Security: Add tasks for RHEL-07-010020

This patch adds tasks which check for files that have been modified
since their packages were installed. This can sometimes be sign
of compromise.

Any files failing checksum validation are displayed for the deployer
to review.

Implements: blueprint security-rhel7-stig
Change-Id: I5ccc375ecb08e51c51dab80b47a190050731f700

doc/metadata/rhel7/RHEL-07-010020.rst

@@ -1,7 +1,17 @@
 ---
 id: RHEL-07-010020
-status: not implemented
-tag: misc
+status: implemented
+tag: packages
 ---
 
-This STIG requirement is not yet implemented.
+Ansible tasks will check the ``rpm -Va`` output (on CentOS and RHEL) or the
+output of ``debsums`` (on Ubuntu) to see if any files installed from packages
+have been altered.  The tasks will print a list of files that have changed
+since their package was installed.
+
+Deployers should be most concerned with any checksum failures for binaries and
+their libraries. These are most often a sign of system compromise or poor
+system administration practices.
+
+Configuration files may appear in the list as well, but these are often less
+concerning since some of these files are adjusted by the security role itself.

tasks/rhel7stig/apt.yml

@@ -0,0 +1,62 @@
+---
+# Copyright 2016, Rackspace US, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+- name: Ensure debsums is installed
+  apt:
+    name: debsums
+    state: installed
+
+- name: Gather debsums report
+  shell: "debsums > {{ temp_dir }}/debsums.txt"
+  changed_when: False
+  failed_when: False
+  when:
+    - not check_mode | bool
+
+- name: RHEL-07-010020 - Get files with invalid checksums (apt)
+  shell: "grep -v OK$ {{ temp_dir }}/debsums.txt | awk '{ print $1 }'"
+  register: rhel_07_010020_files
+  changed_when: False
+  when:
+    - not check_mode | bool
+    - ansible_os_family | lower == 'debian'
+  tags:
+    - high
+    - RHEL-07-010020
+
+- name: RHEL-07-010020 - Create comma-separated list
+  set_fact:
+    rhel_07_010020_violations: "{{ rhel_07_010020_files.stdout_lines | default([]) | join(', ') }}"
+  when:
+    - rhel_07_010020_files is defined
+    - rhel_07_010020_files.stdout_lines | length > 0
+  tags:
+    - high
+    - RHEL-07-010020
+
+- name: RHEL-07-010020 - The cryptographic hash of system files and commands must match vendor values (apt)
+  debug:
+    msg: >
+      The following files have checksums that differ from the checksum provided
+      with their package. Each of these should be verified manually to ensure
+      they have not been modified by an unauthorized user:
+      {{ rhel_07_010020_violations }}
+  when:
+    - ansible_os_family | lower == 'debian'
+    - rhel_07_010020_files is defined
+    - rhel_07_010020_files.stdout_lines | length > 0
+  tags:
+    - high
+    - RHEL-07-010020

tasks/rhel7stig/main.yml

@@ -42,10 +42,22 @@
     - always
     - skip_ansible_lint
 
+- include: apt.yml
+  when:
+    - ansible_os_family | lower == 'debian'
+  tags:
+    - apt
+
 - include: file_perms.yml
   tags:
     - file_perms
 
+- include: rpm.yml
+  when:
+    - ansible_os_family | lower == 'redhat'
+  tags:
+    - rpm
+
 - name: Remove the temporary directory
   file:
     path: "{{ temp_dir }}"

tasks/rhel7stig/rpm.yml

@@ -0,0 +1,44 @@
+---
+# Copyright 2016, Rackspace US, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+- name: RHEL-07-010020 - Get files with invalid checksums (rpm)
+  shell: "grep '^..5' {{ temp_dir }}/rpmverify.txt | awk '{ print $NF }'"
+  register: rhel_07_010020_files
+  changed_when: False
+  when:
+    - not check_mode | bool
+    - ansible_os_family | lower == 'redhat'
+  tags:
+    - high
+    - RHEL-07-010020
+
+- name: RHEL-07-010020 - The cryptographic hash of system files and commands must match vendor values (rpm)
+  debug:
+    msg: |
+      The following files have checksums that differ from the checksum provided
+      with their package. Each of these should be verified manually to ensure
+      they have not been modified by an unauthorized user.
+
+      {% for filename in rhel_07_010020_files.stdout_lines %}
+        {{ filename }}
+      {% endfor %}
+  when:
+    - not check_mode | bool
+    - ansible_os_family | lower == 'redhat'
+    - rhel_07_010020_files is defined
+    - rhel_07_010020_files.stdout_lines | length > 0
+  tags:
+    - high
+    - RHEL-07-010020