|
|
def decode(self, data):
|
|
return jwt.decode(data, verify = False)
|
|
|
|
class ZlibEncoder(Encoder):
|
|
def name(self):
|
|
return 'ZLIB'
|
|
|
|
def check(self, data):
|
|
if not ReEncoder.Utils.isBinaryData(data):
|
|
return False
|
|
|
|
try:
|
|
if zlib.compress(zlib.decompress(data)) == data:
|
|
return True
|
|
except:
|
|
pass
|
|
return False
|
|
|
|
def encode(self, data):
|
|
return zlib.compress(data)
|
|
|
|
def decode(self, data):
|
|
return zlib.decompress(data)
|
|
|
|
|
|
|
|
# ============================================================
|
|
# ENCODING DETECTION IMPLEMENTATION
|
|
#
|
|
|
|
MaxEncodingDepth = 20
|
|
|
|
def __init__(self):
|
|
self.encodings = []
|
|
self.encoders = (
|
|
ReEncoder.URLEncoder(),
|
|
ReEncoder.HexEncoder(),
|
|
ReEncoder.Base64Encoder(),
|
|
ReEncoder.Base64URLSafeEncoder(),
|
|
ReEncoder.JWTEncoder(),
|
|
ReEncoder.ZlibEncoder(),
|
|
|
|
# None must always be the last detector
|
|
ReEncoder.NoneEncoder(),
|
|
)
|
|
self.encodersMap = {}
|
|
self.data = ''
|
|
self.preferredOutputFormat = ReEncoder.PREFER_AUTO
|
|
|
|
for encoder in self.encoders:
|
|
self.encodersMap[encoder.name()] = encoder
|
|
|
|
@staticmethod
|
|
def log(text):
|
|
if ReEncoder.DEBUG:
|
|
print(text)
|
|
|
|
def verifyEncodings(self, encodings):
|
|
for encoder in encodings:
|
|
if type(encoder) == str:
|
|
if not encoder in self.encodersMap.keys():
|
|
raise Exception("Passed unknown encoder's name.")
|
|
elif not issubclass(ReEncoder.Encoder, encoder):
|
|
raise Exception("Passed encoder is of unknown type.")
|
|
|
|
def generateEncodingTree(self, data):
|
|
step = 0
|
|
maxSteps = len(self.encoders) * ReEncoder.MaxEncodingDepth
|
|
|
|
peeledBefore = 0
|
|
peeledOff = 0
|
|
currData = data
|
|
|
|
while step < maxSteps:
|
|
peeledBefore = peeledOff
|
|
for encoder in self.encoders:
|
|
step += 1
|
|
|
|
ReEncoder.log('[.] Trying: {} (peeled off: {}). Current form: "{}"'.format(encoder.name(), peeledOff, currData))
|
|
|
|
if encoder.check(currData):
|
|
if encoder.name() == 'None':
|
|
continue
|
|
|
|
if encoder.name().lower().startswith('base64') and (len(currData) % 4 == 0):
|
|
ReEncoder.log('[.] Unclear situation whether input ({}) is Base64 encoded. Branching.'.format(
|
|
currData
|
|
))
|
|
|
|
yield ('None', currData, True)
|
|
|
|
if encoder.name().lower().startswith('hex') and (len(currData) % 2 == 0):
|
|
ReEncoder.log('[.] Unclear situation whether input ({}) is Hex encoded. Branching.'.format(
|
|
currData
|
|
))
|
|
|
|
yield ('None', currData, True)
|
|
|
|
ReEncoder.log('[+] Detected encoder: {}'.format(encoder.name()))
|
|
|
|
currData = encoder.decode(currData)
|
|
yield (encoder.name(), currData, False)
|
|
|
|
peeledOff += 1
|
|
|
|
break
|
|
|
|
if (peeledOff - peeledBefore) == 0:
|
|
break
|
|
|
|
def formEncodingCandidates(self, root):
|
|
iters = [[node for node in children] for children in anytree.LevelOrderGroupIter(root)]
|
|
|
|
candidates = []
|
|
|
|
for node in iters[-1]:
|
|
name = node.name
|
|
decoded = node.decoded
|
|
|
|
ReEncoder.log('[.] Candidate for best decode using {}: "{}"...'.format(
|
|
name, decoded[:20]
|
|
))
|
|
|
|
candidates.append([name, decoded, 0.0])
|
|
|
|
return candidates
|
|
|
|
@staticmethod
|
|
def entropy(data, unit='natural'):
|
|
base = {
|
|
'shannon' : 2.,
|
|
'natural' : math.exp(1),
|
|
'hartley' : 10.
|
|
}
|
|
|
|
if len(data) <= 1:
|
|
return 0
|
|
|
|
counts = Counter()
|
|
|
|
for d in data:
|
|
counts[d] += 1
|
|
|
|
probs = [float(c) / len(data) for c in counts.values()]
|
|
probs = [p for p in probs if p > 0.]
|
|
|
|
ent = 0
|
|
|
|
for p in probs:
|
|
if p > 0.:
|
|
ent -= p * math.log(p, base[unit])
|
|
|
|
return ent
|
|
|
|
def evaluateEncodingTree(self, root):
|
|
(printableEncodings, printableCandidate) = self.evaluateEncodingTreePicker(root, False)
|
|
(binaryEncodings, binaryCandidate) = self.evaluateEncodingTreePicker(root, True)
|
|
|
|
if self.preferredOutputFormat == ReEncoder.PREFER_TEXT:
|
|
ReEncoder.log('Returning text/printable output format as requested preferred one.')
|
|
return printableEncodings
|
|
elif self.preferredOutputFormat == ReEncoder.PREFER_BINARY:
|
|
ReEncoder.log('Returning binary output format as requested preferred one.')
|
|
return binaryEncodings
|
|
else:
|
|
ReEncoder.log('Trying to determine preferred output format...')
|
|
|
|
ReEncoder.log('\n---------------------------------------')
|
|
ReEncoder.log('[>] Winning printable encoding path scored: {} points.'.format(
|
|
printableCandidate[2]
|
|
))
|
|
ReEncoder.log('[>] Winning binary encoding path scored: {} points.'.format(
|
|
binaryCandidate[2]
|
|
))
|
|
|
|
if(printableCandidate[2] >= binaryCandidate[2]):
|
|
ReEncoder.log('\n[+] Choosing all-time winner: PRINTABLE output format.')
|
|
return printableEncodings
|
|
|
|
ReEncoder.log('\n[+] Choosing all-time winner: BINARY output format.')
|
|
ReEncoder.log('---------------------------------------\n')
|
|
return binaryEncodings
|
|
|
|
def evaluateEncodingTreePicker(self, root, preferBinary):
|
|
candidates = self._evaluateEncodingTreeWorker(root, preferBinary)
|
|
|
|
maxCandidate = 0
|
|
|
|
for i in range(len(candidates)):
|
|
candidate = candidates[i]
|
|
|
|
name = candidate[0]
|
|
decoded = candidate[1]
|
|
points = float(candidate[2])
|
|
|
|
if points > candidates[maxCandidate][2]:
|
|
maxCandidate = i
|
|
|
|
winningCandidate = candidates[maxCandidate]
|
|
winningPaths = anytree.search.findall_by_attr(
|
|
root,
|
|
name = 'decoded',
|
|
value = winningCandidate[1]
|
|
)
|
|
|
|
ReEncoder.log('[?] Other equally good candidate paths:\n' + str(winningPaths))
|
|
winningPath = winningPaths[0]
|
|
|
|
preferred = 'printable'
|
|
if preferBinary:
|
|
preferred = 'binary'
|
|
|
|
ReEncoder.log('[+] Winning decode path for {} output is:\n{}'.format(
|
|
preferred,
|
|
str(winningPath))
|
|
)
|
|
|
|
encodings = [x.name for x in winningPath.path if x != 'None']
|
|
return (encodings, winningCandidate)
|
|
|
|
def _evaluateEncodingTreeWorker(self, root, preferBinary = False):
|
|
weights = {
|
|
'unreadableChars' : 0.0,
|
|
'printableChars' : 9.6,
|
|
'entropyScore' : 4.0,
|
|
'length' : 1.0,
|
|
}
|
|
|
|
if preferBinary:
|
|
weights['unreadableChars'] = 24.0
|
|
weights['printableChars'] = 0.0
|
|
weights['entropyScore'] = 2.666667
|
|
|
|
candidates = self.formEncodingCandidates(root)
|
|
|
|
for i in range(len(candidates)):
|
|
candidate = candidates[i]
|
|
|
|
name = candidate[0]
|
|
decoded = candidate[1]
|
|
points = float(candidate[2])
|
|
entropy = ReEncoder.entropy(decoded)
|
|
printables = sum([int(x in string.printable) for x in decoded])
|
|
nonprintables = len(decoded) - printables
|
|
|
|
ReEncoder.log('[=] Evaluating candidate: {} (entropy: {}, data: "{}")'.format(
|
|
name, entropy, decoded
|
|
))
|
|
|
|
# Step 1: Adding points for printable percentage.
|
|
printablePoints = float(weights['printableChars']) * (float(printables) / float(len(decoded)))
|
|
nonPrintablePoints = float(weights['unreadableChars']) * (float(nonprintables) / float(len(decoded)))
|
|
|
|
# Step 2: If encoder is Base64 and was previously None
|
|
# - then length and entropy of previous values should be of slighly lower weights
|
|
if name.lower() == 'none' \
|
|
and len(candidates) > i+1 \
|
|
and candidates[i+1][0].lower().startswith('base64'):
|
|
ReEncoder.log('\tAdding fine for being base64')
|
|
entropyPoints = entropy * (weights['entropyScore'] * 0.666666)
|
|
lengthPoints = float(len(decoded)) * (weights['length'] * 0.666666)
|
|
else:
|
|
entropyPoints = entropy * weights['entropyScore']
|
|
lengthPoints = float(len(decoded)) * weights['length']
|
|
|
|
if printables > nonprintables:
|
|
ReEncoder.log('More printable chars than binary ones.')
|
|
ReEncoder.log('\tAdding {} points for printable entropy.'.format(entropyPoints))
|
|
|
|
ReEncoder.log('\tAdding {} points for printable characters.'.format(printablePoints))
|
|
points += printablePoints
|
|
else:
|
|
ReEncoder.log('More binary chars than printable ones.')
|
|
ReEncoder.log('\tAdding {} points for binary entropy.'.format(entropyPoints))
|
|
|
|
ReEncoder.log('\tAdding {} points for binary characters.'.format(nonPrintablePoints))
|
|
points += nonPrintablePoints
|
|
|
|
points += entropyPoints
|
|
|
|
# Step 4: Add points for length
|
|
ReEncoder.log('\tAdding {} points for length.'.format(lengthPoints))
|
|
points += lengthPoints
|
|
|
|
ReEncoder.log('\tScored in total: {} points.'.format(points))
|
|
candidates[i][2] = points
|
|
|
|
return candidates
|
|
|
|
|
|
def getWinningDecodePath(self, root):
|
|
return [x for x in self.evaluateEncodingTree(root) if x != 'None']
|
|
|
|
def process(self, data):
|
|
root = anytree.Node('None', decoded = data)
|
|
prev = root
|
|
|
|
for (name, curr, branch) in self.generateEncodingTree(data):
|
|
ReEncoder.log('[*] Generator returned: ("{}", "{}", {})'.format(
|
|
name, curr[:20], str(branch)
|
|
))
|
|
|
|
currNode = anytree.Node(name, parent = prev, decoded = curr)
|
|
if branch:
|
|
pass
|
|
else:
|
|
prev = currNode
|
|
|
|
for pre, fill, node in anytree.RenderTree(root):
|
|
if node.name != 'None':
|
|
ReEncoder.log("%s%s (%s)" % (pre, node.name, node.decoded[:20].decode('ascii', 'ignore')))
|
|
|
|
self.encodings = self.getWinningDecodePath(root)
|
|
ReEncoder.log('[+] Selected encodings: {}'.format(str(self.encodings)))
|
|
|
|
def decode(self, data, preferredOutputFormat = PREFER_AUTO, encodings = []):
|
|
self.preferredOutputFormat = preferredOutputFormat
|
|
|
|
if preferredOutputFormat != ReEncoder.PREFER_AUTO and \
|
|
preferredOutputFormat != ReEncoder.PREFER_TEXT and \
|
|
preferredOutputFormat != ReEncoder.PREFER_BINARY:
|
|
raise Exception('Unknown preferred output format specified in decode(): {}'.format(
|
|
preferredOutputFormat
|
|
))
|
|
|
|
if not encodings:
|
|
self.process(data)
|
|
else:
|
|
self.verifyEncodings(encodings)
|
|
self.encodings = encodings
|
|
|
|
for encoderName in self.encodings:
|
|
d = self.encodersMap[encoderName].decode(data)
|
|
data = d
|
|
|
|
return data
|
|
|
|
def encode(self, data, encodings = []):
|
|
if encodings:
|
|
encodings.reverse()
|
|
self.verifyEncodings(encodings)
|
|
self.encodings = encodings
|
|
|
|
for encoderName in self.encodings[::-1]:
|
|
e = self.encodersMap[encoderName].encode(data)
|
|
data = e
|
|
|
|
return data
|
|
|
|
|
|
def main(argv):
|
|
# Sample 1: ZLIB -> Base64 -> URLEncode
|
|
sample = 'eJzzSM3JyVcozy%2FKSVFIK8rPVQhKdc1Lzk9JLVIEAIr8Cck%3D'
|
|
|
|
# Sample 2: URLEncode -> Base64 -> HexEncode
|
|
#sample = '4a5451344a5459314a545a6a4a545a6a4a545a6d4a5449774a5463334a545a6d4a5463794a545a6a4a5459304a5449784a5449774a544e684a544a6b4a544935'
|
|
|
|
if len(argv) != 2:
|
|
print('Usage: reencode.py <text|file>')
|
|
print('Using sample: "{}"'.format(sample))
|
|
text = sample
|
|
else:
|
|
text = argv[1]
|
|
|
|
if os.path.isfile(text):
|
|
f = open(text, 'rb')
|
|
text = f.read()
|
|
f.close()
|
|
|
|
decoder = ReEncoder()
|
|
decoded = decoder.decode(text)
|
|
|
|
print('(1) DECODED TEXT: "{}"'.format(decoded))
|
|
|
|
decoded = 'FOO ' + decoded + ' BAR'
|
|
|
|
print('\n(2) TO BE ENCODED TEXT: "{}"'.format(decoded))
|
|
|
|
decoded = decoder.encode(decoded)
|
|
print('(3) ENCODED FORM: "{}"'.format(decoded))
|
|
|
|
if __name__ == '__main__':
|
|
main(sys.argv)
|