Server kex/host key parsing failures no longer output a stack trace unless in debug mode.

Their certificate-embedded counterparts are enabled as well.

As with RSA, it *is* possible for DSA keys to be of variable length (not
just 1024 bits), so I've added `{'variable_key_len': True}` to the relevant
`HOST_KEY_TYPES` entries, although this key-value pair is otherwise unused.

.github/FUNDING.yml

@@ -0,0 +1 @@
+github: jtesta

README.md

@@ -1,10 +1,15 @@
 # ssh-audit
 [![License](https://img.shields.io/badge/license-MIT-brightgreen.svg)](https://github.com/jtesta/ssh-audit/blob/master/LICENSE)
-[![PyPI Downloads](https://img.shields.io/pypi/dm/ssh-audit?label=pypi%20downloads&color=purple)](https://pypi.org/project/ssh-audit/)
-[![Docker Pulls](https://img.shields.io/docker/pulls/positronsecurity/ssh-audit)](https://hub.docker.com/r/positronsecurity/ssh-audit)
 [![Build Status](https://github.com/jtesta/ssh-audit/actions/workflows/tox.yaml/badge.svg)](https://github.com/jtesta/ssh-audit/actions)
 [![PRs Welcome](https://img.shields.io/badge/PRs-welcome-brightgreen.svg)](https://github.com/jtesta/ssh-audit/blob/master/CONTRIBUTING.md)
 
+[![PyPI Downloads](https://img.shields.io/pypi/dm/ssh-audit?label=pypi%20downloads&color=purple)](https://pypi.org/project/ssh-audit/)
+[![Homebrew Downloads](https://img.shields.io/homebrew/installs/dy/ssh-audit?label=homebrew%20downloads&color=teal)](https://formulae.brew.sh/formula/ssh-audit)
+[![Docker Pulls](https://img.shields.io/docker/pulls/positronsecurity/ssh-audit)](https://hub.docker.com/r/positronsecurity/ssh-audit)
+[![Snap Downloads](https://img.shields.io/badge/snap%20downloads-no%20idea-yellow.svg)](https://snapcraft.io/ssh-audit)
+
+[![Github Sponsors](https://img.shields.io/github/sponsors/jtesta?color=red)](https://github.com/sponsors/jtesta)
+
 **ssh-audit** is a tool for ssh server & client configuration auditing.
 
 [jtesta/ssh-audit](https://github.com/jtesta/ssh-audit/) (v2.0+) is the updated and maintained version of ssh-audit forked from [arthepsy/ssh-audit](https://github.com/arthepsy/ssh-audit) (v1.x) due to inactivity.
@@ -32,7 +37,7 @@
 - historical information from OpenSSH, Dropbear SSH and libssh;
 - policy scans to ensure adherence to a hardened/standard configuration;
 - runs on Linux and Windows;
-- supports Python 3.8 - 3.12;
+- supports Python 3.8 - 3.13;
 - no dependencies
 
 ## Usage
@@ -89,7 +94,9 @@ usage: ssh-audit.py [options] <host>
    -t,  --timeout=<secs>   timeout (in seconds) for connection and reading
                                (default: 5)
    -T,  --targets=<hosts.txt>  a file containing a list of target hosts (one
-                                   per line, format HOST[:PORT])
+                                   per line, format HOST[:PORT]).  Use -p/--port
+                                   to set the default port for all hosts.  Use
+                                   --threads to control concurrent scans.
         --threads=<threads>    number of threads to use when scanning multiple
                                    targets (-T/--targets) (default: 32)
    -v,  --verbose          verbose output
@@ -224,6 +231,7 @@ For convenience, a web front-end on top of the command-line tool is available at
  - Fixed DHEat connection rate testing on MacOS X and BSD platforms; credit [Drew Noel](https://github.com/drewmnoel) and [Michael Osipov](https://github.com/michael-o).
  - Fixed invalid JSON output when a socket error occurs while performing a client audit.
  - When scanning multiple targets (using `-T`/`--targets`), the `-p`/`--port` option will now be used as the default port (set to 22 if `-p`/`--port` is not given).  Hosts specified in the file can override this default with an explicit port number (i.e.: "host1:1234").  For example, when using `-T targets.txt -p 222`, all hosts in `targets.txt` that do not explicitly include a port number will default to 222; when using `-T targets.txt` (without `-p`), all hosts will use a default of 22.
+ - Now reports ECDSA and DSS fingerprints when in verbose mode; partial credit [Daniel Lenski](https://github.com/dlenskiSB).
  - Added 1 new cipher: `grasshopper-ctr128`.
  - Added 2 new key exchanges: `mlkem768x25519-sha256`, `sntrup761x25519-sha512`.
 

src/ssh_audit/hostkeytest.py

@@ -1,7 +1,7 @@
 """
    The MIT License (MIT)
 
-   Copyright (C) 2017-2023 Joe Testa (jtesta@positronsecurity.com)
+   Copyright (C) 2017-2024 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
@@ -55,6 +55,17 @@ class HostKeyTest:
 
         'ssh-ed448':                      {'cert': False, 'variable_key_len': False},
         # 'ssh-ed448-cert-v01@openssh.com': {'cert': True,  'variable_key_len': False},
+
+        'ecdsa-sha2-nistp256': {'cert': False, 'variable_key_len': False},
+        'ecdsa-sha2-nistp384': {'cert': False, 'variable_key_len': False},
+        'ecdsa-sha2-nistp521': {'cert': False, 'variable_key_len': False},
+
+        'ecdsa-sha2-nistp256-cert-v01@openssh.com': {'cert': True, 'variable_key_len': False},
+        'ecdsa-sha2-nistp384-cert-v01@openssh.com': {'cert': True, 'variable_key_len': False},
+        'ecdsa-sha2-nistp521-cert-v01@openssh.com': {'cert': True, 'variable_key_len': False},
+
+        'ssh-dss':                      {'cert': False, 'variable_key_len': True},
+        'ssh-dss-cert-v01@openssh.com': {'cert': True,  'variable_key_len': True},
     }
 
     TWO2K_MODULUS_WARNING = '2048-bit modulus only provides 112-bits of symmetric strength'
@@ -140,7 +151,12 @@ class HostKeyTest:
                         _, payload = s.read_packet()
                         SSH2_Kex.parse(out, payload)
                     except Exception:
-                        out.v("Failed to parse server's kex.  Stack trace:\n%s" % str(traceback.format_exc()), write_now=True)
+                        msg = "Failed to parse server's kex."
+                        if not out.debug:
+                            msg += "  Re-run in debug mode to see stack trace."
+
+                        out.v(msg, write_now=True)
+                        out.d("Stack trace:\n%s" % str(traceback.format_exc()), write_now=True)
                         return
 
                 # Do the initial DH exchange.  The server responds back
@@ -151,7 +167,12 @@ class HostKeyTest:
                     kex_reply = kex_group.recv_reply(s)
                     raw_hostkey_bytes = kex_reply if kex_reply is not None else b''
                 except KexDHException:
-                    out.v("Failed to parse server's host key.  Stack trace:\n%s" % str(traceback.format_exc()), write_now=True)
+                    msg = "Failed to parse server's host key."
+                    if not out.debug:
+                        msg += "  Re-run in debug mode to see stack trace."
+
+                    out.v(msg, write_now=True)
+                    out.d("Stack trace:\n%s" % str(traceback.format_exc()), write_now=True)
 
                     # Since parsing this host key failed, there's nothing more to do but close the socket and move on to the next host key type.
                     s.close()
@@ -191,7 +212,7 @@ class HostKeyTest:
                         cakey_warn_str = HostKeyTest.SMALL_ECC_MODULUS_WARNING
 
                     # 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 < hostkey_min_good):
+                    if (cert is False) and (hostkey_modulus_size < hostkey_min_good) and (host_key_type != 'ssh-dss'):  # Skip ssh-dss, otherwise we get duplicate failure messages (SSH2_KexDB will always flag it).
 
                         # If the key is under 2048, add to the failure list.
                         if hostkey_modulus_size < hostkey_min_warn:

src/ssh_audit/ssh_audit.py

@@ -360,11 +360,19 @@ def output_fingerprints(out: OutputBuffer, algs: Algorithms, is_json_output: boo
         fp_types = sorted(fps.keys())
         for fp_type in fp_types:
             fp = fps[fp_type]
-            out.good('(fin) {}: {}'.format(fp_type, fp.sha256))
+
+            # Don't output any ECDSA or DSS fingerprints unless verbose mode is enabled.
+            if fp_type.startswith("ecdsa-") or (fp_type == "ssh-dss"):
+                if out.verbose:
+                    out.warn('(fin) {}: {} -- [info] this fingerprint type is insecure and should not be relied upon'.format(fp_type, fp.sha256))
+                else:
+                    continue  # If verbose mode is not enabled, skip this type entirely.
+            else:
+                out.good('(fin) {}: {}'.format(fp_type, fp.sha256))
 
             # Output the MD5 hash too if verbose mode is enabled.
             if out.verbose:
-                out.info('(fin) {}: {} -- [info] do not rely on MD5 fingerprints for server identification; it is insecure for this use case'.format(fp_type, fp.md5))
+                out.warn('(fin) {}: {} -- [info] do not rely on MD5 fingerprints for server identification; it is insecure for this use case'.format(fp_type, fp.md5))
 
     if not out.is_section_empty() and not is_json_output:
         out.head('# fingerprints')

test/docker/expected_results/dropbear_2019.78_test1.json

@@ -78,6 +78,26 @@
         }
     ],
     "fingerprints": [
+        {
+            "hash": "jdUfqoGCDOY1drQcoqIJm/pEix2r09hqwOs9E9GimZQ",
+            "hash_alg": "SHA256",
+            "hostkey": "ecdsa-sha2-nistp256"
+        },
+        {
+            "hash": "98:27:f3:12:20:f6:23:6d:1a:00:2a:6c:71:7c:1e:6b",
+            "hash_alg": "MD5",
+            "hostkey": "ecdsa-sha2-nistp256"
+        },
+        {
+            "hash": "NBzry0uMAX8BRsn4mv9CHpeivMOdwzGFEKrf6Hg7tIQ",
+            "hash_alg": "SHA256",
+            "hostkey": "ssh-dss"
+        },
+        {
+            "hash": "16:60:9e:54:d7:1e:b3:0d:97:60:12:ad:fe:83:a2:40",
+            "hash_alg": "MD5",
+            "hostkey": "ssh-dss"
+        },
         {
             "hash": "CDfAU12pjQS7/91kg7gYacza0U/6PDbE04Ic3IpYxkM",
             "hash_alg": "SHA256",

test/docker/expected_results/openssh_4.0p1_test1.json

@@ -253,6 +253,16 @@
         }
     ],
     "fingerprints": [
+        {
+            "hash": "sqDDYhzYz7YIQeFDc0WF8SeXtrEz+iwsV7d/FdIgztM",
+            "hash_alg": "SHA256",
+            "hostkey": "ssh-dss"
+        },
+        {
+            "hash": "5c:de:62:f0:60:c8:93:13:87:71:78:95:56:3f:61:51",
+            "hash_alg": "MD5",
+            "hostkey": "ssh-dss"
+        },
         {
             "hash": "YZ457EBcJTSxRKI3yXRgtAj3PBf5B9/F36b1SVooml4",
             "hash_alg": "SHA256",

test/docker/expected_results/openssh_5.6p1_test1.json

@@ -240,6 +240,16 @@
         }
     ],
     "fingerprints": [
+        {
+            "hash": "sqDDYhzYz7YIQeFDc0WF8SeXtrEz+iwsV7d/FdIgztM",
+            "hash_alg": "SHA256",
+            "hostkey": "ssh-dss"
+        },
+        {
+            "hash": "5c:de:62:f0:60:c8:93:13:87:71:78:95:56:3f:61:51",
+            "hash_alg": "MD5",
+            "hostkey": "ssh-dss"
+        },
         {
             "hash": "YZ457EBcJTSxRKI3yXRgtAj3PBf5B9/F36b1SVooml4",
             "hash_alg": "SHA256",

test/docker/expected_results/openssh_8.0p1_test1.json

@@ -87,6 +87,16 @@
         }
     ],
     "fingerprints": [
+        {
+            "hash": "Q6Llm0o4TrcUen4tnT2h4BDf2f+ina6dIJmVH8c40bg",
+            "hash_alg": "SHA256",
+            "hostkey": "ecdsa-sha2-nistp256"
+        },
+        {
+            "hash": "cc:e0:80:84:5b:05:98:64:24:43:52:3b:17:c8:94:89",
+            "hash_alg": "MD5",
+            "hostkey": "ecdsa-sha2-nistp256"
+        },
         {
             "hash": "UrnXIVH+7dlw8UqYocl48yUEcKrthGDQG2CPCgp7MxU",
             "hash_alg": "SHA256",