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5af8859d6b
ssh-audit/ssh-audit.py
Andris Raugulis 5af8859d6b Add initial code for Diffie-Hellman key exchange.
2016-04-01 18:37:20 +03:00

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#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""
The MIT License (MIT)
Copyright (C) 2015 Andris Raugulis (moo@arthepsy.eu)
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
"""
from __future__ import print_function
import os, io, sys, socket, struct, random
SSH_BANNER = 'SSH-2.0-OpenSSH_7.2'
def usage():
p = os.path.basename(sys.argv[0])
out.head('# {0} v1.0.20160207, moo@arthepsy.eu'.format(p))
out.info('\nusage: {} [-nv] host[:port]\n'.format(p))
out.info(' -v verbose')
out.info(' -n disable colors' + os.linesep)
sys.exit(1)
class Output(object):
colors = True
verbose = False
_colors = {
'head': 36,
'good': 32,
'fail': 31,
'warn': 33,
}
def sep(self):
print()
def _colorized(self, color):
return lambda x: print(color + x + '\033[0m')
def __getattr__(self, name):
if self.colors and os.name == 'posix' and name in self._colors:
color = '\033[0;{0}m'.format(self._colors[name])
return self._colorized(color)
else:
return lambda x: print(x)
class KexParty(object):
encryption = []
mac = []
compression = []
languages = []
class Kex(object):
cookie = None
kex_algorithms = []
key_algorithms = []
server = KexParty()
client = KexParty()
follows = False
unused = 0
@classmethod
def parse(cls, payload):
kex = cls()
buf = ReadBuf(payload)
kex.cookie = buf.read(16)
kex.kex_algorithms = buf.read_list()
kex.key_algorithms = buf.read_list()
kex.client.encryption = buf.read_list()
kex.server.encryption = buf.read_list()
kex.client.mac = buf.read_list()
kex.server.mac = buf.read_list()
kex.client.compression = buf.read_list()
kex.server.compression = buf.read_list()
kex.client.languages = buf.read_list()
kex.server.languages = buf.read_list()
kex.follows = buf.read_bool()
kex.unused = buf.read_int()
return kex
class ReadBuf(object):
def __init__(self, data = None):
super(ReadBuf, self).__init__()
self._buf = io.BytesIO(data) if data else io.BytesIO()
self._len = len(data) if data else 0
@property
def unread_len(self):
return self._len - self._buf.tell()
def read(self, size):
return self._buf.read(size)
def read_line(self):
return self._buf.readline().rstrip().decode('utf-8')
def read_int(self):
return struct.unpack('>I', self.read(4))[0]
def read_bool(self):
return struct.unpack('b', self.read(1))[0] != 0
def read_list(self):
list_size = self.read_int()
return self.read(list_size).decode().split(',')
class WriteBuf(object):
def __init__(self, data = None):
super(WriteBuf, self).__init__()
self._wbuf = io.BytesIO(data) if data else io.BytesIO()
def write(self, data):
self._wbuf.write(data)
def write_byte(self, v):
self.write(struct.pack('>B', v))
def write_bool(self, v):
self.write_byte(1 if v else 0)
def write_int(self, v):
self.write(struct.pack('>I', v))
def write_string(self, v):
if not isinstance(v, bytes):
v = bytes(bytearray(v, 'utf-8'))
n = len(v)
self.write(struct.pack('>I', n))
self.write(v)
def write_list(self, v):
self.write_string(','.join(v))
def write_mpint(self, v):
length = v.bit_length() // 8 + 1
data = [(v >> i*8) & 0xff for i in reversed(range(length))]
data = bytes(bytearray(data))
self.write_string(data)
class SSH(object):
MSG_KEXINIT = 20
MSG_NEWKEYS = 21
MSG_KEXDH_INIT = 30
MSG_KEXDH_REPLY = 32
class Socket(ReadBuf, WriteBuf):
SM_BANNER_SENT = 1
def __init__(self, host, port, cto = 3.0, rto = 5.0):
self.__block_size = 8
self.__state = 0
self.__banner = None
super(SSH.Socket, self).__init__()
try:
self.__sock = socket.create_connection((host, port), cto)
self.__sock.settimeout(rto)
except Exception as e:
out.fail('[fail] {}'.format(e))
sys.exit(1)
def __enter__(self):
return self
def get_banner(self):
if self.__state < self.SM_BANNER_SENT:
self.send_banner()
if self.__banner is None:
self.recv()
self.__banner = self.read_line()
return self.__banner
def recv(self, size = 2048):
data = self.__sock.recv(size)
pos = self._buf.tell()
self._buf.seek(0, 2)
self._buf.write(data)
self._len += len(data)
self._buf.seek(pos, 0)
def send(self, data):
self.__sock.send(data)
def send_banner(self, banner = SSH_BANNER):
self.send(banner.encode() + b'\r\n')
if self.__state < self.SM_BANNER_SENT:
self.__state = self.SM_BANNER_SENT
def read_packet(self):
if self.unread_len < self.__block_size:
self.recv()
header = self.read(self.__block_size)
packet_size = struct.unpack('>I', header[:4])[0]
rest = header[4:]
lrest = len(rest)
padding = ord(rest[0:1])
packet_type = ord(rest[1:2])
if (packet_size - lrest) % self.__block_size != 0:
out.fail('[exception] invalid ssh packet (block size)')
sys.exit(1)
rlen = packet_size - lrest
if self.unread_len < rlen:
self.recv()
buf = self.read(rlen)
packet = rest[2:] + buf[0:packet_size - lrest]
payload = packet[0:packet_size - padding]
return packet_type, payload
def send_packet(self):
payload = self._wbuf.getvalue()
self._wbuf.truncate(0)
self._wbuf.seek(0)
padding = -(len(payload) + 5) % 8
if padding < 4:
padding += 8
plen = len(payload) + padding + 1
pad_bytes = b'\x00' * padding
data = struct.pack('>Ib', plen, padding) + payload + pad_bytes
self.send(data)
def __del__(self):
self.__cleanup()
def __exit__(self, ex_type, ex_value, tb):
self.__cleanup()
def __cleanup(self):
try:
self.__sock.shutdown(socket.SHUT_RDWR)
self.__sock.close()
except:
pass
class KexDH(object):
def __init__(self, alg, g, p):
self.__alg = alg
self.__g = g
self.__p = p
self.__q = (self.__p - 1) // 2
self.__x = None
def send_init(self, s):
r = random.SystemRandom()
self.__x = r.randrange(2, self.__q)
self.__e = pow(self.__g, self.__x, self.__p)
s.write_byte(SSH.MSG_KEXDH_INIT)
s.write_mpint(self.__e)
s.send_packet()
class KexGroup1(KexDH):
def __init__(self):
# rfc2409: second oakley group
p = int('ffffffffffffffffc90fdaa22168c234c4c6628b80dc1cd129024e088a67'
'cc74020bbea63b139b22514a08798e3404ddef9519b3cd3a431b302b0a6d'
'f25f14374fe1356d6d51c245e485b576625e7ec6f44c42e9a637ed6b0bff'
'5cb6f406b7edee386bfb5a899fa5ae9f24117c4b1fe649286651ece65381'
'ffffffffffffffff', 16)
super(KexGroup1, self).__init__('sha1', 2, p)
class KexGroup14(KexDH):
def __init__(self):
# rfc3526: 2048-bit modp group
p = int('ffffffffffffffffc90fdaa22168c234c4c6628b80dc1cd129024e088a67'
'cc74020bbea63b139b22514a08798e3404ddef9519b3cd3a431b302b0a6d'
'f25f14374fe1356d6d51c245e485b576625e7ec6f44c42e9a637ed6b0bff'
'5cb6f406b7edee386bfb5a899fa5ae9f24117c4b1fe649286651ece45b3d'
'c2007cb8a163bf0598da48361c55d39a69163fa8fd24cf5f83655d23dca3'
'ad961c62f356208552bb9ed529077096966d670c354e4abc9804f1746c08'
'ca18217c32905e462e36ce3be39e772c180e86039b2783a2ec07a28fb5c5'
'5df06f4c52c9de2bcbf6955817183995497cea956ae515d2261898fa0510'
'15728e5a8aacaa68ffffffffffffffff', 16)
super(KexGroup14, self).__init__('sha1', 2, p)
def get_ssh_ver(versions):
tv = []
for v in versions.split(','):
if v.startswith('d'):
tv.append('Dropbear SSH {0}'.format(v[1:]))
else:
tv.append('OpenSSH {0}'.format(v))
return 'available since ' + ', '.join(tv).rstrip(', ')
WARN_OPENSSH72_LEGACY = 'disabled (in client) since OpenSSH 7.2, legacy algorithm'
FAIL_OPENSSH70_LEGACY = 'removed since OpenSSH 7.0, legacy algorithm'
FAIL_OPENSSH70_WEAK = 'removed (in server) and disabled (in client) since OpenSSH 7.0, weak algorithm'
FAIL_OPENSSH70_LOGJAM = 'disabled (in client) since OpenSSH 7.0, logjam attack'
INFO_OPENSSH69_CHACHA = 'default cipher since OpenSSH 6.9.'
FAIL_OPENSSH67_UNSAFE = 'removed (in server) since OpenSSH 6.7, unsafe algorithm'
FAIL_OPENSSH61_REMOVE = 'removed since OpenSSH 6.1, removed from specification'
FAIL_OPENSSH31_REMOVE = 'removed since OpenSSH 3.1'
FAIL_DBEAR67_DISABLED = 'disabled since Dropbear SSH 2015.67'
FAIL_DBEAR53_DISABLED = 'disabled since Dropbear SSH 0.53'
FAIL_PLAINTEXT = 'no encryption/integrity'
TEXT_CURVES_WEAK = 'using weak elliptic curves'
TEXT_RNDSIG_KEY = 'using weak random number generator could reveal the key'
TEXT_MODULUS_SIZE = 'using small 1024-bit modulus'
TEXT_MODULUS_CUSTOM = 'using custom size modulus (possibly weak)'
TEXT_HASH_WEAK = 'using weak hashing algorithm'
TEXT_CIPHER_MODE = 'using weak cipher mode'
TEXT_BLOCK_SIZE = 'using small 64-bit block size'
TEXT_CIPHER_WEAK = 'using weak cipher'
TEXT_ENCRYPT_AND_MAC = 'using encrypt-and-MAC mode'
TEXT_TAG_SIZE = 'using small 64-bit tag size'
KEX_DB = {
'kex': {
'diffie-hellman-group1-sha1': ['2.3.0,d0.28', [FAIL_OPENSSH67_UNSAFE, FAIL_OPENSSH70_LOGJAM], [TEXT_MODULUS_SIZE, TEXT_HASH_WEAK]],
'diffie-hellman-group14-sha1': ['3.9,d0.53', [], [TEXT_HASH_WEAK]],
'diffie-hellman-group-exchange-sha1': ['2.3.0', [FAIL_OPENSSH67_UNSAFE], [TEXT_HASH_WEAK]],
'diffie-hellman-group-exchange-sha256': ['4.4', [], [TEXT_MODULUS_CUSTOM]],
'ecdh-sha2-nistp256': ['5.7,d2013.62', [TEXT_CURVES_WEAK]],
'ecdh-sha2-nistp384': ['5.7,d2013.62', [TEXT_CURVES_WEAK]],
'ecdh-sha2-nistp521': ['5.7,d2013.62', [TEXT_CURVES_WEAK]],
'curve25519-sha256@libssh.org': ['6.5,d2013.62'],
'kexguess2@matt.ucc.asn.au': ['d2013.57'],
},
'key': {
'rsa-sha2-256': ['7.2'],
'rsa-sha2-512': ['7.2'],
'ssh-ed25519': ['6.5'],
'ssh-ed25519-cert-v01@openssh.com': ['6.5'],
'ssh-rsa': ['2.5.0,d0.28'],
'ssh-dss': ['2.1.0,d0.28', [FAIL_OPENSSH70_WEAK], [TEXT_MODULUS_SIZE, TEXT_RNDSIG_KEY]],
'ecdsa-sha2-nistp256': ['5.7,d2013.62', [TEXT_CURVES_WEAK], [TEXT_RNDSIG_KEY]],
'ecdsa-sha2-nistp384': ['5.7,d2013.62', [TEXT_CURVES_WEAK], [TEXT_RNDSIG_KEY]],
'ecdsa-sha2-nistp521': ['5.7,d2013.62', [TEXT_CURVES_WEAK], [TEXT_RNDSIG_KEY]],
'ssh-rsa-cert-v00@openssh.com': ['5.4', [FAIL_OPENSSH70_LEGACY], []],
'ssh-dss-cert-v00@openssh.com': ['5.4', [FAIL_OPENSSH70_LEGACY], [TEXT_MODULUS_SIZE, TEXT_RNDSIG_KEY]],
'ssh-rsa-cert-v01@openssh.com': ['5.6'],
'ssh-dss-cert-v01@openssh.com': ['5.6', [FAIL_OPENSSH70_WEAK], [TEXT_MODULUS_SIZE, TEXT_RNDSIG_KEY]],
'ecdsa-sha2-nistp256-cert-v01@openssh.com': ['5.7', [TEXT_CURVES_WEAK], [TEXT_RNDSIG_KEY]],
'ecdsa-sha2-nistp384-cert-v01@openssh.com': ['5.7', [TEXT_CURVES_WEAK], [TEXT_RNDSIG_KEY]],
'ecdsa-sha2-nistp521-cert-v01@openssh.com': ['5.7', [TEXT_CURVES_WEAK], [TEXT_RNDSIG_KEY]],
},
'enc': {
'none': ['1.2.2,d2013.56', [FAIL_PLAINTEXT]],
'3des-cbc': ['1.2.2,d0.28', [FAIL_OPENSSH67_UNSAFE], [TEXT_CIPHER_WEAK, TEXT_CIPHER_MODE, TEXT_BLOCK_SIZE]],
'3des-ctr': ['d0.52'],
'blowfish-cbc': ['1.2.2,d0.28', [FAIL_OPENSSH67_UNSAFE, FAIL_DBEAR53_DISABLED], [WARN_OPENSSH72_LEGACY, TEXT_CIPHER_MODE, TEXT_BLOCK_SIZE]],
'twofish-cbc': ['d0.28', [FAIL_DBEAR67_DISABLED], [TEXT_CIPHER_MODE]],
'twofish128-cbc': ['d0.47', [FAIL_DBEAR67_DISABLED], [TEXT_CIPHER_MODE]],
'twofish256-cbc': ['d0.47', [FAIL_DBEAR67_DISABLED], [TEXT_CIPHER_MODE]],
'twofish128-ctr': ['d2015.68'],
'twofish256-ctr': ['d2015.68'],
'cast128-cbc': ['2.1.0', [FAIL_OPENSSH67_UNSAFE], [WARN_OPENSSH72_LEGACY, TEXT_CIPHER_MODE, TEXT_BLOCK_SIZE]],
'arcfour': ['2.1.0', [FAIL_OPENSSH67_UNSAFE], [WARN_OPENSSH72_LEGACY, TEXT_CIPHER_WEAK]],
'arcfour128': ['4.2', [FAIL_OPENSSH67_UNSAFE], [WARN_OPENSSH72_LEGACY, TEXT_CIPHER_WEAK]],
'arcfour256': ['4.2', [FAIL_OPENSSH67_UNSAFE], [WARN_OPENSSH72_LEGACY, TEXT_CIPHER_WEAK]],
'aes128-cbc': ['2.3.0,d0.28', [FAIL_OPENSSH67_UNSAFE], [TEXT_CIPHER_MODE]],
'aes192-cbc': ['2.3.0', [FAIL_OPENSSH67_UNSAFE], [TEXT_CIPHER_MODE]],
'aes256-cbc': ['2.3.0,d0.47', [FAIL_OPENSSH67_UNSAFE], [TEXT_CIPHER_MODE]],
'rijndael128-cbc': ['2.3.0', [FAIL_OPENSSH31_REMOVE], [TEXT_CIPHER_MODE]],
'rijndael192-cbc': ['2.3.0', [FAIL_OPENSSH31_REMOVE], [TEXT_CIPHER_MODE]],
'rijndael256-cbc': ['2.3.0', [FAIL_OPENSSH31_REMOVE], [TEXT_CIPHER_MODE]],
'rijndael-cbc@lysator.liu.se': ['2.3.0', [FAIL_OPENSSH67_UNSAFE], [WARN_OPENSSH72_LEGACY, TEXT_CIPHER_MODE]],
'aes128-ctr': ['3.7,d0.52'],
'aes192-ctr': ['3.7'],
'aes256-ctr': ['3.7,d0.52'],
'aes128-gcm@openssh.com': ['6.2'],
'aes256-gcm@openssh.com': ['6.2'],
'chacha20-poly1305@openssh.com': ['6.5', [], [], [INFO_OPENSSH69_CHACHA]],
},
'mac': {
'none': ['d2013.56', [FAIL_PLAINTEXT]],
'hmac-sha1': ['2.1.0,d0.28', [], [TEXT_ENCRYPT_AND_MAC, TEXT_HASH_WEAK]],
'hmac-sha1-96': ['2.5.0,d0.47', [FAIL_OPENSSH67_UNSAFE], [WARN_OPENSSH72_LEGACY, TEXT_ENCRYPT_AND_MAC, TEXT_HASH_WEAK]],
'hmac-sha2-256': ['5.9,d2013.56', [], [TEXT_ENCRYPT_AND_MAC]],
'hmac-sha2-256-96': ['5.9', [FAIL_OPENSSH61_REMOVE], [TEXT_ENCRYPT_AND_MAC]],
'hmac-sha2-512': ['5.9,d2013.56', [], [TEXT_ENCRYPT_AND_MAC]],
'hmac-sha2-512-96': ['5.9', [FAIL_OPENSSH61_REMOVE], [TEXT_ENCRYPT_AND_MAC]],
'hmac-md5': ['2.1.0,d0.28', [FAIL_OPENSSH67_UNSAFE], [WARN_OPENSSH72_LEGACY, TEXT_ENCRYPT_AND_MAC, TEXT_HASH_WEAK]],
'hmac-md5-96': ['2.5.0', [FAIL_OPENSSH67_UNSAFE], [WARN_OPENSSH72_LEGACY, TEXT_ENCRYPT_AND_MAC, TEXT_HASH_WEAK]],
'hmac-ripemd160': ['2.5.0', [FAIL_OPENSSH67_UNSAFE], [WARN_OPENSSH72_LEGACY, TEXT_ENCRYPT_AND_MAC]],
'hmac-ripemd160@openssh.com': ['2.1.0', [FAIL_OPENSSH67_UNSAFE], [WARN_OPENSSH72_LEGACY, TEXT_ENCRYPT_AND_MAC]],
'umac-64@openssh.com': ['4.7', [], [TEXT_ENCRYPT_AND_MAC, TEXT_TAG_SIZE]],
'umac-128@openssh.com': ['6.2', [], [TEXT_ENCRYPT_AND_MAC]],
'hmac-sha1-etm@openssh.com': ['6.2', [], [WARN_OPENSSH72_LEGACY, TEXT_HASH_WEAK]],
'hmac-sha1-96-etm@openssh.com': ['6.2', [FAIL_OPENSSH67_UNSAFE], [TEXT_HASH_WEAK]],
'hmac-sha2-256-etm@openssh.com': ['6.2'],
'hmac-sha2-512-etm@openssh.com': ['6.2'],
'hmac-md5-etm@openssh.com': ['6.2', [FAIL_OPENSSH67_UNSAFE], [WARN_OPENSSH72_LEGACY, TEXT_HASH_WEAK]],
'hmac-md5-96-etm@openssh.com': ['6.2', [FAIL_OPENSSH67_UNSAFE], [WARN_OPENSSH72_LEGACY, TEXT_HASH_WEAK]],
'hmac-ripemd160-etm@openssh.com': ['6.2', [FAIL_OPENSSH67_UNSAFE], [WARN_OPENSSH72_LEGACY]],
'umac-64-etm@openssh.com': ['6.2', [], [TEXT_TAG_SIZE]],
'umac-128-etm@openssh.com': ['6.2'],
}
}
def process_algorithms(alg_type, algorithms, maxlen=0):
for algorithm in algorithms:
process_algorithm(alg_type, algorithm, maxlen)
def process_algorithm(alg_type, alg_name, alg_max_len=0):
prefix = '(' + alg_type + ') '
if alg_max_len == 0:
alg_max_len = len(alg_name)
padding = ' ' * (alg_max_len - len(alg_name))
texts = []
if alg_name in KEX_DB[alg_type]:
alg_desc = KEX_DB[alg_type][alg_name]
ldesc = len(alg_desc)
for idx, level in enumerate(['fail', 'warn', 'info']):
if level == 'info':
texts.append((level, get_ssh_ver(alg_desc[0])))
idx = idx + 1
if ldesc > idx:
for t in alg_desc[idx]:
texts.append((level, t))
if len(texts) == 0:
texts.append(('info', ''))
else:
texts.append(('warn', 'unknown algorithm'))
first = True
for (level, text) in texts:
f = getattr(out, level)
text = '[' + level + '] ' + text
if first:
if first and level == 'info':
f = out.good
f(prefix + alg_name + padding + ' -- ' + text)
first = False
else:
if out.verbose:
f(prefix + alg_name + padding + ' -- ' + text)
else:
f(' ' * len(prefix + alg_name) + padding + ' `- ' + text)
def process_kex(kex):
compressions = [x for x in kex.server.compression if x != 'none']
if len(compressions) > 0:
cmptxt = 'enabled ({0})'.format(', '.join(compressions))
else:
cmptxt = 'disabled'
out.good('[info] compression is ' + cmptxt)
ml = lambda l: max(len(i) for i in l)
maxlen = max(ml(kex.kex_algorithms),
ml(kex.key_algorithms),
ml(kex.server.encryption),
ml(kex.server.mac))
out.head('\n# key exchange algorithms')
process_algorithms('kex', kex.kex_algorithms, maxlen)
out.head('\n# host-key algorithms')
process_algorithms('key', kex.key_algorithms, maxlen)
out.head('\n# encryption algorithms (ciphers)')
process_algorithms('enc', kex.server.encryption, maxlen)
out.head('\n# message authentication code algorithms')
process_algorithms('mac', kex.server.mac, maxlen)
out.sep()
def parse_int(v):
try:
return int(v)
except:
return 0
def parse_args():
host = None
port = 22
for arg in sys.argv[1:]:
if arg.startswith('-'):
arg = arg.lstrip('-')
if arg == 'n': out.colors = False
elif arg == 'v': out.verbose = True
continue
s = arg.split(':')
host = s[0].strip()
if len(s) > 1:
port = parse_int(s[1])
if not host or port <= 0:
usage()
return host, port
def main():
host, port = parse_args()
s = SSH.Socket(host, port)
banner = s.get_banner()
out.head('# general')
out.good('[info] banner: ' + banner)
if banner.startswith('SSH-1.99-'):
out.fail('[fail] protocol SSH1 enabled')
packet_type, payload = s.read_packet()
if packet_type != SSH.MSG_KEXINIT:
out.fail('[exception] did not receive MSG_KEXINIT (20), instead received unknown message ({0})'.format(packet_type))
sys.exit(1)
kex = Kex.parse(payload)
process_kex(kex)
if __name__ == '__main__':
out = Output()
main()
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