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size intolerance checks

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since TLSv1.3 client hello's will include initial client key share,
verify that the server is able to accept and process big client hello
messages
This commit is contained in:
Hubert Kario 2016-08-04 22:39:34 +02:00
parent 88ae052f8e
commit 1f26852b29
3 changed files with 507 additions and 0 deletions
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77
cscan.py
View File

@ -20,6 +20,7 @@ from cscan.config import Xmas_tree, IE_6, IE_8_Win_XP, \
from cscan.modifiers import no_sni, set_hello_version, set_record_version, \
no_extensions, truncate_ciphers_to_size, append_ciphers_to_size, \
extend_with_ext_to_size, add_empty_ext
from cscan.bisector import Bisect
def scan_with_config(host, port, conf, hostname, __sentry=None, __cache={}):
@ -291,6 +292,82 @@ def scan_TLS_intolerancies(host, port, hostname):
conf.extensions and not
conf.ssl2))
#for name in ["Xmas tree", "Huge Cipher List",
# "Huge Cipher List (trunc c/16388)"]:
# intolerancies[name] = all(conf_iterator(lambda conf:
# conf.name == name))
def test_cb(client_hello):
ret = scan_with_config(host, port, lambda _:client_hello, hostname)
return simple_inspector(ret)
# most size intolerancies lie between 16385 and 16389 so short-circuit to
# them if possible
good_conf = next((configs[name] for name, result in results.items()
if simple_inspector(result)), None)
if good_conf:
size_c_16382 = simple_inspector(scan_with_config(host, port,
append_ciphers_to_size(copy.deepcopy(good_conf), 16382), hostname))
size_c_16392 = simple_inspector(scan_with_config(host, port,
append_ciphers_to_size(copy.deepcopy(good_conf), 16392), hostname))
if size_c_16382 and not size_c_16392:
good = append_ciphers_to_size(copy.deepcopy(good_conf), 16382)
bad = append_ciphers_to_size(copy.deepcopy(good_conf), 16392)
elif not size_c_16382:
good = good_conf
bad = append_ciphers_to_size(copy.deepcopy(good_conf), 16382)
else:
bad = append_ciphers_to_size(copy.deepcopy(good_conf), 65536)
size_c_65536 = simple_inspector(scan_with_config(host, port,
bad, hostname))
if not size_c_65536:
good = None
intolerancies["size c/65536"] = False
else:
good = append_ciphers_to_size(copy.deepcopy(good_conf), 16392)
if good:
bisect = Bisect(good, bad, hostname, test_cb)
good_h, bad_h = bisect.run()
intolerancies["size c/{0}".format(len(bad_h.write()))] = True
intolerancies["size c/{0}".format(len(good_h.write()))] = False
# test extension size intolerance, again, most lie between 16385
# and 16389 so short-circuit if possible
good_conf = next((configs[name] for name, result in results.items()
if configs[name].extensions and
simple_inspector(result)), None)
if good_conf:
size_e_16382 = simple_inspector(scan_with_config(host, port,
extend_with_ext_to_size(copy.deepcopy(good_conf), 16382), hostname))
size_e_16392 = simple_inspector(scan_with_config(host, port,
extend_with_ext_to_size(copy.deepcopy(good_conf), 16392), hostname))
if size_e_16382 and not size_e_16392:
good = extend_with_ext_to_size(copy.deepcopy(good_conf), 16382)
bad = extend_with_ext_to_size(copy.deepcopy(good_conf), 16392)
elif not size_e_16382:
good = good_conf
bad = extend_with_ext_to_size(copy.deepcopy(good_conf), 16382)
else:
bad = extend_with_ext_to_size(copy.deepcopy(good_conf), 65536)
size_e_65536 = simple_inspector(scan_with_config(host, port,
bad, hostname))
if not size_e_65536:
good = None
intolerancies["size e/65536"] = False
else:
good = extend_with_ext_to_size(copy.deepcopy(good_conf), 16392)
if good:
bisect = Bisect(good, bad, hostname, test_cb)
good_h, bad_h = bisect.run()
intolerancies["size e/{0}".format(len(bad_h.write()))] = True
intolerancies["size e/{0}".format(len(good_h.write()))] = False
if json_out:
print(json.dumps(intolerancies))
else:

172
cscan/bisector.py Normal file
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@ -0,0 +1,172 @@
# Copyright (c) 2015 Hubert Kario <hkario@redhat.com>
# Released under Mozilla Public License Version 2.0
"""Find an itolerance through bisecting Client Hello"""
import copy
from tlslite.extensions import PaddingExtension
def list_union(first, second):
"""Return an union between two lists, preserving order"""
first_i = iter(first)
second_i = iter(second)
first_s = set(first)
second_s = set(second)
ret = []
first_el = next(first_i, None)
second_el = next(second_i, None)
while first_el is not None and second_el is not None:
if first_el != second_el:
if first_el in second_s and second_el in first_s:
# the second list is longer, so take from it
ret.append(second_el)
# no discard as we would have duplicates
second_el = next(second_i, None)
continue
if first_el not in second_s:
ret.append(first_el)
first_s.discard(first_el)
first_el = next(first_i, None)
if second_el not in first_s:
ret.append(second_el)
second_s.discard(second_el)
second_el = next(second_i, None)
else:
ret.append(first_el)
first_s.discard(first_el)
second_s.discard(first_el)
first_el = next(first_i, None)
second_el = next(second_i, None)
while first_el:
if first_el not in second_s:
ret.append(first_el)
first_el = next(first_i, None)
while second_el:
if second_el not in first_s:
ret.append(second_el)
second_el = next(second_i, None)
return ret
def bisect_lists(first, second):
"""Return a list that is in the "middle" between the given ones"""
# handle None special cases
if first is None and second is None:
return None
if first is not None and second is None:
first, second = second, first
if first is None and second is not None:
if len(second) == 0:
return None
elif len(second) == 1:
return []
else:
first = []
# make the second lists always the longer one
if len(first) > len(second):
second, first = first, second
first_s = set(first)
second_s = set(second)
union = list_union(first, second)
symmetric_diff = first_s.symmetric_difference(second_s)
# preserve order for the difference
symmetric_diff = [x for x in union if x in symmetric_diff]
half_diff = set(symmetric_diff[:len(symmetric_diff)//2])
intersection = first_s & second_s
return [x for x in union if x in half_diff or x in intersection]
def bisect_padding_extension(first, second):
if first is None and second is None:
return None
if first is not None and second is None:
first, second = second, first
if first is None and second is not None:
if len(second.paddingData) == 0:
return None
elif len(second.paddingData) == 1:
return PaddingExtension()
else:
first = PaddingExtension()
return PaddingExtension().create((len(first.paddingData) +
len(second.paddingData)) // 2)
def bisect_extensions(first, second):
# handle padding extension
if first is None and second is None:
return None
if first is not None and second is None:
first, second = second, first
if first is None and second is not None:
if len(second) == 0:
return None
if len(second) == 1:
return []
first = []
f_ext = next((x for x in first if isinstance(x, PaddingExtension)), None)
s_ext = next((x for x in second if isinstance(x, PaddingExtension)), None)
ext = bisect_padding_extension(f_ext, s_ext)
if ext is None:
# remove the extension
return [x for x in first if not isinstance(x, PaddingExtension)]
else:
if f_ext is None:
return first + [ext]
# replace extension
return [ext if isinstance(x, PaddingExtension) else x for x in first]
def bisect_hellos(first, second):
"""Return a client hello that is in the "middle" of two other"""
ret = copy.copy(first)
ret.client_version = ((first.client_version[0] + second.client_version[0])
// 2,
(first.client_version[1] + second.client_version[1])
// 2)
ret.cipher_suites = bisect_lists(first.cipher_suites, second.cipher_suites)
ret.extensions = bisect_lists(first.extensions, second.extensions)
ret.compression_methods = bisect_lists(first.compression_methods,
second.compression_methods)
if first.extensions == ret.extensions \
or second.extensions == ret.extensions:
ret.extensions = bisect_extensions(first.extensions,
second.extensions)
return ret
class Bisect(object):
"""
Perform a bisection between two Client Hello's to find intolerance
Tries to find a cause for intolerance by using a bisection-like
algorithm
"""
def __init__(self, good, bad, hostname, callback):
"""Set the generators for good and bad hello's and callback to test"""
self.good = good
self.bad = bad
if hostname is not None:
self.hostname = bytearray(hostname, 'utf-8')
else:
self.hostname = None
self.callback = callback
def run(self):
good_hello = self.good(self.hostname)
bad_hello = self.bad(self.hostname)
middle = bisect_hellos(good_hello, bad_hello)
while good_hello != middle and \
middle != bad_hello:
if self.callback(middle):
good_hello = middle
else:
bad_hello = middle
middle = bisect_hellos(good_hello, bad_hello)
return (good_hello, bad_hello)

258
cscan_tests/test_bisector.py Normal file
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@ -0,0 +1,258 @@
# Copyright (c) 2015 Hubert Kario
# Released under Mozilla Public License Version 2.0
try:
import unittest2 as unittest
except ImportError:
import unittest
from tlslite.extensions import SignatureAlgorithmsExtension, SNIExtension, \
SupportedGroupsExtension, ECPointFormatsExtension, TLSExtension
from cscan.config import HugeCipherList, VeryCompatible, IE_8_Win_XP
from cscan.bisector import bisect_lists, list_union, Bisect
from cscan.modifiers import extend_with_ext_to_size, append_ciphers_to_size
class TestListUnion(unittest.TestCase):
def test_identical(self):
a = [1, 2, 3, 4]
b = [1, 2, 3, 4]
c = list_union(a, b)
self.assertEqual(c, [1, 2, 3, 4])
def test_extended(self):
a = [1, 2, 3, 4]
b = [1, 2, 3, 4, 5, 6, 7, 8]
c = list_union(a, b)
self.assertEqual(c, [1, 2, 3, 4, 5, 6, 7, 8])
def test_extended_reversed(self):
a = [1, 2, 3, 4, 5, 6, 7, 8]
b = [1, 2, 3, 4]
c = list_union(a, b)
self.assertEqual(c, [1, 2, 3, 4, 5, 6, 7, 8])
def test_prepended(self):
a = [5, 6, 7, 8]
b = [1, 2, 3, 4, 5, 6, 7, 8]
c = list_union(a, b)
self.assertEqual(c, [1, 2, 3, 4, 5, 6, 7, 8])
def test_mixed(self):
a = [1, 2, 3, 4]
b = [5, 1, 2, 6, 4]
c = list_union(a, b)
self.assertEqual(c, [5, 1, 2, 3, 6, 4])
def test_mixed_reversed(self):
a = [5, 1, 2, 6, 4]
b = [1, 2, 3, 4]
c = list_union(a, b)
self.assertEqual(c, [5, 1, 2, 6, 3, 4])
def test_different_order(self):
a = [1, 2, 3, 4]
b = [2, 3, 1, 4]
c = list_union(a, b)
self.assertEqual(c, [2, 3, 1, 4])
def test_different_order2(self):
a = [1, 2, 3, 4, 5, 6]
b = [3, 1, 4, 2, 5, 6]
c = list_union(a, b)
self.assertEqual(c, [3, 1, 4, 2, 5, 6])
def test_different_order_superset(self):
a = [1, 2, 3, 4]
b = [4, 3, 1, 2, 5, 6]
c = list_union(a, b)
self.assertEqual(c, [4, 3, 1, 2, 5, 6])
def test_completely_disjoint(self):
a = [1, 2, 3, 4]
b = [5, 6, 7, 8]
c = list_union(a, b)
self.assertEqual(c, [1, 5, 2, 6, 3, 7, 4, 8])
def test_different_suffix(self):
a = [1, 2, 3, 4]
b = [1, 2, 5, 6]
c = list_union(a, b)
self.assertEqual(c, [1, 2, 3, 5, 4, 6])
def test_different_prefix(self):
a = [1, 2, 3, 4]
b = [5, 6, 3, 4]
c = list_union(a, b)
self.assertEqual(c, [1, 5, 2, 6, 3, 4])
def test_one_empty(self):
a = [1, 2, 3, 4]
b = []
c = list_union(a, b)
self.assertEqual(c, [1, 2, 3, 4])
def test_both_empty(self):
a = []
b = []
c = list_union(a, b)
self.assertEqual(c, [])
class TestBisectLists(unittest.TestCase):
def test_sorted(self):
a = [1, 5, 7, 9]
b = [3, 5, 6, 8]
c = bisect_lists(a, b)
self.assertEqual(c, [1, 3, 5, 7])
d = bisect_lists(c, b)
self.assertEqual(d, [1, 3, 5, 7])
e = bisect_lists(a, c)
self.assertEqual(e, [1, 3, 5, 7])
def test_extended(self):
a = [1, 2, 3, 4]
b = [1, 2, 3, 4, 5, 6, 7, 8]
c = bisect_lists(a, b)
self.assertEqual(a, [1, 2, 3, 4])
self.assertEqual(b, [1, 2, 3, 4, 5, 6, 7, 8])
self.assertEqual(c, [1, 2, 3, 4, 5, 6])
d = bisect_lists(c, b)
self.assertEqual(d, [1, 2, 3, 4, 5, 6, 7])
def test_extended_reversed(self):
a = [1, 2, 3, 4, 5, 6, 7, 8]
b = [1, 2, 3, 4]
c = bisect_lists(a, b)
self.assertEqual(a, [1, 2, 3, 4, 5, 6, 7, 8])
self.assertEqual(b, [1, 2, 3, 4])
self.assertEqual(c, [1, 2, 3, 4, 5, 6])
def test_prepended(self):
a = [5, 6, 7, 8]
b = [1, 2, 3, 4, 5, 6, 7, 8]
c = bisect_lists(a, b)
self.assertEqual(c, [1, 2, 5, 6, 7, 8])
def test_both_different(self):
a = [1, 2, 3, 4]
b = [1, 2, 5, 6]
c = bisect_lists(a, b)
self.assertEqual(c, [1, 2, 3, 5])
def test_small_difference(self):
a = [1, 2, 3, 4]
b = [1, 2, 3, 5]
c = bisect_lists(a, b)
self.assertEqual(c, [1, 2, 3, 4])
def test_small_difference_with_different_order(self):
a = [2, 3, 1, 4]
b = [1, 2, 3, 5]
c = bisect_lists(a, b)
self.assertEqual(c, [1, 2, 3, 5])
def test_one_empty(self):
a = []
b = [1, 2, 3, 4]
c = bisect_lists(a, b)
self.assertEqual(c, [1, 2])
def test_both_empty(self):
a = []
b = []
c = bisect_lists(a, b)
self.assertEqual(c, [])
def test_one_None(self):
a = None
b = [1, 2, 3, 4]
c = bisect_lists(a, b)
self.assertEqual(c, [1, 2])
def test_short_and_None(self):
a = None
b = [1]
c = bisect_lists(a, b)
self.assertEqual(c, [])
def test_empty_and_None(self):
a = None
b = []
c = bisect_lists(a, b)
self.assertEqual(c, None)
class TestBisect(unittest.TestCase):
def test___init__(self):
b = Bisect(None, None, None, None)
self.assertIsNotNone(b)
def test_run(self):
def test_cb(hello):
return len(hello.write()) <= 2**14
bad = HugeCipherList()
good = VeryCompatible()
self.assertGreater(len(bad(b'').write()), 2**14)
self.assertLess(len(good(b'').write()), 2**14)
bi = Bisect(good, bad, "localhost", test_cb)
a, b = bi.run()
self.assertEqual(len(a.write()), 2**14-1)
self.assertEqual(len(b.write()), 2**14+1)
def test_run_with_extensions(self):
def test_cb(hello):
if not hello.extensions:
return True
a = next((x for x in hello.extensions
if isinstance(x, SignatureAlgorithmsExtension)), None)
return a is None
good = IE_8_Win_XP()
bad = VeryCompatible()
self.assertTrue(test_cb(good(b'localhost')))
self.assertFalse(test_cb(bad(b'localhost')))
bi = Bisect(good, bad, "localhost", test_cb)
a, b = bi.run()
ext = next((x for x in a.extensions
if isinstance(x, SignatureAlgorithmsExtension)), None)
self.assertIsNone(ext)
ext = next((x for x in b.extensions
if isinstance(x, SignatureAlgorithmsExtension)), None)
self.assertIsNotNone(ext)
def test_run_with_extension_size(self):
def test_cb(hello):
return len(hello.write()) <= 2**14
bad = extend_with_ext_to_size(VeryCompatible(), 2**16)
good = VeryCompatible()
bi = Bisect(good, bad, "localhost", test_cb)
a, b = bi.run()
self.assertEqual(len(a.write()), 2**14)
self.assertEqual(len(b.write()), 2**14+1)
def test_run_with_ext_and_ciphers(self):
def test_cb(hello):
return len(hello.write()) <= 2**14
bad = extend_with_ext_to_size(VeryCompatible(), 2**15)
bad = append_ciphers_to_size(bad, 2**16)
good = VeryCompatible()
bi = Bisect(good, bad, "localhost", test_cb)
a, b = bi.run()
self.assertEqual(len(a.write()), 2**14)
self.assertEqual(len(b.write()), 2**14+1)