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Streamlined sending of KEXINIT messages.

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This commit is contained in:
Joe Testa 2021-01-21 11:23:40 -05:00
parent bbbd75ee69
commit bbb81e24ab
4 changed files with 5 additions and 21 deletions
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7
src/ssh_audit/gextest.py
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@ -21,14 +21,12 @@
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
"""
import os
# 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.kexdh import KexGroupExchange_SHA1, KexGroupExchange_SHA256
from ssh_audit.protocol import Protocol
from ssh_audit.ssh2_kexdb import SSH2_KexDB
from ssh_audit.ssh2_kex import SSH2_Kex
from ssh_audit.ssh_socket import SSH_Socket
@ -55,10 +53,7 @@ class GEXTest:
# 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, False, 0)
s.write_byte(Protocol.MSG_KEXINIT)
client_kex.write(s)
s.send_packet()
s.send_kexinit(key_exchanges=[gex_alg], hostkeys=kex.key_algorithms, ciphers=kex.server.encryption, macs=kex.server.mac, compressions=kex.server.compression, languages=kex.server.languages)
# Parse the server's KEX.
_, payload = s.read_packet(2)

7
src/ssh_audit/hostkeytest.py
View File

@ -21,14 +21,12 @@
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
"""
import os
# 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.kexdh import KexDH, KexGroup1, KexGroup14_SHA1, KexGroup14_SHA256, KexCurve25519_SHA256, KexGroup16_SHA512, KexGroup18_SHA512, KexGroupExchange_SHA1, KexGroupExchange_SHA256, KexNISTP256, KexNISTP384, KexNISTP521
from ssh_audit.protocol import Protocol
from ssh_audit.ssh2_kex import SSH2_Kex
from ssh_audit.ssh2_kexdb import SSH2_KexDB
from ssh_audit.ssh_socket import SSH_Socket
@ -118,10 +116,7 @@ class HostKeyTest:
return
# Send our KEX using the specified group-exchange and most of the server's own values.
client_kex = SSH2_Kex(os.urandom(16), [kex_str], [host_key_type], server_kex.client, server_kex.server, False, 0)
s.write_byte(Protocol.MSG_KEXINIT)
client_kex.write(s)
s.send_packet()
s.send_kexinit(key_exchanges=[kex_str], hostkeys=[host_key_type], ciphers=server_kex.server.encryption, macs=server_kex.server.mac, compressions=server_kex.server.compression, languages=server_kex.server.languages)
# Parse the server's KEX.
_, payload = s.read_packet()

2
src/ssh_audit/ssh_audit.py
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@ -798,7 +798,7 @@ def audit(aconf: AuditConf, sshv: Optional[int] = None, print_target: bool = Fal
else:
err = '[exception] did not receive banner: {}'.format(err)
if err is None:
s.send_algorithms() # Send the algorithms we support (except we don't since this isn't a real SSH connection).
s.send_kexinit() # Send the algorithms we support (except we don't since this isn't a real SSH connection).
packet_type, payload = s.read_packet(sshv)
if packet_type < 0:

10
src/ssh_audit/ssh_socket.py
View File

@ -230,16 +230,10 @@ class SSH_Socket(ReadBuf, WriteBuf):
except socket.error as e:
return -1, str(e.args[-1])
def send_algorithms(self) -> None:
# Send a KEXINIT with the lists of key exchanges, hostkeys, ciphers, MACs, compressions, and languages that we "support".
def send_kexinit(self, key_exchanges: List[str] = ['curve25519-sha256', 'curve25519-sha256@libssh.org', 'ecdh-sha2-nistp256', 'ecdh-sha2-nistp384', 'ecdh-sha2-nistp521', 'diffie-hellman-group-exchange-sha256', 'diffie-hellman-group16-sha512', 'diffie-hellman-group18-sha512', 'diffie-hellman-group14-sha256'], hostkeys: List[str] = ['rsa-sha2-512', 'rsa-sha2-256', 'ssh-rsa', 'ecdsa-sha2-nistp256', 'ssh-ed25519'], ciphers: List[str] = ['chacha20-poly1305@openssh.com', 'aes128-ctr', 'aes192-ctr', 'aes256-ctr', 'aes128-gcm@openssh.com', 'aes256-gcm@openssh.com'], macs: List[str] = ['umac-64-etm@openssh.com', 'umac-128-etm@openssh.com', 'hmac-sha2-256-etm@openssh.com', 'hmac-sha2-512-etm@openssh.com', 'hmac-sha1-etm@openssh.com', 'umac-64@openssh.com', 'umac-128@openssh.com', 'hmac-sha2-256', 'hmac-sha2-512', 'hmac-sha1'], compressions: List[str] = ['none', 'zlib@openssh.com'], languages: List[str] = ['']) -> None: # pylint: disable=dangerous-default-value
'''Sends the list of supported host keys, key exchanges, ciphers, and MACs. Emulates OpenSSH v8.2.'''
key_exchanges = ['curve25519-sha256', 'curve25519-sha256@libssh.org', 'ecdh-sha2-nistp256', 'ecdh-sha2-nistp384', 'ecdh-sha2-nistp521', 'diffie-hellman-group-exchange-sha256', 'diffie-hellman-group16-sha512', 'diffie-hellman-group18-sha512', 'diffie-hellman-group14-sha256']
hostkeys = ['rsa-sha2-512', 'rsa-sha2-256', 'ssh-rsa', 'ecdsa-sha2-nistp256', 'ssh-ed25519']
ciphers = ['chacha20-poly1305@openssh.com', 'aes128-ctr', 'aes192-ctr', 'aes256-ctr', 'aes128-gcm@openssh.com', 'aes256-gcm@openssh.com']
macs = ['umac-64-etm@openssh.com', 'umac-128-etm@openssh.com', 'hmac-sha2-256-etm@openssh.com', 'hmac-sha2-512-etm@openssh.com', 'hmac-sha1-etm@openssh.com', 'umac-64@openssh.com', 'umac-128@openssh.com', 'hmac-sha2-256', 'hmac-sha2-512', 'hmac-sha1']
compressions = ['none', 'zlib@openssh.com']
languages = ['']
kexparty = SSH2_KexParty(ciphers, macs, compressions, languages)
kex = SSH2_Kex(os.urandom(16), key_exchanges, hostkeys, kexparty, kexparty, False, 0)