Merge pull request #139 from dev-sec/macs_kex_ciphers

Macs kex ciphers
dev-sec · Dec 29, 2017 · eaab080 · eaab080
2 parents 92a23e1 + 9bf929b
commit eaab080
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diff --git a/.travis.yml b/.travis.yml
@@ -54,6 +54,7 @@ script:
   - 'docker run --detach --volume="${PWD}":/etc/ansible/roles/ansible-ssh-hardening:ro ${run_opts} rndmh3ro/docker-${distro}-ansible:${version} "${init}" > "${container_id}"'
 
   # Test role.
+  - 'docker exec "$(cat ${container_id})" ansible-playbook /etc/ansible/roles/ansible-ssh-hardening/default_custom.yml'
   - 'docker exec "$(cat ${container_id})" ansible-playbook /etc/ansible/roles/ansible-ssh-hardening/default.yml'
 
   # Verify role

diff --git a/default.yml b/default.yml
@@ -1,5 +1,5 @@
 ---
-- name: wrapper playbook for kitchen testing "ansible-ssh-hardening" with custom settings
+- name: wrapper playbook for kitchen testing "ansible-ssh-hardening" with default settings
   hosts: localhost
   pre_tasks:
     - package: name="{{item}}" state=installed
@@ -19,48 +19,3 @@
 
   roles:
     - ansible-ssh-hardening
-  vars:
-    network_ipv6_enable: true
-    ssh_allow_root_with_key: true
-    ssh_allow_tcp_forwarding: true
-    ssh_gateway_ports: true
-    ssh_allow_agent_forwarding: true
-    ssh_server_permit_environment_vars: ['PWD','HTTP_PROXY']
-    ssh_client_alive_interval: 100
-    ssh_client_alive_count: 10
-    ssh_client_password_login: true
-    ssh_client_cbc_required: true
-    ssh_client_weak_kex: true
-    ssh_challengeresponseauthentication: true
-    ssh_compression: true
-    ssh_allow_users: 'root kitchen vagrant'
-    ssh_allow_groups: 'root kitchen vagrant'
-    ssh_deny_users: 'foo bar'
-    ssh_deny_groups: 'foo bar'
-    ssh_authorized_keys_file: '/etc/ssh/authorized_keys/%u'
-    ssh_max_auth_retries: 10
-    ssh_permit_tunnel: true
-    ssh_print_motd: true
-    ssh_print_last_log: true
-    ssh_banner: true
-    ssh_server_password_login: true
-    ssh_server_weak_hmac: true
-    sftp_enabled: true
-    ssh_server_match_group:
-      - group: 'root'
-        rules: 'AllowTcpForwarding yes'
-    ssh_server_match_user:
-      - user: 'root'
-        rules: 'AllowTcpForwarding yes'
-    ssh_remote_hosts:
-      - names: ['example.com', 'example2.com']
-        options: ['Port 2222', 'ForwardAgent yes']
-      - names: ['example3.com']
-        options: ['StrictHostKeyChecking no']
-    ssh_use_dns: true
-    ssh_use_pam: true
-
-- name: wrapper playbook for kitchen testing "ansible-ssh-hardening" with default settings
-  hosts: localhost
-  roles:
-    - ansible-ssh-hardening
diff --git a/default_custom.yml b/default_custom.yml
@@ -0,0 +1,62 @@
+---
+- name: wrapper playbook for kitchen testing "ansible-ssh-hardening" with custom settings
+  hosts: localhost
+  pre_tasks:
+    - package: name="{{item}}" state=installed
+      with_items:
+        - "openssh-clients"
+        - "openssh-server"
+      ignore_errors: true
+    - apt: name="{{item}}" state=installed update_cache=true
+      with_items:
+        - "openssh-client"
+        - "openssh-server"
+      ignore_errors: true
+    - file: path="/var/run/sshd" state=directory
+    - name: create ssh host keys
+      command: "ssh-keygen -A"
+      when: not ((ansible_os_family in ['Oracle Linux', 'RedHat']) and ansible_distribution_major_version < '7')
+
+  roles:
+    - ansible-ssh-hardening
+  vars:
+    network_ipv6_enable: true
+    ssh_allow_root_with_key: true
+    ssh_allow_tcp_forwarding: true
+    ssh_gateway_ports: true
+    ssh_allow_agent_forwarding: true
+    ssh_server_permit_environment_vars: ['PWD','HTTP_PROXY']
+    ssh_client_alive_interval: 100
+    ssh_client_alive_count: 10
+    ssh_client_password_login: true
+    ssh_client_cbc_required: true
+    ssh_client_weak_kex: true
+    ssh_challengeresponseauthentication: true
+    ssh_compression: true
+    ssh_allow_users: 'root kitchen vagrant'
+    ssh_allow_groups: 'root kitchen vagrant'
+    ssh_deny_users: 'foo bar'
+    ssh_deny_groups: 'foo bar'
+    ssh_authorized_keys_file: '/etc/ssh/authorized_keys/%u'
+    ssh_max_auth_retries: 10
+    ssh_permit_tunnel: true
+    ssh_print_motd: true
+    ssh_print_last_log: true
+    ssh_banner: true
+    ssh_server_password_login: true
+    ssh_server_weak_hmac: true
+    sftp_enabled: true
+    ssh_server_enabled: false
+    ssh_server_match_group:
+      - group: 'root'
+        rules: 'AllowTcpForwarding yes'
+    ssh_server_match_user:
+      - user: 'root'
+        rules: 'AllowTcpForwarding yes'
+    ssh_remote_hosts:
+      - names: ['example.com', 'example2.com']
+        options: ['Port 2222', 'ForwardAgent yes']
+      - names: ['example3.com']
+        options: ['StrictHostKeyChecking no']
+    ssh_use_dns: true
+    ssh_use_pam: true
diff --git a/defaults/main.yml b/defaults/main.yml
@@ -127,6 +127,10 @@ ssh_server_permit_environment_vars: false
 ssh_ps53: 'yes'
 ssh_ps59: 'sandbox'
 
+ssh_macs: []
+ssh_ciphers: []
+ssh_kex: []
+
 ssh_macs_53_default:
   - hmac-ripemd160
   - hmac-sha1
@@ -141,11 +145,16 @@ ssh_macs_59_weak: "{{ ssh_macs_59_default + ['hmac-sha1'] }}"
 ssh_macs_66_default:
   - hmac-sha2-512-etm@openssh.com
   - hmac-sha2-256-etm@openssh.com
-  - hmac-ripemd160-etm@openssh.com
   - umac-128-etm@openssh.com
   - hmac-sha2-512
   - hmac-sha2-256
-  - hmac-ripemd160
+
+ssh_macs_76_default:
+  - hmac-sha2-512-etm@openssh.com
+  - hmac-sha2-256-etm@openssh.com
+  - umac-128-etm@openssh.com
+  - hmac-sha2-512
+  - hmac-sha2-256
 
 ssh_macs_66_weak: "{{ ssh_macs_66_default + ['hmac-sha1'] }}"
 

diff --git a/tasks/crypto.yml b/tasks/crypto.yml
@@ -0,0 +1,98 @@
+---
+
+- name: set hostkeys according to openssh-version
+  set_fact:
+    ssh_host_key_files: ['/etc/ssh/ssh_host_rsa_key', '/etc/ssh/ssh_host_ecdsa_key', '/etc/ssh/ssh_host_ed25519_key']
+  when: sshd_version.stdout >= '6.3' and not ssh_host_key_files
+
+- name: set hostkeys according to openssh-version
+  set_fact:
+    ssh_host_key_files: ['/etc/ssh/ssh_host_rsa_key', '/etc/ssh/ssh_host_ecdsa_key']
+  when: sshd_version.stdout >= '6.0' and not ssh_host_key_files
+
+- name: set hostkeys according to openssh-version
+  set_fact:
+    ssh_host_key_files: ['/etc/ssh/ssh_host_rsa_key']
+  when: sshd_version.stdout >= '5.3' and not ssh_host_key_files
+
+###
+
+- name: set weak macs according to openssh-version if openssh >= 7.6
+  set_fact:
+    ssh_macs: "{{ssh_macs_76_default}}"
+  when: sshd_version.stdout >= '7.6' and not ssh_macs
+
+- name: set weak macs according to openssh-version if openssh >= 6.6
+  set_fact:
+    ssh_macs: "{{ssh_macs_66_weak}}"
+  when: sshd_version.stdout >= '6.6' and ssh_server_weak_hmac and not ssh_macs
+
+- name: set macs according to openssh-version if openssh >= 6.6
+  set_fact:
+    ssh_macs: "{{ssh_macs_66_default}}"
+  when: sshd_version.stdout >= '6.6' and not ssh_macs
+
+- name: set weak macs according to openssh-version
+  set_fact:
+    ssh_macs: "{{ssh_macs_59_weak}}"
+  when: sshd_version.stdout >= '5.9' and ssh_server_weak_hmac and not ssh_macs
+
+- name: set macs according to openssh-version
+  set_fact:
+    ssh_macs: "{{ssh_macs_59_default}}"
+  when: sshd_version.stdout >= '5.9' and not ssh_macs
+
+- name: set macs according to openssh-version
+  set_fact:
+    ssh_macs: "{{ssh_macs_53_default}}"
+  when: sshd_version.stdout >= '5.3' and not ssh_macs
+
+- name: set macs according to openssh-version
+  set_fact:
+    ssh_macs: "{{ssh_macs_53_default}}"
+  when: sshd_version.stdout >= '5.3' and not ssh_macs
+
+###
+
+- name: set weak ciphers according to openssh-version if openssh >= 6.6
+  set_fact:
+    ssh_ciphers: "{{ssh_ciphers_66_weak}}"
+  when: sshd_version.stdout >= '6.6' and ssh_server_cbc_required and not ssh_ciphers
+
+- name: set ciphers according to openssh-version if openssh >= 6.6
+  set_fact:
+    ssh_ciphers: "{{ssh_ciphers_66_default}}"
+  when: sshd_version.stdout >= '6.6' and not ssh_ciphers
+
+- name: set weak ciphers according to openssh-version
+  set_fact:
+    ssh_ciphers: "{{ssh_ciphers_53_weak}}"
+  when: sshd_version.stdout >= '5.3' and ssh_server_cbc_required and not ssh_ciphers
+
+- name: set ciphers according to openssh-version
+  set_fact:
+    ssh_ciphers: "{{ssh_ciphers_53_default}}"
+  when: sshd_version.stdout >= '5.3' and not ssh_ciphers
+
+###
+
+- name: set weak kex according to openssh-version if openssh >= 6.6
+  set_fact:
+    ssh_kex: "{{ssh_kex_66_weak}}"
+  when: sshd_version.stdout >= '6.6' and ssh_server_weak_hmac and not ssh_kex
+
+- name: set kex according to openssh-version if openssh >= 6.6
+  set_fact:
+    ssh_kex: "{{ssh_kex_66_default}}"
+  when: sshd_version.stdout >= '6.6' and not ssh_kex
+
+- name: set weak kex according to openssh-version
+  set_fact:
+    ssh_kex: "{{ssh_kex_59_weak}}"
+  when: sshd_version.stdout >= '5.9' and ssh_server_weak_hmac and not ssh_kex
+
+- name: set kex according to openssh-version
+  set_fact:
+    ssh_kex: "{{ssh_kex_59_default}}"
+  when: sshd_version.stdout >= '5.9' and not ssh_kex
+
diff --git a/tasks/main.yml b/tasks/main.yml
@@ -15,20 +15,7 @@
   register: sshd_version
   check_mode: no
 
-- name: set hostkeys according to openssh-version
-  set_fact:
-    ssh_host_key_files: ['/etc/ssh/ssh_host_rsa_key', '/etc/ssh/ssh_host_ecdsa_key', '/etc/ssh/ssh_host_ed25519_key']
-  when: sshd_version.stdout >= '6.3' and not ssh_host_key_files
-
-- name: set hostkeys according to openssh-version
-  set_fact:
-    ssh_host_key_files: ['/etc/ssh/ssh_host_rsa_key', '/etc/ssh/ssh_host_ecdsa_key']
-  when: sshd_version.stdout >= '6.0' and not ssh_host_key_files
-
-- name: set hostkeys according to openssh-version
-  set_fact:
-    ssh_host_key_files: ['/etc/ssh/ssh_host_rsa_key']
-  when: sshd_version.stdout >= '5.3' and not ssh_host_key_files
+- include: crypto.yml
 
 - name: create revoked_keys and set permissions to root/600
   template: src='revoked_keys.j2' dest='/etc/ssh/revoked_keys' mode=0600 owner="{{ ssh_owner }}" group="{{ ssh_group }}"

diff --git a/templates/openssh.conf.j2 b/templates/openssh.conf.j2
@@ -45,68 +45,34 @@ CheckHostIP yes
 # Always ask before adding keys to the `known_hosts` file. Do not set to `yes`.
 StrictHostKeyChecking ask
 
+
 # **Ciphers** -- If your clients don't support CTR (eg older versions), cbc will be added
 # CBC: is true if you want to connect with OpenSSL-base libraries
 # eg ruby Net::SSH::Transport::CipherFactory requires cbc-versions of the given openssh ciphers to work
 # -- see: (http://net-ssh.github.com/net-ssh/classes/Net/SSH/Transport/CipherFactory.html)
 #
-{% if ssh_client_cbc_required -%}
-    {% if (ansible_distribution == 'Ubuntu' and ansible_distribution_version >= '14.04') or (ansible_distribution == 'Debian' and ansible_distribution_version >= '8') or (ansible_os_family in ['Oracle Linux', 'RedHat'] and ansible_distribution_major_version >= '7') or (ansible_distribution == 'FreeBSD' and ansible_distribution_version >= '11') -%}
-    Ciphers {{ ssh_ciphers_66_weak | join(',') }}
-    {% else -%}
-    Ciphers {{ ssh_ciphers_53_weak | join(',') }}
-    {% endif %}
-{% else -%}
-    {% if (ansible_distribution == 'Ubuntu' and ansible_distribution_version >= '14.04') or (ansible_distribution == 'Debian' and ansible_distribution_version >= '8') or (ansible_os_family in ['Oracle Linux', 'RedHat'] and ansible_distribution_major_version >= '7') or (ansible_distribution == 'FreeBSD' and ansible_distribution_version >= '11') -%}
-        Ciphers {{ ssh_ciphers_66_default | join(',') }}
-    {% else -%}
-        Ciphers {{ ssh_ciphers_53_default | join(',') }}
-    {% endif %}
-{% endif %}
+
+{# This outputs "Ciphers <list-of-ciphers>" if ssh_ciphers is defined or "#Ciphers" if ssh_ciphers is undefined #}
+{{ "Ciphers "+ssh_ciphers| join(',') if ssh_ciphers else "Ciphers"|comment }}
 
 # **Hash algorithms** -- Make sure not to use SHA1 for hashing, unless it is really necessary.
 # Weak HMAC is sometimes required if older package versions are used
 # eg Ruby's Net::SSH at around 2.2.* doesn't support sha2 for hmac, so this will have to be set true in this case.
 #
-{% if ssh_client_weak_hmac -%}
-    {% if (ansible_distribution == 'Ubuntu' and ansible_distribution_version >= '14.04') or (ansible_distribution == 'Debian' and ansible_distribution_version >= '8') or (ansible_os_family in ['Oracle Linux', 'RedHat'] and ansible_distribution_major_version >= '7') or (ansible_distribution == 'FreeBSD' and ansible_distribution_version >= '11') -%}
-        MACs {{ ssh_macs_66_weak | join(',') }}
-    {% elif ansible_os_family in ['Oracle Linux', 'RedHat'] and ansible_distribution_major_version <= '6' -%}
-    MACs {{ ssh_macs_53_default | join(',') }}
-    {% endif %}
-{% else -%}
-    {% if (ansible_distribution == 'Ubuntu' and ansible_distribution_version >= '14.04') or (ansible_distribution == 'Debian' and ansible_distribution_version >= '8') or (ansible_os_family in ['Oracle Linux', 'RedHat'] and ansible_distribution_major_version >= '7') or (ansible_distribution == 'FreeBSD' and ansible_distribution_version >= '11') -%}
-    MACs {{ ssh_macs_66_default | join(',') }}
-    {% elif ansible_os_family in ['Oracle Linux', 'RedHat'] and ansible_distribution_major_version <= '6' -%}
-        MACs {{ ssh_macs_53_default | join(',') }}
-    {% else -%}
-        MACs {{ ssh_macs_59_default | join(',') }}
-    {% endif %}
-{% endif %}
+
+{# This outputs "MACs <list-of-macs>" if ssh_macs is defined or "#MACs" if ssh_macs is undefined #}
+{{ "MACs "+ssh_macs| join(',') if ssh_macs else "MACs"|comment }}
 
 # Alternative setting, if OpenSSH version is below v5.9
 #MACs hmac-ripemd160
 
 # **Key Exchange Algorithms** -- Make sure not to use SHA1 for kex, unless it is really necessary
 # Weak kex is sometimes required if older package versions are used
 # eg ruby's Net::SSH at around 2.2.* doesn't support sha2 for kex, so this will have to be set true in this case.
-#
-{% if (ansible_distribution == 'Ubuntu' and ansible_distribution_version >= '14.04') or (ansible_distribution == 'Debian' and ansible_distribution_version >= '8') or (ansible_os_family in ['Oracle Linux', 'RedHat'] and ansible_distribution_major_version >= '7') or (ansible_distribution == 'FreeBSD' and ansible_distribution_version >= '11') -%}
-   {% if ssh_client_weak_kex -%}
-    KexAlgorithms {{ ssh_kex_66_weak | join(',') }}
-   {% else -%}
-        KexAlgorithms {{ ssh_kex_66_default | join(',') }}
-   {% endif %}
-{% else -%}
-   {% if ansible_os_family in ['Oracle Linux', 'RedHat'] and ansible_distribution_major_version <= '6' -%}
-           #KexAlgorithms
-   {% elif ssh_client_weak_kex -%}
-           KexAlgorithms {{ ssh_kex_59_weak | join(',') }}
-   {% else -%}
-           KexAlgorithms {{ ssh_kex_59_default | join(',') }}
-   {% endif %}
-{% endif %}
+# based on: https://bettercrypto.org/static/applied-crypto-hardening.pdf
 
+{# This outputs "KexAlgorithms <list-of-algos>" if ssh_kex is defined or "#KexAlgorithms" if ssh_kex is undefined #}
+{{ "KexAlgorithms "+ssh_kex| join(',') if ssh_kex else "KexAlgorithms"|comment }}
 
 # Disable agent forwarding, since local agent could be accessed through forwarded connection.
 ForwardAgent no