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Fixed merge collision in connect() method.

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This commit is contained in:
Joe Testa 2017-10-31 16:40:02 -04:00
commit 95ca0bb243
1 changed files with 673 additions and 33 deletions
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ssh-audit.py
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@ -24,7 +24,7 @@
THE SOFTWARE.
"""
from __future__ import print_function
import os, io, sys, socket, struct, random, errno, getopt, re, hashlib, base64
import binascii, os, io, sys, socket, struct, random, errno, getopt, re, hashlib, base64
VERSION = 'v1.7.1.dev'
@ -299,7 +299,6 @@ class SSH2(object): # pylint: disable=too-few-public-methods
WARN_CURVES_WEAK = 'using weak elliptic curves'
WARN_RNDSIG_KEY = 'using weak random number generator could reveal the key'
WARN_MODULUS_SIZE = 'using small 1024-bit modulus'
WARN_MODULUS_CUSTOM = 'using custom size modulus (possibly weak)'
WARN_HASH_WEAK = 'using weak hashing algorithm'
WARN_CIPHER_MODE = 'using weak cipher mode'
WARN_BLOCK_SIZE = 'using small 64-bit block size'
@ -316,7 +315,7 @@ class SSH2(object): # pylint: disable=too-few-public-methods
'diffie-hellman-group16-sha512': [['7.3,d2016.73']],
'diffie-hellman-group18-sha512': [['7.3']],
'diffie-hellman-group-exchange-sha1': [['2.3.0', '6.6', None], [FAIL_OPENSSH67_UNSAFE], [WARN_HASH_WEAK]],
'diffie-hellman-group-exchange-sha256': [['4.4'], [], [WARN_MODULUS_CUSTOM]],
'diffie-hellman-group-exchange-sha256': [['4.4']],
'ecdh-sha2-nistp256': [['5.7,d2013.62,l10.6.0'], [WARN_CURVES_WEAK]],
'ecdh-sha2-nistp384': [['5.7,d2013.62'], [WARN_CURVES_WEAK]],
'ecdh-sha2-nistp521': [['5.7,d2013.62'], [WARN_CURVES_WEAK]],
@ -445,7 +444,10 @@ class SSH2(object): # pylint: disable=too-few-public-methods
self.__server = srv
self.__follows = follows
self.__unused = unused
self.__rsa_key_sizes = {}
self.__dh_modulus_sizes = {}
@property
def cookie(self):
# type: () -> binary_type
@ -482,7 +484,19 @@ class SSH2(object): # pylint: disable=too-few-public-methods
def unused(self):
# type: () -> int
return self.__unused
def set_rsa_key_size(self, rsa_type, hostkey_size, ca_size=-1):
self.__rsa_key_sizes[rsa_type] = (hostkey_size, ca_size)
def rsa_key_sizes(self):
return self.__rsa_key_sizes
def set_dh_modulus_size(self, gex_alg, modulus_size):
self.__dh_modulus_sizes[gex_alg] = (modulus_size, -1)
def dh_modulus_sizes(self):
return self.__dh_modulus_sizes
def write(self, wbuf):
# type: (WriteBuf) -> None
wbuf.write(self.cookie)
@ -528,6 +542,242 @@ class SSH2(object): # pylint: disable=too-few-public-methods
kex = cls(cookie, kex_algs, key_algs, cli, srv, follows, unused)
return kex
# Obtains RSA host keys and checks their size.
class RSAKeyTest(object):
RSA_TYPES = ['ssh-rsa', 'rsa-sha2-256', 'rsa-sha2-512']
RSA_CA_TYPES = ['ssh-rsa-cert-v01@openssh.com']
@staticmethod
def run(s, server_kex):
KEX_TO_DHGROUP = {
'diffie-hellman-group1-sha1': KexGroup1,
'diffie-hellman-group14-sha1': KexGroup14_SHA1,
'diffie-hellman-group14-sha256': KexGroup14_SHA256,
'curve25519-sha256': KexCurve25519_SHA256,
'curve25519-sha256@libssh.org': KexCurve25519_SHA256,
'diffie-hellman-group16-sha512': KexGroup16_SHA512,
'diffie-hellman-group18-sha512': KexGroup18_SHA512,
'diffie-hellman-group-exchange-sha1': KexGroupExchange_SHA1,
'diffie-hellman-group-exchange-sha256': KexGroupExchange_SHA256,
'ecdh-sha2-nistp256': KexNISTP256,
'ecdh-sha2-nistp384': KexNISTP384,
'ecdh-sha2-nistp521': KexNISTP521,
#'kexguess2@matt.ucc.asn.au': ???
}
# Pick the first kex algorithm that the server supports, which we
# happen to support as well.
kex_str = None
kex_group = None
for server_kex_alg in server_kex.kex_algorithms:
if server_kex_alg in KEX_TO_DHGROUP:
kex_str = server_kex_alg
kex_group = KEX_TO_DHGROUP[kex_str]()
break
if kex_str is not None:
SSH2.RSAKeyTest.__test(s, server_kex, kex_str, kex_group, SSH2.RSAKeyTest.RSA_TYPES)
SSH2.RSAKeyTest.__test(s, server_kex, kex_str, kex_group, SSH2.RSAKeyTest.RSA_CA_TYPES, ca=True)
@staticmethod
def __test(s, server_kex, kex_str, kex_group, rsa_types, ca=False):
# If the server supports one of the RSA types, extract its key size.
hostkey_modulus_size = 0
ca_modulus_size = 0
ran_test = False
# If the connection is closed, re-open it and get the kex again.
if not s.is_connected():
s.connect()
unused = None # pylint: disable=unused-variable
unused, unused, err = s.get_banner()
if err is not None:
s.close()
return
# Parse the server's initial KEX.
packet_type = 0 # pylint: disable=unused-variable
packet_type, payload = s.read_packet()
SSH2.Kex.parse(payload)
for rsa_type in rsa_types:
if rsa_type in server_kex.key_algorithms:
ran_test = True
# Send the server our KEXINIT message, using only our
# selected kex and RSA type. Send the server's own
# list of ciphers and MACs back to it (this doesn't
# matter, really).
client_kex = SSH2.Kex(os.urandom(16), [kex_str], [rsa_type], server_kex.client, server_kex.server, 0, 0)
s.write_byte(SSH.Protocol.MSG_KEXINIT)
client_kex.write(s)
s.send_packet()
# Do the initial DH exchange. The server responds back
# with the host key and its length. Bingo.
kex_group.send_init(s)
kex_group.recv_reply(s)
hostkey_modulus_size = kex_group.get_hostkey_size()
ca_modulus_size = kex_group.get_ca_size()
# If we're not working with the CA types, we only need to
# test one RSA key, since the others will all be the same.
if ca is False:
break
if hostkey_modulus_size > 0 or ca_modulus_size > 0:
# Set the hostkey size for all RSA key types since 'ssh-rsa',
# 'rsa-sha2-256', etc. are all using the same host key.
# Note, however, that this may change in the future.
if ca is False:
for rsa_type in rsa_types:
server_kex.set_rsa_key_size(rsa_type, hostkey_modulus_size)
else:
server_kex.set_rsa_key_size(rsa_type, hostkey_modulus_size, ca_modulus_size)
# Keys smaller than 2048 result in a failure.
fail = False
if hostkey_modulus_size < 2048 or (ca_modulus_size < 2048 and ca_modulus_size > 0):
fail = True
# If this is a bad key size, update the database accordingly.
if fail:
if ca is False:
for rsa_type in SSH2.RSAKeyTest.RSA_TYPES:
alg_list = SSH2.KexDB.ALGORITHMS['key'][rsa_type]
alg_list.append(['using small %d-bit modulus' % hostkey_modulus_size])
else:
alg_list = SSH2.KexDB.ALGORITHMS['key'][rsa_type]
min_modulus = min(hostkey_modulus_size, ca_modulus_size)
min_modulus = min_modulus if min_modulus > 0 else max(hostkey_modulus_size, ca_modulus_size)
alg_list.append(['using small %d-bit modulus' % min_modulus])
# If we ran any tests, close the socket, as the connection has
# been put in a state that later tests can't use.
if ran_test:
s.close()
# Performs DH group exchanges to find what moduli are supported, and checks
# their size.
class GEXTest(object):
# Creates a new connection to the server. Returns an SSH.Socket, or
# None on failure.
@staticmethod
def reconnect(s, gex_alg):
if s.is_connected():
return
s.connect()
unused = None # pylint: disable=unused-variable
unused, unused, err = s.get_banner()
if err is not None:
s.close()
return False
# Parse the server's initial KEX.
packet_type = 0 # pylint: disable=unused-variable
packet_type, payload = s.read_packet(2)
kex = SSH2.Kex.parse(payload)
# Send our KEX using the specified group-exchange and most of the
# server's own values.
client_kex = SSH2.Kex(os.urandom(16), [gex_alg], kex.key_algorithms, kex.client, kex.server, 0, 0)
s.write_byte(SSH.Protocol.MSG_KEXINIT)
client_kex.write(s)
s.send_packet()
return True
# Runs the DH moduli test against the specified target.
@staticmethod
def run(s, kex):
GEX_ALGS = {
'diffie-hellman-group-exchange-sha1': KexGroupExchange_SHA1,
'diffie-hellman-group-exchange-sha256': KexGroupExchange_SHA256,
}
# The previous RSA tests put the server in a state we can't
# test. So we need a new connection to start with a clean
# slate.
if s.is_connected():
s.close()
# Check if the server supports any of the group-exchange
# algorithms. If so, test each one.
for gex_alg in GEX_ALGS:
if gex_alg in kex.kex_algorithms:
if SSH2.GEXTest.reconnect(s, gex_alg) is False:
break
kex_group = GEX_ALGS[gex_alg]()
smallest_modulus = -1
# First try a range of weak sizes.
try:
kex_group.send_init_gex(s, 512, 1024, 1536)
kex_group.recv_reply(s)
# Its been observed that servers will return a group
# larger than the requested max. So just because we
# got here, doesn't mean the server is vulnerable...
smallest_modulus = kex_group.get_dh_modulus_size()
except Exception: # pylint: disable=bare-except
x = 1 # pylint: disable=unused-variable
finally:
s.close()
# Try an array of specific modulus sizes... one at a time.
reconnect_failed = False
for bits in [512, 768, 1024, 1536, 2048, 3072, 4096]:
# If we found one modulus size already, but we're about
# to test a larger one, don't bother.
if smallest_modulus > 0 and bits >= smallest_modulus:
break
if SSH2.GEXTest.reconnect(s, gex_alg) is False:
reconnect_failed = True
break
try:
kex_group.send_init_gex(s, bits, bits, bits)
kex_group.recv_reply(s)
smallest_modulus = kex_group.get_dh_modulus_size()
except Exception: # pylint: disable=bare-except
x = 1 # pylint: disable=unused-variable
finally:
# The server is in a state that is not re-testable,
# so there's nothing else to do with this open
# connection.
s.close()
if smallest_modulus > 0:
kex.set_dh_modulus_size(gex_alg, smallest_modulus)
# We flag moduli smaller than 2048 as a failure.
if smallest_modulus < 2048:
text = 'using small %d-bit modulus' % smallest_modulus
lst = SSH2.KexDB.ALGORITHMS['kex'][gex_alg]
# For 'diffie-hellman-group-exchange-sha256', add
# a failure reason.
if len(lst) == 1:
lst.append([text])
# For 'diffie-hellman-group-exchange-sha1', delete
# the existing failure reason (which is vague), and
# insert our own.
else:
del lst[1]
lst.insert(1, [text])
if reconnect_failed:
break
class SSH1(object):
class CRC32(object):
@ -794,6 +1044,10 @@ class ReadBuf(object):
# type: () -> text_type
return self._buf.readline().rstrip().decode('utf-8', 'replace')
def reset(self):
self._buf = BytesIO()
self._len = 0
super(ReadBuf, self).reset()
class WriteBuf(object):
def __init__(self, data=None):
@ -883,6 +1137,9 @@ class WriteBuf(object):
self._wbuf.seek(0)
return payload
def reset(self):
self._wbuf = BytesIO()
class SSH(object): # pylint: disable=too-few-public-methods
class Protocol(object): # pylint: disable=too-few-public-methods
@ -891,7 +1148,11 @@ class SSH(object): # pylint: disable=too-few-public-methods
MSG_KEXINIT = 20
MSG_NEWKEYS = 21
MSG_KEXDH_INIT = 30
MSG_KEXDH_REPLY = 32
MSG_KEXDH_REPLY = 31
MSG_KEXDH_GEX_REQUEST = 34
MSG_KEXDH_GEX_GROUP = 31
MSG_KEXDH_GEX_INIT = 32
MSG_KEXDH_GEX_REPLY = 33
class Product(object): # pylint: disable=too-few-public-methods
OpenSSH = 'OpenSSH'
@ -1382,10 +1643,8 @@ class SSH(object): # pylint: disable=too-few-public-methods
for alg_type, alg_list in alg_pair.items():
if alg_type == 'aut':
continue
rec[sshv][alg_type] = {'add': {}, 'del': {}}
rec[sshv][alg_type] = {'add': {}, 'del': {}, 'chg': {}}
for n, alg_desc in alg_db[alg_type].items():
if alg_type == 'key' and '-cert-' in n:
continue
versions = alg_desc[0]
if len(versions) == 0 or versions[0] is None:
continue
@ -1412,18 +1671,19 @@ class SSH(object): # pylint: disable=too-few-public-methods
if fc > 0:
faults += pow(10, 2 - i) * fc
if n not in alg_list:
if faults > 0:
if faults > 0 or (alg_type == 'key' and '-cert-' in n):
continue
rec[sshv][alg_type]['add'][n] = 0
else:
if faults == 0:
continue
if n == 'diffie-hellman-group-exchange-sha256':
if software.compare_version('7.3') < 0:
continue
rec[sshv][alg_type]['del'][n] = faults
if n in ['diffie-hellman-group-exchange-sha256', 'ssh-rsa', 'rsa-sha2-256', 'rsa-sha2-512', 'ssh-rsa-cert-v01@openssh.com']:
rec[sshv][alg_type]['chg'][n] = faults
else:
rec[sshv][alg_type]['del'][n] = faults
add_count = len(rec[sshv][alg_type]['add'])
del_count = len(rec[sshv][alg_type]['del'])
chg_count = len(rec[sshv][alg_type]['chg'])
new_alg_count = len(alg_list) + add_count - del_count
if new_alg_count < 1 and del_count > 0:
mf = min(rec[sshv][alg_type]['del'].values())
@ -1441,6 +1701,8 @@ class SSH(object): # pylint: disable=too-few-public-methods
del rec[sshv][alg_type]['add']
if del_count == 0:
del rec[sshv][alg_type]['del']
if chg_count == 0:
del rec[sshv][alg_type]['chg']
if len(rec[sshv][alg_type]) == 0:
del rec[sshv][alg_type]
if len(rec[sshv]) == 0:
@ -1585,6 +1847,7 @@ class SSH(object): # pylint: disable=too-few-public-methods
raise ValueError('invalid port: {0}'.format(port))
self.__host = host
self.__port = nport
self.__ipvo = ()
def _resolve(self, ipvo):
# type: (Sequence[int]) -> Iterable[Tuple[int, Tuple[Any, ...]]]
@ -1612,7 +1875,9 @@ class SSH(object): # pylint: disable=too-few-public-methods
def connect(self, ipvo, timeout):
# type: (Sequence[int], float) -> None
err = None
for af, addr in self._resolve(ipvo):
if ipvo is not None:
self.__ipvo = ipvo
for af, addr in self._resolve(self.__ipvo):
s = None
try:
s = socket.socket(af, socket.SOCK_STREAM)
@ -1769,7 +2034,21 @@ class SSH(object): # pylint: disable=too-few-public-methods
pad_bytes = b'\x00' * padding
data = struct.pack('>Ib', plen, padding) + payload + pad_bytes
return self.send(data)
# Returns True if this Socket is connected, otherwise False.
def is_connected(self):
return (self.__sock is not None)
def close(self):
self.__cleanup()
self.reset()
self.__state = 0
self.__header = []
self.__banner = None
def reset(self):
super(SSH.Socket, self).reset()
def _close_socket(self, s):
# type: (Optional[socket.socket]) -> None
try:
@ -1786,27 +2065,185 @@ class SSH(object): # pylint: disable=too-few-public-methods
def __cleanup(self):
# type: () -> None
self._close_socket(self.__sock)
self.__sock = None
class KexDH(object): # pragma: nocover
def __init__(self, alg, g, p):
def __init__(self, kex_name, hash_alg, g, p):
# type: (str, int, int) -> None
self.__alg = alg
self.__kex_name = kex_name
self.__hash_alg = hash_alg
self.__g = 0
self.__p = 0
self.__q = 0
self.__x = 0
self.__e = 0
self.set_params(g, p)
self.__ed25519_pubkey = 0
self.__hostkey_type = None
self.__hostkey_e = 0
self.__hostkey_n = 0
self.__hostkey_n_len = 0 # Length of the host key modulus.
self.__ca_n_len = 0 # Length of the CA key modulus (if hostkey is a cert).
self.__f = 0
self.__h_sig = 0
def set_params(self, g, p):
self.__g = g
self.__p = p
self.__q = (self.__p - 1) // 2
self.__x = 0
self.__e = 0
def send_init(self, s):
def send_init(self, s, init_msg=SSH.Protocol.MSG_KEXDH_INIT):
# type: (SSH.Socket) -> None
r = random.SystemRandom()
self.__x = r.randrange(2, self.__q)
self.__e = pow(self.__g, self.__x, self.__p)
s.write_byte(SSH.Protocol.MSG_KEXDH_INIT)
s.write_byte(init_msg)
s.write_mpint2(self.__e)
s.send_packet()
# Parse a KEXDH_REPLY or KEXDH_GEX_REPLY message from the server. This
# Contains the host key, among other things.
def recv_reply(self, s):
packet_type, payload = s.read_packet(2)
if packet_type != -1 and packet_type not in [SSH.Protocol.MSG_KEXDH_REPLY, SSH.Protocol.MSG_KEXDH_GEX_REPLY]:
# TODO: change Exception to something more specific.
raise Exception('Expected MSG_KEXDH_REPLY (%d) or MSG_KEXDH_GEX_REPLY (%d), but got %d instead.' % (SSH.Protocol.MSG_KEXDH_REPLY, SSH.Protocol.MSG_KEXDH_GEX_REPLY, packet_type))
elif packet_type == -1:
# A connection error occurred. We can't parse anything, so just
# return. The host key modulus (and perhaps certificate modulus)
# will remain at length 0.
return
hostkey_len = f_len = h_sig_len = 0 # pylint: disable=unused-variable
hostkey_type_len = hostkey_e_len = 0 # pylint: disable=unused-variable
key_id_len = principles_len = 0 # pylint: disable=unused-variable
critical_options_len = extensions_len = 0 # pylint: disable=unused-variable
nonce_len = ca_key_len = ca_key_type_len = 0 # pylint: disable=unused-variable
ca_key_len = ca_key_type_len = ca_key_e_len = 0 # pylint: disable=unused-variable
key_id = principles = None # pylint: disable=unused-variable
critical_options = extensions = None # pylint: disable=unused-variable
valid_after = valid_before = None # pylint: disable=unused-variable
nonce = ca_key = ca_key_type = None # pylint: disable=unused-variable
ca_key_e = ca_key_n = None # pylint: disable=unused-variable
# Get the host key blob, F, and signature.
ptr = 0
hostkey, hostkey_len, ptr = KexDH.__get_bytes(payload, ptr)
self.__f, f_len, ptr = KexDH.__get_bytes(payload, ptr)
self.__h_sig, h_sig_len, ptr = KexDH.__get_bytes(payload, ptr)
# Now pick apart the host key blob.
# Get the host key type (i.e.: 'ssh-rsa', 'ssh-ed25519', etc).
ptr = 0
self.__hostkey_type, hostkey_type_len, ptr = KexDH.__get_bytes(hostkey, ptr)
# If this is an RSA certificate, skip over the nonce.
if self.__hostkey_type.startswith(b'ssh-rsa-cert-v0'):
nonce, nonce_len, ptr = KexDH.__get_bytes(hostkey, ptr)
# The public key exponent.
hostkey_e, hostkey_e_len, ptr = KexDH.__get_bytes(hostkey, ptr)
self.__hostkey_e = int(binascii.hexlify(hostkey_e), 16)
# Here is the modulus size & actual modulus of the host key public key.
hostkey_n, self.__hostkey_n_len, ptr = KexDH.__get_bytes(hostkey, ptr)
self.__hostkey_n = int(binascii.hexlify(hostkey_n), 16)
# If this is an RSA certificate, continue parsing to extract the CA
# key.
if self.__hostkey_type.startswith(b'ssh-rsa-cert-v0'):
# Skip over the serial number.
ptr += 8
# Get the certificate type.
cert_type = int(binascii.hexlify(hostkey[ptr:ptr + 4]), 16)
ptr += 4
# Only SSH2_CERT_TYPE_HOST (2) makes sense in this context.
if cert_type == 2:
# Skip the key ID (this is the serial number of the
# certificate).
key_id, key_id_len, ptr = KexDH.__get_bytes(hostkey, ptr)
# The principles, which are... I don't know what.
principles, principles_len, ptr = KexDH.__get_bytes(hostkey, ptr)
# The timestamp that this certificate is valid after.
valid_after = hostkey[ptr:ptr + 8]
ptr += 8
# The timestamp that this certificate is valid before.
valid_before = hostkey[ptr:ptr + 8]
ptr += 8
# TODO: validate the principles, and time range.
# The critical options.
critical_options, critical_options_len, ptr = KexDH.__get_bytes(hostkey, ptr)
# Certificate extensions.
extensions, extensions_len, ptr = KexDH.__get_bytes(hostkey, ptr)
# Another nonce.
nonce, nonce_len, ptr = KexDH.__get_bytes(hostkey, ptr)
# Finally, we get to the CA key.
ca_key, ca_key_len, ptr = KexDH.__get_bytes(hostkey, ptr)
# Last in the host key blob is the CA signature. It isn't
# interesting to us, so we won't bother parsing any further.
# The CA key has the modulus, however...
ptr = 0
# 'ssh-rsa', 'rsa-sha2-256', etc.
ca_key_type, ca_key_type_len, ptr = KexDH.__get_bytes(ca_key, ptr)
# CA's public key exponent.
ca_key_e, ca_key_e_len, ptr = KexDH.__get_bytes(ca_key, ptr)
# CA's modulus. Bingo.
ca_key_n, self.__ca_n_len, ptr = KexDH.__get_bytes(ca_key, ptr)
@staticmethod
def __get_bytes(buf, ptr):
num_bytes = struct.unpack('>I', buf[ptr:ptr + 4])[0]
ptr += 4
return buf[ptr:ptr + num_bytes], num_bytes, ptr + num_bytes
# Converts a modulus length in bytes to its size in bits, after some
# possible adjustments.
@staticmethod
def __adjust_key_size(size):
size = size * 8
# Actual keys are observed to be about 8 bits bigger than expected
# (i.e.: 1024-bit keys have a 1032-bit modulus). Check if this is
# the case, and subtract 8 if so. This simply improves readability
# in the UI.
if (size >> 3) % 2 != 0:
size = size - 8
return size
# Returns the size of the hostkey, in bits.
def get_hostkey_size(self):
return KexDH.__adjust_key_size(self.__hostkey_n_len)
# Returns the size of the CA key, in bits.
def get_ca_size(self):
return KexDH.__adjust_key_size(self.__ca_n_len)
# Returns the size of the DH modulus, in bits.
def get_dh_modulus_size(self):
# -2 to account for the '0b' prefix in the string.
return len(bin(self.__p)) - 2
class KexGroup1(KexDH): # pragma: nocover
def __init__(self):
@ -1817,11 +2254,11 @@ class KexGroup1(KexDH): # pragma: nocover
'f25f14374fe1356d6d51c245e485b576625e7ec6f44c42e9a637ed6b0bff'
'5cb6f406b7edee386bfb5a899fa5ae9f24117c4b1fe649286651ece65381'
'ffffffffffffffff', 16)
super(KexGroup1, self).__init__('sha1', 2, p)
super(KexGroup1, self).__init__('KexGroup1', 'sha1', 2, p)
class KexGroup14(KexDH): # pragma: nocover
def __init__(self):
def __init__(self, hash_alg):
# type: () -> None
# rfc3526: 2048-bit modp group
p = int('ffffffffffffffffc90fdaa22168c234c4c6628b80dc1cd129024e088a67'
@ -1833,26 +2270,221 @@ class KexGroup14(KexDH): # pragma: nocover
'ca18217c32905e462e36ce3be39e772c180e86039b2783a2ec07a28fb5c5'
'5df06f4c52c9de2bcbf6955817183995497cea956ae515d2261898fa0510'
'15728e5a8aacaa68ffffffffffffffff', 16)
super(KexGroup14, self).__init__('sha1', 2, p)
super(KexGroup14, self).__init__('KexGroup14', hash_alg, 2, p)
def output_algorithms(title, alg_db, alg_type, algorithms, maxlen=0):
class KexGroup14_SHA1(KexGroup14):
def __init__(self):
super(KexGroup14_SHA1, self).__init__('sha1')
class KexGroup14_SHA256(KexGroup14):
def __init__(self):
super(KexGroup14_SHA256, self).__init__('sha256')
class KexGroup16_SHA512(KexDH):
def __init__(self):
# rfc3526: 4096-bit modp group
p = int('ffffffffffffffffc90fdaa22168c234c4c6628b80dc1cd129024e088a67'
'cc74020bbea63b139b22514a08798e3404ddef9519b3cd3a431b302b0a6d'
'f25f14374fe1356d6d51c245e485b576625e7ec6f44c42e9a637ed6b0bff'
'5cb6f406b7edee386bfb5a899fa5ae9f24117c4b1fe649286651ece45b3d'
'c2007cb8a163bf0598da48361c55d39a69163fa8fd24cf5f83655d23dca3'
'ad961c62f356208552bb9ed529077096966d670c354e4abc9804f1746c08'
'ca18217c32905e462e36ce3be39e772c180e86039b2783a2ec07a28fb5c5'
'5df06f4c52c9de2bcbf6955817183995497cea956ae515d2261898fa0510'
'15728e5a8aaac42dad33170d04507a33a85521abdf1cba64ecfb850458db'
'ef0a8aea71575d060c7db3970f85a6e1e4c7abf5ae8cdb0933d71e8c94e0'
'4a25619dcee3d2261ad2ee6bf12ffa06d98a0864d87602733ec86a64521f'
'2b18177b200cbbe117577a615d6c770988c0bad946e208e24fa074e5ab31'
'43db5bfce0fd108e4b82d120a92108011a723c12a787e6d788719a10bdba'
'5b2699c327186af4e23c1a946834b6150bda2583e9ca2ad44ce8dbbbc2db'
'04de8ef92e8efc141fbecaa6287c59474e6bc05d99b2964fa090c3a2233b'
'a186515be7ed1f612970cee2d7afb81bdd762170481cd0069127d5b05aa9'
'93b4ea988d8fddc186ffb7dc90a6c08f4df435c934063199ffffffffffff'
'ffff', 16)
super(KexGroup16_SHA512, self).__init__('KexGroup16_SHA512', 'sha512', 2, p)
class KexGroup18_SHA512(KexDH):
def __init__(self):
# rfc3526: 8192-bit modp group
p = int('ffffffffffffffffc90fdaa22168c234c4c6628b80dc1cd129024e088a67'
'cc74020bbea63b139b22514a08798e3404ddef9519b3cd3a431b302b0a6d'
'f25f14374fe1356d6d51c245e485b576625e7ec6f44c42e9a637ed6b0bff'
'5cb6f406b7edee386bfb5a899fa5ae9f24117c4b1fe649286651ece45b3d'
'c2007cb8a163bf0598da48361c55d39a69163fa8fd24cf5f83655d23dca3'
'ad961c62f356208552bb9ed529077096966d670c354e4abc9804f1746c08'
'ca18217c32905e462e36ce3be39e772c180e86039b2783a2ec07a28fb5c5'
'5df06f4c52c9de2bcbf6955817183995497cea956ae515d2261898fa0510'
'15728e5a8aaac42dad33170d04507a33a85521abdf1cba64ecfb850458db'
'ef0a8aea71575d060c7db3970f85a6e1e4c7abf5ae8cdb0933d71e8c94e0'
'4a25619dcee3d2261ad2ee6bf12ffa06d98a0864d87602733ec86a64521f'
'2b18177b200cbbe117577a615d6c770988c0bad946e208e24fa074e5ab31'
'43db5bfce0fd108e4b82d120a92108011a723c12a787e6d788719a10bdba'
'5b2699c327186af4e23c1a946834b6150bda2583e9ca2ad44ce8dbbbc2db'
'04de8ef92e8efc141fbecaa6287c59474e6bc05d99b2964fa090c3a2233b'
'a186515be7ed1f612970cee2d7afb81bdd762170481cd0069127d5b05aa9'
'93b4ea988d8fddc186ffb7dc90a6c08f4df435c93402849236c3fab4d27c'
'7026c1d4dcb2602646dec9751e763dba37bdf8ff9406ad9e530ee5db382f'
'413001aeb06a53ed9027d831179727b0865a8918da3edbebcf9b14ed44ce'
'6cbaced4bb1bdb7f1447e6cc254b332051512bd7af426fb8f401378cd2bf'
'5983ca01c64b92ecf032ea15d1721d03f482d7ce6e74fef6d55e702f4698'
'0c82b5a84031900b1c9e59e7c97fbec7e8f323a97a7e36cc88be0f1d45b7'
'ff585ac54bd407b22b4154aacc8f6d7ebf48e1d814cc5ed20f8037e0a797'
'15eef29be32806a1d58bb7c5da76f550aa3d8a1fbff0eb19ccb1a313d55c'
'da56c9ec2ef29632387fe8d76e3c0468043e8f663f4860ee12bf2d5b0b74'
'74d6e694f91e6dbe115974a3926f12fee5e438777cb6a932df8cd8bec4d0'
'73b931ba3bc832b68d9dd300741fa7bf8afc47ed2576f6936ba424663aab'
'639c5ae4f5683423b4742bf1c978238f16cbe39d652de3fdb8befc848ad9'
'22222e04a4037c0713eb57a81a23f0c73473fc646cea306b4bcbc8862f83'
'85ddfa9d4b7fa2c087e879683303ed5bdd3a062b3cf5b3a278a66d2a13f8'
'3f44f82ddf310ee074ab6a364597e899a0255dc164f31cc50846851df9ab'
'48195ded7ea1b1d510bd7ee74d73faf36bc31ecfa268359046f4eb879f92'
'4009438b481c6cd7889a002ed5ee382bc9190da6fc026e479558e4475677'
'e9aa9e3050e2765694dfc81f56e880b96e7160c980dd98edd3dfffffffff'
'ffffffff', 16)
super(KexGroup18_SHA512, self).__init__('KexGroup18_SHA512', 'sha512', 2, p)
class KexCurve25519_SHA256(KexDH):
def __init__(self):
super(KexCurve25519_SHA256, self).__init__('KexCurve25519_SHA256', 'sha256', 0, 0)
# To start an ED25519 kex, we simply send a random 256-bit number as the
# public key.
def send_init(self, s, init_msg=SSH.Protocol.MSG_KEXDH_INIT):
self.__ed25519_pubkey = os.urandom(32)
s.write_byte(init_msg)
s.write_string(self.__ed25519_pubkey)
s.send_packet()
class KexNISTP256(KexDH):
def __init__(self):
super(KexNISTP256, self).__init__('KexNISTP256', 'sha256', 0, 0)
# Because the server checks that the value sent here is valid (i.e.: it lies
# on the curve, among other things), we would have to write a lot of code
# or import an elliptic curve library in order to randomly generate a
# valid elliptic point each time. Hence, we will simply send a static
# value, which is enough for us to extract the server's host key.
def send_init(self, s, init_msg=SSH.Protocol.MSG_KEXDH_INIT):
s.write_byte(init_msg)
s.write_string(b'\x04\x0b\x60\x44\x9f\x8a\x11\x9e\xc7\x81\x0c\xa9\x98\xfc\xb7\x90\xaa\x6b\x26\x8c\x12\x4a\xc0\x09\xbb\xdf\xc4\x2c\x4c\x2c\x99\xb6\xe1\x71\xa0\xd4\xb3\x62\x47\x74\xb3\x39\x0c\xf2\x88\x4a\x84\x6b\x3b\x15\x77\xa5\x77\xd2\xa9\xc9\x94\xf9\xd5\x66\x19\xcd\x02\x34\xd1')
s.send_packet()
class KexNISTP384(KexDH):
def __init__(self):
super(KexNISTP384, self).__init__('KexNISTP384', 'sha256', 0, 0)
# See comment for KexNISTP256.send_init().
def send_init(self, s, init_msg=SSH.Protocol.MSG_KEXDH_INIT):
s.write_byte(init_msg)
s.write_string(b'\x04\xe2\x9b\x84\xce\xa1\x39\x50\xfe\x1e\xa3\x18\x70\x1c\xe2\x7a\xe4\xb5\x6f\xdf\x93\x9f\xd4\xf4\x08\xcc\x9b\x02\x10\xa4\xca\x77\x9c\x2e\x51\x44\x1d\x50\x7a\x65\x4e\x7e\x2f\x10\x2d\x2d\x4a\x32\xc9\x8e\x18\x75\x90\x6c\x19\x10\xda\xcc\xa8\xe9\xf4\xc4\x3a\x53\x80\x35\xf4\x97\x9c\x04\x16\xf9\x5a\xdc\xcc\x05\x94\x29\xfa\xc4\xd6\x87\x4e\x13\x21\xdb\x3d\x12\xac\xbd\x20\x3b\x60\xff\xe6\x58\x42')
s.send_packet()
class KexNISTP521(KexDH):
def __init__(self):
super(KexNISTP521, self).__init__('KexNISTP521', 'sha256', 0, 0)
# See comment for KexNISTP256.send_init().
def send_init(self, s, init_msg=SSH.Protocol.MSG_KEXDH_INIT):
s.write_byte(init_msg)
s.write_string(b'\x04\x01\x02\x90\x29\xe9\x8f\xa8\x04\xaf\x1c\x00\xf9\xc6\x29\xc0\x39\x74\x8e\xea\x47\x7e\x7c\xf7\x15\x6e\x43\x3b\x59\x13\x53\x43\xb0\xae\x0b\xe7\xe6\x7c\x55\x73\x52\xa5\x2a\xc1\x42\xde\xfc\xf4\x1f\x8b\x5a\x8d\xfa\xcd\x0a\x65\x77\xa8\xce\x68\xd2\xc6\x26\xb5\x3f\xee\x4b\x01\x7b\xd2\x96\x23\x69\x53\xc7\x01\xe1\x0d\x39\xe9\x87\x49\x3b\xc8\xec\xda\x0c\xf9\xca\xad\x89\x42\x36\x6f\x93\x78\x78\x31\x55\x51\x09\x51\xc0\x96\xd7\xea\x61\xbf\xc2\x44\x08\x80\x43\xed\xc6\xbb\xfb\x94\xbd\xf8\xdf\x2b\xd8\x0b\x2e\x29\x1b\x8c\xc4\x8a\x04\x2d\x3a')
s.send_packet()
class KexGroupExchange(KexDH):
def __init__(self, classname, hash_alg):
super(KexGroupExchange, self).__init__(classname, hash_alg, 0, 0)
def send_init(self, s, init_msg=SSH.Protocol.MSG_KEXDH_GEX_REQUEST):
self.send_init_gex(s)
# The group exchange starts with sending a message to the server with
# the minimum, maximum, and preferred number of bits are for the DH group.
# The server responds with a generator and prime modulus that matches that,
# then the handshake continues on like a normal DH handshake (except the
# SSH message types differ).
def send_init_gex(self, s, minbits=1024, prefbits=2048, maxbits=8192):
# Send the initial group exchange request. Tell the server what range
# of modulus sizes we will accept, along with our preference.
s.write_byte(SSH.Protocol.MSG_KEXDH_GEX_REQUEST)
s.write_int(minbits)
s.write_int(prefbits)
s.write_int(maxbits)
s.send_packet()
packet_type, payload = s.read_packet(2)
if packet_type != SSH.Protocol.MSG_KEXDH_GEX_GROUP:
# TODO: replace with a better exception type.
raise Exception('Expected MSG_KEXDH_GEX_REPLY (%d), but got %d instead.' % (SSH.Protocol.MSG_KEXDH_GEX_REPLY, packet_type))
# Parse the modulus (p) and generator (g) values from the server.
ptr = 0
p_len = struct.unpack('>I', payload[ptr:ptr + 4])[0]
ptr += 4
p = int(binascii.hexlify(payload[ptr:ptr + p_len]), 16)
ptr += p_len
g_len = struct.unpack('>I', payload[ptr:ptr + 4])[0]
ptr += 4
g = int(binascii.hexlify(payload[ptr:ptr + g_len]), 16)
ptr += g_len
# Now that we got the generator and modulus, perform the DH exchange
# like usual.
super(KexGroupExchange, self).set_params(g, p)
super(KexGroupExchange, self).send_init(s, SSH.Protocol.MSG_KEXDH_GEX_INIT)
class KexGroupExchange_SHA1(KexGroupExchange):
def __init__(self):
super(KexGroupExchange_SHA1, self).__init__('KexGroupExchange_SHA1', 'sha1')
class KexGroupExchange_SHA256(KexGroupExchange):
def __init__(self):
super(KexGroupExchange_SHA256, self).__init__('KexGroupExchange_SHA256', 'sha256')
def output_algorithms(title, alg_db, alg_type, algorithms, maxlen=0, alg_sizes=None):
# type: (str, Dict[str, Dict[str, List[List[Optional[str]]]]], str, List[text_type], int) -> None
with OutputBuffer() as obuf:
for algorithm in algorithms:
output_algorithm(alg_db, alg_type, algorithm, maxlen)
output_algorithm(alg_db, alg_type, algorithm, maxlen, alg_sizes)
if len(obuf) > 0:
out.head('# ' + title)
obuf.flush()
out.sep()
def output_algorithm(alg_db, alg_type, alg_name, alg_max_len=0):
def output_algorithm(alg_db, alg_type, alg_name, alg_max_len=0, alg_sizes=None):
# type: (Dict[str, Dict[str, List[List[Optional[str]]]]], str, text_type, int) -> None
prefix = '(' + alg_type + ') '
if alg_max_len == 0:
alg_max_len = len(alg_name)
padding = '' if out.batch else ' ' * (alg_max_len - len(alg_name))
# If this is an RSA host key or DH GEX, append the size to its name and fix
# the padding.
alg_name_with_size = None
if (alg_sizes is not None) and (alg_name in alg_sizes):
hostkey_size, ca_size = alg_sizes[alg_name]
if ca_size > 0:
alg_name_with_size = '%s (%d-bit cert/%d-bit CA)' % (alg_name, hostkey_size, ca_size)
padding = padding[0:-15]
else:
alg_name_with_size = '%s (%d-bit)' % (alg_name, hostkey_size)
padding = padding[0:-11]
texts = []
if len(alg_name.strip()) == 0:
return
@ -1876,6 +2508,8 @@ def output_algorithm(alg_db, alg_type, alg_name, alg_max_len=0):
texts.append(('info', ''))
else:
texts.append(('warn', 'unknown algorithm'))
alg_name = alg_name_with_size if alg_name_with_size is not None else alg_name
first = True
for level, text in texts:
f = getattr(out, level)
@ -1987,20 +2621,24 @@ def output_recommendations(algs, software, padlen=0):
for alg_type in ['kex', 'key', 'enc', 'mac']:
if alg_type not in alg_rec[sshv]:
continue
for action in ['del', 'add']:
for action in ['del', 'add', 'chg']:
if action not in alg_rec[sshv][alg_type]:
continue
for name in alg_rec[sshv][alg_type][action]:
p = '' if out.batch else ' ' * (padlen - len(name))
chg_additional_info = ''
if action == 'del':
an, sg, fn = 'remove', '-', out.warn
if alg_rec[sshv][alg_type][action][name] >= 10:
fn = out.fail
else:
elif action == 'add':
an, sg, fn = 'append', '+', out.good
elif action == 'chg':
an, sg, fn = 'change', '!', out.fail
chg_additional_info = ' (increase modulus size to 2048 bits or larger)'
b = '(SSH{0})'.format(sshv) if sshv == 1 else ''
fm = '(rec) {0}{1}{2}-- {3} algorithm to {4} {5}'
fn(fm.format(sg, name, p, alg_type, an, b))
fm = '(rec) {0}{1}{2}-- {3} algorithm to {4}{5} {6}'
fn(fm.format(sg, name, p, alg_type, an, chg_additional_info, b))
if len(obuf) > 0:
if software is not None:
title = '(for {0})'.format(software.display(False))
@ -2057,9 +2695,9 @@ def output(banner, header, kex=None, pkm=None):
if kex is not None:
adb = SSH2.KexDB.ALGORITHMS
title, atype = 'key exchange algorithms', 'kex'
output_algorithms(title, adb, atype, kex.kex_algorithms, maxlen)
output_algorithms(title, adb, atype, kex.kex_algorithms, maxlen, kex.dh_modulus_sizes())
title, atype = 'host-key algorithms', 'key'
output_algorithms(title, adb, atype, kex.key_algorithms, maxlen)
output_algorithms(title, adb, atype, kex.key_algorithms, maxlen, kex.rsa_key_sizes())
title, atype = 'encryption algorithms (ciphers)', 'enc'
output_algorithms(title, adb, atype, kex.server.encryption, maxlen)
title, atype = 'message authentication code algorithms', 'mac'
@ -2242,6 +2880,8 @@ def audit(aconf, sshv=None):
output(banner, header, pkm=pkm)
elif sshv == 2:
kex = SSH2.Kex.parse(payload)
SSH2.RSAKeyTest.run(s, kex)
SSH2.GEXTest.run(s, kex)
output(banner, header, kex=kex)