"""
The MIT License (MIT)
Copyright (C) 2017-2021 Joe Testa (jtesta@positronsecurity.com)
Copyright (C) 2017 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.
"""
# pylint: disable=unused-import
from typing import Dict, List, Set, Sequence, Tuple, Iterable # noqa: F401
from typing import Callable, Optional, Union, Any # noqa: F401
from ssh_audit.algorithm import Algorithm
from ssh_audit.product import Product
from ssh_audit.software import Software
from ssh_audit.ssh1_kexdb import SSH1_KexDB
from ssh_audit.ssh1_publickeymessage import SSH1_PublicKeyMessage
from ssh_audit.ssh2_kex import SSH2_Kex
from ssh_audit.ssh2_kexdb import SSH2_KexDB
from ssh_audit.timeframe import Timeframe
from ssh_audit.utils import Utils
class Algorithms:
def __init__(self, pkm: Optional[SSH1_PublicKeyMessage], kex: Optional[SSH2_Kex]) -> None:
self.__ssh1kex = pkm
self.__ssh2kex = kex
@property
def ssh1kex(self) -> Optional[SSH1_PublicKeyMessage]:
return self.__ssh1kex
@property
def ssh2kex(self) -> Optional[SSH2_Kex]:
return self.__ssh2kex
@property
def ssh1(self) -> Optional['Algorithms.Item']:
if self.ssh1kex is None:
return None
item = Algorithms.Item(1, SSH1_KexDB.get_db())
item.add('key', ['ssh-rsa1'])
item.add('enc', self.ssh1kex.supported_ciphers)
item.add('aut', self.ssh1kex.supported_authentications)
return item
@property
def ssh2(self) -> Optional['Algorithms.Item']:
if self.ssh2kex is None:
return None
item = Algorithms.Item(2, SSH2_KexDB.get_db())
item.add('kex', self.ssh2kex.kex_algorithms)
item.add('key', self.ssh2kex.key_algorithms)
item.add('enc', self.ssh2kex.server.encryption)
item.add('mac', self.ssh2kex.server.mac)
return item
@property
def values(self) -> Iterable['Algorithms.Item']:
for item in [self.ssh1, self.ssh2]:
if item is not None:
yield item
@property
def maxlen(self) -> int:
def _ml(items: Sequence[str]) -> int:
return max(len(i) for i in items)
maxlen = 0
if self.ssh1kex is not None:
maxlen = max(_ml(self.ssh1kex.supported_ciphers),
_ml(self.ssh1kex.supported_authentications),
maxlen)
if self.ssh2kex is not None:
maxlen = max(_ml(self.ssh2kex.kex_algorithms),
_ml(self.ssh2kex.key_algorithms),
_ml(self.ssh2kex.server.encryption),
_ml(self.ssh2kex.server.mac),
maxlen)
return maxlen
def get_ssh_timeframe(self, for_server: Optional[bool] = None) -> 'Timeframe':
timeframe = Timeframe()
for alg_pair in self.values:
alg_db = alg_pair.db
for alg_type, alg_list in alg_pair.items():
for alg_name in alg_list:
alg_name_native = Utils.to_text(alg_name)
alg_desc = alg_db[alg_type].get(alg_name_native)
if alg_desc is None:
continue
versions = alg_desc[0]
timeframe.update(versions, for_server)
return timeframe
def get_recommendations(self, software: Optional['Software'], for_server: bool = True) -> Tuple[Optional['Software'], Dict[int, Dict[str, Dict[str, Dict[str, int]]]]]:
# pylint: disable=too-many-locals,too-many-statements
vproducts = [Product.OpenSSH,
Product.DropbearSSH,
Product.LibSSH,
Product.TinySSH]
# Set to True if server is not one of vproducts, above.
unknown_software = False
if software is not None:
if software.product not in vproducts:
unknown_software = True
# The code below is commented out because it would try to guess what the server is,
# usually resulting in wild & incorrect recommendations.
# if software is None:
# ssh_timeframe = self.get_ssh_timeframe(for_server)
# for product in vproducts:
# if product not in ssh_timeframe:
# continue
# version = ssh_timeframe.get_from(product, for_server)
# if version is not None:
# software = SSH.Software(None, product, version, None, None)
# break
rec: Dict[int, Dict[str, Dict[str, Dict[str, int]]]] = {}
if software is None:
unknown_software = True
for alg_pair in self.values:
sshv, alg_db = alg_pair.sshv, alg_pair.db
rec[sshv] = {}
for alg_type, alg_list in alg_pair.items():
if alg_type == 'aut':
continue
rec[sshv][alg_type] = {'add': {}, 'del': {}, 'chg': {}}
for n, alg_desc in alg_db[alg_type].items():
versions = alg_desc[0]
empty_version = False
if len(versions) == 0 or versions[0] is None:
empty_version = True
else:
matches = False
if unknown_software:
matches = True
for v in versions[0].split(','):
ssh_prefix, ssh_version, is_cli = Algorithm.get_ssh_version(v)
if not ssh_version:
continue
if (software is not None) and (ssh_prefix != software.product):
continue
if is_cli and for_server:
continue
if (software is not None) and (software.compare_version(ssh_version) < 0):
continue
matches = True
break
if not matches:
continue
adl, faults = len(alg_desc), 0
for i in range(1, 3):
if not adl > i:
continue
fc = len(alg_desc[i])
if fc > 0:
faults += pow(10, 2 - i) * fc
if n not in alg_list:
# Don't recommend certificate or token types; these will only appear in the server's list if they are fully configured & functional on the server. Also don't recommend 'ext-info-[cs]' nor 'kex-strict-[cs]-v00@openssh.com' key exchanges.
if faults > 0 or \
(alg_type == 'key' and (('-cert-' in n) or (n.startswith('sk-')))) or \
(alg_type == 'kex' and (n.startswith('ext-info-') or n.startswith('kex-strict-'))) or \
empty_version:
continue
rec[sshv][alg_type]['add'][n] = 0
else:
if faults == 0:
continue
if n in ['diffie-hellman-group-exchange-sha256', 'rsa-sha2-256', 'rsa-sha2-512', 'rsa-sha2-256-cert-v01@openssh.com', 'rsa-sha2-512-cert-v01@openssh.com']:
rec[sshv][alg_type]['chg'][n] = faults
else:
rec[sshv][alg_type]['del'][n] = faults
# If we are working with unknown software, drop all add recommendations, because we don't know if they're valid.
if unknown_software:
rec[sshv][alg_type]['add'] = {}
add_count = len(rec[sshv][alg_type]['add'])
del_count = len(rec[sshv][alg_type]['del'])
chg_count = len(rec[sshv][alg_type]['chg'])
if add_count == 0:
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:
del rec[sshv]
return software, rec
class Item:
def __init__(self, sshv: int, db: Dict[str, Dict[str, List[List[Optional[str]]]]]) -> None:
self.__sshv = sshv
self.__db = db
self.__storage: Dict[str, List[str]] = {}
@property
def sshv(self) -> int:
return self.__sshv
@property
def db(self) -> Dict[str, Dict[str, List[List[Optional[str]]]]]:
return self.__db
def add(self, key: str, value: List[str]) -> None:
self.__storage[key] = value
def items(self) -> Iterable[Tuple[str, List[str]]]:
return self.__storage.items()