Git/ssh-audit
1
0
Fork 0
mirror of https://github.com/jtesta/ssh-audit.git synced 2025-09-03 18:38:32 +02:00
Code Issues Packages Projects Releases Wiki Activity

Now issues a warning when 2048-bit moduli are encountered.

Browse Source
This commit is contained in:
Joe Testa
2023-02-06 16:27:30 -05:00
parent f9e00b6f2d
commit c9dc9a9c10
17 changed files with 93 additions and 42 deletions
Download Patch File Download Diff File Expand all files Collapse all files

33
src/ssh_audit/hostkeytest.py
View File

@ -1,7 +1,7 @@
"""
The MIT License (MIT)
Copyright (C) 2017-2021 Joe Testa (jtesta@positronsecurity.com)
Copyright (C) 2017-2023 Joe Testa (jtesta@positronsecurity.com)
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
@ -54,6 +54,9 @@ class HostKeyTest:
'ssh-ed25519-cert-v01@openssh.com': {'cert': True, 'variable_key_len': False},
}
TWO2K_MODULUS_WARNING = '2048-bit modulus only provides 112-bits of symmetric strength'
@staticmethod
def run(out: 'OutputBuffer', s: 'SSH_Socket', server_kex: 'SSH2_Kex') -> None:
KEX_TO_DHGROUP = {
@ -161,24 +164,34 @@ class HostKeyTest:
elif cert is True:
server_kex.set_rsa_key_size(host_key_type, hostkey_modulus_size, ca_modulus_size)
# Keys smaller than 2048 result in a failure. Update the database accordingly.
if (cert is False) and (hostkey_modulus_size < 2048):
# Keys smaller than 2048 result in a failure. Keys smaller 3072 result in a warning. Update the database accordingly.
if (cert is False) and (hostkey_modulus_size < 3072):
for rsa_type in HostKeyTest.RSA_FAMILY:
alg_list = SSH2_KexDB.ALGORITHMS['key'][rsa_type]
# If no failure list exists, add an empty failure list.
if len(alg_list) < 2:
# Ensure that failure & warning lists exist.
while len(alg_list) < 3:
alg_list.append([])
alg_list[1].append('using small %d-bit modulus' % hostkey_modulus_size)
elif (cert is True) and ((hostkey_modulus_size < 2048) or (ca_modulus_size > 0 and ca_modulus_size < 2048)): # pylint: disable=chained-comparison
# If the key is under 2048, add to the failure list.
if hostkey_modulus_size < 2048:
alg_list[1].append('using small %d-bit modulus' % hostkey_modulus_size)
elif HostKeyTest.TWO2K_MODULUS_WARNING not in alg_list[2]: # Issue a warning about 2048-bit moduli.
alg_list[2].append(HostKeyTest.TWO2K_MODULUS_WARNING)
elif (cert is True) and ((hostkey_modulus_size < 3072) or (ca_modulus_size > 0 and ca_modulus_size < 3072)): # pylint: disable=chained-comparison
alg_list = SSH2_KexDB.ALGORITHMS['key'][host_key_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)
# If no failure list exists, add an empty failure list.
if len(alg_list) < 2:
# Ensure that failure & warning lists exist.
while len(alg_list) < 3:
alg_list.append([])
alg_list[1].append('using small %d-bit modulus' % min_modulus)
if (hostkey_modulus_size < 2048) or (ca_modulus_size > 0 and ca_modulus_size < 2048): # pylint: disable=chained-comparison
alg_list[1].append('using small %d-bit modulus' % min_modulus)
elif HostKeyTest.TWO2K_MODULUS_WARNING not in alg_list[2]:
alg_list[2].append(HostKeyTest.TWO2K_MODULUS_WARNING)
# If this host key type is in the RSA family, then mark them all as parsed (since results in one are valid for them all).
if host_key_type in HostKeyTest.RSA_FAMILY: