os-hardening (Chef cookbook)

Description

This cookbook provides numerous security-related configurations, providing all-round base protection.

It configures:

• Configures package management e.g. allows only signed packages
• Remove packages with known issues
• Configures pam and pam_limits module
• Shadow password suite configuration
• Configures system path permissions
• Disable core dumps via soft limits
• Restrict Root Logins to System Console
• Set SUIDs
• Configures kernel parameters via sysctl

It will not:

• Update system packages
• Install security patches

Requirements

• Chef >= 12.5.1
• Cookbooks:
  • Sander van Zoest sysctl https://github.com/svanzoest-cookbooks/sysctl

Note for sysctl usage:

We deprecated sysctl version before 0.6.0. Future versions of this cookbook will depend on version 0.6.0 and greater. If you are going to use version 0.6.0, use sysctl::apply instead of sysctl::default in your runlist to ensure the configuration change will be applied.

Optional: you can use berkshelf to install dependencies.

Attributes

• ['os-hardening']['desktop']['enable'] = false true if this is a desktop system, ie Xorg, KDE/GNOME/Unity/etc
• ['os-hardening']['network']['forwarding'] = false true if this system requires packet forwarding (eg Router), false otherwise
• ['os-hardening']['network']['ipv6']['enable'] = false
• ['os-hardening']['network']['arp']['restricted'] = true true if you want the behavior of announcing and replying to ARP to be restricted, false otherwise
• ['os-hardening']['env']['extra_user_paths'] = [] add additional paths to the user's PATH variable (default is empty).
• ['os-hardening']['env']['umask'] = "027"
• ['os-hardening']['env']['root_path'] = "/" where root is mounted
• ['os-hardening']['auth']['pw_max_age'] = 60 maximum password age
• ['os-hardening']['auth']['pw_min_age'] = 7 minimum password age (before allowing any other password change)
• ['os-hardening']['auth']['pw_warn_age'] = 7 number of days before maximum password age occurs to warn of impending change
• ['os-hardening']['auth']['retries'] = 5 the maximum number of authentication attempts, before the account is locked for some time
• ['os-hardening']['auth']['lockout_time'] = 600 time in seconds that needs to pass, if the account was locked due to too many failed authentication attempts
• ['os-hardening']['auth']['timeout'] = 60 authentication timeout in seconds, so login will exit if this time passes
• ['os-hardening']['auth']['allow_homeless'] = false true if to allow users without home to login
• ['os-hardening']['auth']['pam']['passwdqc']['enable'] = true true if you want to use strong password checking in PAM using passwdqc
• ['os-hardening']['auth']['pam']['passwdqc']['options'] = "min=disabled,disabled,16,12,8" set to any option line (as a string) that you want to pass to passwdqc
• ['os-hardening']['security']['users']['allow'] = [] list of things, that a user is allowed to do. May contain: change_user
• ['os-hardening']['security']['kernel']['enable_module_loading'] = true true if you want to allowed to change kernel modules once the system is running (eg modprobe, rmmod)
• ['os-hardening']['security']['kernel']['enable_sysrq'] = false
• ['os-hardening']['security']['kernel']['enable_core_dump'] = false
• ['os-hardening']['security']['suid_sgid']['enforce'] = true true if you want to reduce SUID/SGID bits. There is already a list of items which are searched for configured, but you can also add your own
• ['os-hardening']['security']['suid_sgid']['blacklist'] = [] a list of paths which should have their SUID/SGID bits removed
• ['os-hardening']['security']['suid_sgid']['whitelist'] = [] a list of paths which should not have their SUID/SGID bits altered
• ['os-hardening']['security']['suid_sgid']['remove_from_unknown'] = false true if you want to remove SUID/SGID bits from any file, that is not explicitly configured in a blacklist. This will make every Chef run search through the mounted filesystems looking for SUID/SGID bits that are not configured in the default and user blacklist. If it finds an SUID/SGID bit, it will be removed, unless this file is in your whitelist.
• ['os-hardening']['security']['suid_sgid']['dry_run_on_unknown'] = false like remove_from_unknown above, only that SUID/SGID bits aren't removed. It will still search the filesystems to look for SUID/SGID bits but it will only print them in your log. This option is only ever recommended, when you first configure remove_from_unknown for SUID/SGID bits, so that you can see the files that are being changed and make adjustments to your whitelist and blacklist.
• ['os-hardening']['security']['packages']['clean'] = true removes packages with known issues.
• ['os-hardening']['security']['packages']['list'] = ['xinetd','inetd','ypserv','telnet-server','rsh-server'] list of packages to remove, by default we remove the following packages:
  • xinetd (NSA, Chapter 3.2.1)
  • inetd (NSA, Chapter 3.2.1)
  • tftp-server (NSA, Chapter 3.2.5)
  • ypserv (NSA, Chapter 3.2.4)
  • telnet-server (NSA, Chapter 3.2.2)
  • rsh-server (NSA, Chapter 3.2.3)

Usage

Add the recipes to the run_list, it should be last:

"recipe[os-hardening]"

Configure attributes:

"security" : {
  "kernel" : {
    "enable_module_loading" : true
  }
},

Local Testing

Local testing

Please install chef-dk, VirtualBox or VMware Workstation and Vagrant.

Linting is checked with rubocop and foodcritic:

$ chef exec rake lint
.....

Unit/spec tests are done with chefspec:

$ chef exec rake spec
.....

Integration tests are done with test-kitchen:

$ chef exec rake kitchen
.....
# or you can use the kitchen directly
$ kitchen test

CI testing of forks

You can enable testing of your fork in Travis CI. By default you will get linting and spec tests.

Integration tests of this repository are conducted using DigitalOcean.

If you want to have integration tests for your fork, you will have to add following environment variables in the settings of your fork:

• DIGITALOCEAN_ACCESS_TOKEN - access token for DigitalOcean
• CI_SSH_KEY - private part of some ssh key, available on DigitalOcean for your instances, in base64 encoded form (e.g. cat id_rsa | base64 -w0 ; echo)
• DIGITALOCEAN_SSH_KEY_IDS - ID in DigitalOcean of CI_SSH_KEY, see this for more information

Contributors + Kudos

• Dominik Richter arlimus
• Bernhard Weisshuhn bkw
• Christoph Hartmann chris-rock
• Edmund Haselwanter ehaselwanter
• Patrick Meier atomic111

This cookbook is mostly based on guides by:

• Arch Linux wiki, Sysctl hardening
• Ubuntu Security/Features
• NSA: Guide to the Secure Configuration of Red Hat Enterprise Linux 5
• Deutsche Telekom, Group IT Security, Security Requirements (German)

Thanks to all of you!!

Contributing

See contributor guideline.

License and Author

• Author:: Dominik Richter dominik.richter@googlemail.com
• Author:: Deutsche Telekom AG

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.