From 992aa1b961c2de4e19a056c6ebbc59c86a57220a Mon Sep 17 00:00:00 2001 From: Joe Testa Date: Tue, 21 Mar 2023 22:17:23 -0400 Subject: [PATCH] Added support for kex GSS wildcards (#143). --- src/ssh_audit/ssh2_kexdb.py | 21 +++------------------ src/ssh_audit/ssh_audit.py | 10 ++++++++++ test/test_ssh2.py | 36 ++++++++++++++++++++++++++++++++++++ 3 files changed, 49 insertions(+), 18 deletions(-) diff --git a/src/ssh_audit/ssh2_kexdb.py b/src/ssh_audit/ssh2_kexdb.py index de2c5cc..37f1dca 100644 --- a/src/ssh_audit/ssh2_kexdb.py +++ b/src/ssh_audit/ssh2_kexdb.py @@ -71,29 +71,13 @@ class SSH2_KexDB: # pylint: disable=too-few-public-methods ALGORITHMS: Dict[str, Dict[str, List[List[Optional[str]]]]] = { # Format: 'algorithm_name': [['version_first_appeared_in'], [reason_for_failure1, reason_for_failure2, ...], [warning1, warning2, ...], [info1, info2, ...]] 'kex': { - 'diffie-hellman-group1-sha1': [['2.3.0,d0.28,l10.2', '6.6', '6.9'], [FAIL_1024BIT_MODULUS, FAIL_OPENSSH67_UNSAFE, FAIL_OPENSSH70_LOGJAM], [WARN_HASH_WEAK]], - 'gss-group1-sha1-toWM5Slw5Ew8Mqkay+al2g==': [[], [FAIL_1024BIT_MODULUS, FAIL_OPENSSH67_UNSAFE, FAIL_OPENSSH70_LOGJAM], [WARN_HASH_WEAK]], - 'gss-gex-sha1-eipGX3TCiQSrx573bT1o1Q==': [[], [], [WARN_HASH_WEAK]], - 'gss-gex-sha1-toWM5Slw5Ew8Mqkay+al2g==': [[], [], [WARN_HASH_WEAK]], - 'gss-gex-sha1-': [[], [], [WARN_HASH_WEAK]], - 'gss-group1-sha1-eipGX3TCiQSrx573bT1o1Q==': [[], [FAIL_1024BIT_MODULUS], [WARN_HASH_WEAK]], - 'gss-group1-sha1-': [[], [FAIL_1024BIT_MODULUS], [WARN_HASH_WEAK]], - 'gss-group14-sha1-': [[], [], [WARN_HASH_WEAK, WARN_2048BIT_MODULUS]], - 'gss-group14-sha1-eipGX3TCiQSrx573bT1o1Q==': [[], [], [WARN_HASH_WEAK, WARN_2048BIT_MODULUS]], - 'gss-group14-sha1-toWM5Slw5Ew8Mqkay+al2g==': [[], [], [WARN_HASH_WEAK, WARN_2048BIT_MODULUS]], - 'gss-group14-sha256-': [[], [], [WARN_2048BIT_MODULUS]], - 'gss-group14-sha256-toWM5Slw5Ew8Mqkay+al2g==': [[], [], [WARN_2048BIT_MODULUS]], - 'gss-group15-sha512-': [[]], - 'gss-group15-sha512-toWM5Slw5Ew8Mqkay+al2g==': [[]], - 'gss-group16-sha512-': [[]], - 'gss-nistp256-sha256-': [[], [FAIL_CURVES_WEAK]], - 'gss-curve25519-sha256-': [[]], + # The GSS kex algorithms get special wildcard handling, since they include variable base64 data after their standard prefixes. 'gss-13.3.132.0.10-sha256-*': [[], [FAIL_UNKNOWN]], 'gss-curve25519-sha256-*': [[]], 'gss-curve448-sha512-*': [[]], 'gss-gex-sha1-*': [[], [], [WARN_HASH_WEAK]], 'gss-gex-sha256-*': [[]], - 'gss-group1-sha1-*': [[], [FAIL_1024BIT_MODULUS], [WARN_HASH_WEAK]], + 'gss-group1-sha1-*': [[], [FAIL_1024BIT_MODULUS, FAIL_OPENSSH67_UNSAFE, FAIL_OPENSSH70_LOGJAM], [WARN_HASH_WEAK]], 'gss-group14-sha1-*': [[], [], [WARN_HASH_WEAK, WARN_2048BIT_MODULUS]], 'gss-group14-sha256-*': [[], [], [WARN_2048BIT_MODULUS]], 'gss-group15-sha512-*': [[]], @@ -103,6 +87,7 @@ class SSH2_KexDB: # pylint: disable=too-few-public-methods 'gss-nistp256-sha256-*': [[], [FAIL_CURVES_WEAK]], 'gss-nistp384-sha256-*': [[], [FAIL_CURVES_WEAK]], 'gss-nistp521-sha512-*': [[], [FAIL_CURVES_WEAK]], + 'diffie-hellman-group1-sha1': [['2.3.0,d0.28,l10.2', '6.6', '6.9'], [FAIL_1024BIT_MODULUS, FAIL_OPENSSH67_UNSAFE, FAIL_OPENSSH70_LOGJAM], [WARN_HASH_WEAK]], 'diffie-hellman-group1-sha256': [[], [FAIL_1024BIT_MODULUS]], 'diffie-hellman-group14-sha1': [['3.9,d0.53,l10.6.0'], [], [WARN_HASH_WEAK, WARN_2048BIT_MODULUS]], 'diffie-hellman-group14-sha256': [['7.3,d2016.73'], [], [WARN_2048BIT_MODULUS]], diff --git a/src/ssh_audit/ssh_audit.py b/src/ssh_audit/ssh_audit.py index 3f9880c..e3bc291 100755 --- a/src/ssh_audit/ssh_audit.py +++ b/src/ssh_audit/ssh_audit.py @@ -137,6 +137,12 @@ def output_algorithm(out: OutputBuffer, alg_db: Dict[str, Dict[str, List[List[Op alg_name_with_size = '%s (%d-bit)' % (alg_name, hostkey_size) padding = padding[0:-11] + # If this is a kex algorithm and starts with 'gss-', then normalize its name (i.e.: 'gss-gex-sha1-vz8J1E9PzLr8b1K+0remTg==' => 'gss-gex-sha1-*'). The base64 field can vary, so we'll convert it to the wildcard that our database uses and we'll just resume doing a straight match like all other algorithm names. + alg_name_original = alg_name + if alg_type == 'kex' and alg_name.startswith('gss-'): + last_dash = alg_name.rindex('-') + alg_name = "%s-*" % alg_name[0:last_dash] + texts = [] if len(alg_name.strip()) == 0: return program_retval @@ -162,6 +168,10 @@ def output_algorithm(out: OutputBuffer, alg_db: Dict[str, Dict[str, List[List[Op texts.append(('warn', 'unknown algorithm')) unknown_algs.append(alg_name) + # For kex GSS algorithms, now that we already did the database lookup (above), restore the original algorithm name so its reported properly in the output. + if alg_name != alg_name_original: + alg_name = alg_name_original + alg_name = alg_name_with_size if alg_name_with_size is not None else alg_name first = True for level, text in texts: diff --git a/test/test_ssh2.py b/test/test_ssh2.py index d4c4b84..b1a7767 100644 --- a/test/test_ssh2.py +++ b/test/test_ssh2.py @@ -61,6 +61,23 @@ class TestSSH2: w.write_int(0) return w.write_flush() + def _kex_payload_with_gss(self): + w = self.wbuf() + w.write(b'\x00\x11\x22\x33\x44\x55\x66\x77\x88\x99\xaa\xbb\xcc\xdd\xee\xff') + w.write_list(['gss-gex-sha1-dZuIebMjgUqaxvbF7hDbAw==', 'gss-gex-sha1-vz8J1E9PzLr8b1K+0remTg==', 'gss-group14-sha1-dZuIebMjgUqaxvbF7hDbAw==', 'gss-group14-sha1-vz8J1E9PzLr8b1K+0remTg==', 'gss-group14-sha256-dZuIebMjgUqaxvbF7hDbAw==', 'gss-group14-sha256-vz8J1E9PzLr8b1K+0remTg==', 'gss-group16-sha512-dZuIebMjgUqaxvbF7hDbAw==', 'gss-group16-sha512-vz8J1E9PzLr8b1K+0remTg==', 'gss-group18-sha512-dZuIebMjgUqaxvbF7hDbAw==', 'gss-group18-sha512-vz8J1E9PzLr8b1K+0remTg==', 'gss-group1-sha1-dZuIebMjgUqaxvbF7hDbAw==', 'gss-group1-sha1-vz8J1E9PzLr8b1K+0remTg==', 'gss-curve448-sha512-XXX']) + w.write_list(['ssh-ed25519']) + w.write_list(['chacha20-poly1305@openssh.com']) + w.write_list(['chacha20-poly1305@openssh.com']) + w.write_list(['hmac-sha2-512-etm@openssh.com']) + w.write_list(['hmac-sha2-512-etm@openssh.com']) + w.write_list(['none', 'zlib@openssh.com']) + w.write_list(['none', 'zlib@openssh.com']) + w.write_list(['']) + w.write_list(['']) + w.write_byte(False) + w.write_int(0) + return w.write_flush() + def test_kex_read(self): kex = self.ssh2_kex.parse(self._kex_payload()) assert kex is not None @@ -163,3 +180,22 @@ class TestSSH2: lines = output_spy.flush() assert len(lines) == 9 assert 'unknown message' in lines[-1] + + def test_ssh2_gss_kex(self, output_spy, virtual_socket): + '''Ensure that GSS kex algorithms are properly parsed.''' + + vsocket = virtual_socket + w = self.wbuf() + w.write_byte(self.protocol.MSG_KEXINIT) + w.write(self._kex_payload_with_gss()) # Use the kex with GSS algorithms. + vsocket.rdata.append(b'SSH-2.0-OpenSSH_7.3 ssh-audit-test\r\n') + vsocket.rdata.append(self._create_ssh2_packet(w.write_flush())) + output_spy.begin() + out = self.OutputBuffer() + self.audit(out, self._conf()) + out.write() + lines = output_spy.flush() + + # Ensure that none of the lines are reported as "unknown algorithm". + for line in lines: + assert line.find('unknown algorithm') == -1