STIG-Partitioned Enterprise Linux (spel) is a project that helps create and
publish Enterprise Linux images that are partitioned according to the
DISA STIG. The resulting images also use LVM to simplify volume management.
The images are configured with help from the scripts and packages in the
AMIgen7, AMIgen8, and AMIgen9 projects1.
Notes on Lifecycle:
- Images are released on a monthly cadence. This cadence ensures that, if a user launches a brand new instance from the most-recently published AMI, that there will be less than a month's worth of system-patches to apply as part of the system-owner's system-provisioning processes.
- "Free" Enterprise Linux distributions are configured to use the public repositories offered by the distribution-owner. If running EC2s inside of a VPC with no access to the internet at large, it will not be possible to install additional RPMs or patch systems without the use of either a proxy or standing up a private yum mirror
- Red Hat images are configured to use a given cloud service provider's (CSP) Red Hat Update Infrastructure (a.k.a., "RHUI") repositories. These repositories are managed by Red Hat engineers and provide local RPM update-service within each CSP-partner's networks. Unlike RPM-access via RHN or Satellite, RHUI access is tied to and paid for via your CSP's billing-mechanisms. RHUI access also entitles cloud-VMs' owners to limited operating system support through the respective CSP's support channels.
- AWS Specific notes:
-
Access to the RHUI repositories is gated, in part, by an attribute attached to EC2s. This attribute is inherited from their corresponding AMIs. To view this attribute external to the EC2, execute:
aws ec2 describe-instances --query 'Reservations[].Instances[].UsageOperation' --instance-idsThis should return a value of
RunInstances:0010. If the value is justRunInstancesthe necessary attribute is missing from the EC2.The attribute may also be viewed internal to the EC2 by executing:
curl http://169.254.169.254/latest/dynamic/instance-identity/document | \ grep "billingProducts"This should return a value of
"billingProducts" : [ "bp-6fa54006" ]. If not, the necessary attribute is missing from the EC2.In either case, lack of the requisite attribute will mean that attempts to install or update RPMs from RHUI will fail.
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If patch-updates should come from RHN, Satellite or other private repository, do not use the AMIs published by the maintainers of this project. Because the previously-mentioned EC2-attribute is attached to such AMIs, you will be billed for the RHUI access even if you never use it. Feel free to use this project's code to generate your own, unencumbered AMIs.
-
Further information about AWS polices for Red Hat EC2s may be found in AWS's RHEL FAQ
-
VMs' root filesystems are generally not live-repartitionable once launced from
their images. As a result, if a STIG-scan is performed against most of the
community-published images for Red Hat and related distros (CentOS/CentOS
Stream, Oracle Linux, Rocky, Alma or Liberty), those
scans will note failures for each of the various "${DIRECTORY} is on its own
filesystem" tests. The images produced through this project are designed to
ensure that these particular scan-failures do not occur.
Aside from addressing the previously-noted partitioning findings, spel applies only those STIG-related hardenings that need to be in place "from birth" (i.e., when a system is first created from KickStart, VM-template, Amazon Machine Image, etc.). This includes things like:
- Activation of SELinux
- Application of SELinux user-confinement to the default-user2
- Application of SELinux role-transition rules for the default-user
- Activation of FIPS mode
- Support for BIOS- and/or EFI-boot modes (the latter being a requisite for use of SecureBoot)
The spel-produced images are expected to act as a better starting-point in a larger hardening process.
If your organization does not already have an automated hardening process, please see our tool, Watchmaker. This tool is meant to help spel-users (and users of other Enterprise Linux images) by performing launch-time hardening activities.
We've added an FAQ to the project. Hopefully, your questions are answered there. If they aren't, please feel free to submit an issue requesting an appropriate FAQ entry.
SPEL AMIs are published monthly. The AMI table below contains links to the AWS Console that search by AMI Name and sort the result by creation date. The most recent AMI of each build will be at the top when viewed in the AWS Console.
RPM Manifests for published images are available in the manifests directory.
Please note: the RPM-manifests published to this directory are generated for the AWS (CONUS) commercial regions. Due to potential deltas between the repositories used for the commercial and govcloud regions, there may also exist deltas between what is found in the manifests in this project and the version-numbers found in the GovCloud region AMIs.
| Vagrant Cloud Name | Vagrant Provider |
|---|---|
| plus3it/spel-minimal-centos-9stream | virtualbox |
The following table lists the official owner accounts for the images.
| AWS Partition | Account ID | Effective Release |
|---|---|---|
| aws | 174003430611 | 2023.08.1 and later |
| aws-us-gov | 216406534498 | 2023.08.1 and later |
The following table lists AWS account IDs previously used to host SPEL images. These accounts are now closed, and the associated images are no longer available.
| AWS Partition | Account ID | Effective Release |
|---|---|---|
| aws | 701759196663 | 2023.07.1 and earlier |
| aws-us-gov | 039368651566 | 2023.07.1 and earlier |
Deprecated Images have become end-of-life and no longer have available yum repos. The images remain public until the image deprecation period expires, typically 1 year after publishing.
| Vagrant Cloud Name | Vagrant Provider |
|---|---|
| plus3it/spel-minimal-centos-7 | virtualbox |
The default username for all spel images is maintuser.
If you wish to change the default username at launch, you can do so via
cloud-init with userdata3 something like the following. Change <USERNAME> to
your desired value.
#cloud-config
system_info:
default_user:
name: <USERNAME>
gecos: spel default user
lock_passwd: trueDue to updates to the STIGs – currently just for EL7, but it is assumed
that similar changes for EL8 and later distros will be added to future
STIG-releases – the default-user's account may have additional SELinux
rules applied to it. These rules will typically manifest in processes that
start as the default-user (i.e., processes run as the root user after
privilege-escalation via the sudo subsystem) receiving permission denied
errors when attempting to access "sensitive" files. These "sensitive" files
are any that have the shadow_t SELinux context-label applied to them. By
default, these will only include:
- /etc/security/opasswd
- /etc/shadow
- /etc/gshadow
A definitive list may be gathered by executing the command:
find / -context "*shadow_t*"`
If your workflows absolutely require the ability to access these files after
a role-transition from the default-user account to root, it will be necessary
to update the userData payload's cloud-config content to include a block
similar to:
#cloud-config
system_info:
default_user:
name: <USERNAME>
gecos: spel default user
lock_passwd: true
selinux_user: unconfined_u
sudo: ["ALL=(root) NOPASSWD:ALL"]However, doing so will result in security scan-failures when the scanning-tool tries to ensure that all locally-managed, interactive users are properly-constrained users and, where appropriate, have SELinux privilege-transition rules defined.
Packer by Hashicorp is used to manage the process of building
images.
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Download and extract
packerfor your platform. Add it to your PATH, if you like. On Linux, watch out for otherpackerexecutables with the same name (if building from an Enterprise Linux distro,/sbin/packermay be present due to thecracklib-dictsRPM). -
If building AMIs for Amazon Web Services, ensure your AWS credentials are configured. You do not really need the
awscli utility, but it is a convenient way to configure the credential file. You can also export the environment variables. Or, if runningpackerin an EC2 instance, an instance role with the requisite permissions will also work. See thepackerdocs for details on the necessary permissions.NOTE: No packer templates in this project will contain variables for AWS credentials; this is intentional, to avoid mistakes where credentials get committed to the repository. Instead,
packerknows to read the credentials from the credential file or from the environment variables, or to retrieve them from the instance role. See the docs. -
If building VirtualBox image(s), you will need to install VirtualBox and Vagrant.
-
If building VMware image(s), depending on your platform, you will need to install either VMware Fusion, VMware Workstation Pro, or VMware Player. For all platforms, you will also need Vagrant.
-
The template(s) push the Vagrant boxes for the VirtualBox and VMware images to Hashicorp Vagrant Cloud, which requires a Vagrant Cloud account.
-
If building a VHD or Image for Azure, ensure you have authorized access to ARM. The creation of destination objects and a Service Principal can either be done manually or via script. If not building in Public region, use of device login is not possible and a Service Principal is required.
NOTE: In all steps below, the examples use syntax that works on Linux. If you
are running packer from a Windows system, simply use the appropriate syntax
for the relative path to the packer template. Most important, for Windows,
use .\ preceding the path to the template. E.g.
.\spel\minimal-linux.json.
-
Clone the repository:
git clone https://github.com/plus3it/spel && cd spel
-
Validate the template (Optional):
packer validate spel/minimal-linux.pkr.hcl
The project-included Packer HCL files have been pre-validated. If you encounter validation-errors with the included HCL files, it means that you're using a newer Packer version than the project has been tested against. Please open an issue to report the problem, ensuring to include the Packer version you were using when you encountered the problem.
-
Begin the build. This requires at least two variables,
spel_identifierandspel_version. See the section Packer Variables for more details.packer build \ -var 'spel_identifier=unique-project-id' \ -var 'spel_version=dev001' \ -var 'virtualbox_vagrantcloud_username=myvagrantclouduser' \ spel/minimal-linux.pkr.hclNOTE: This will build images for all the builders defined in the template. Use
packer build --helpto see how to restrict the build to to a subset of the builders using the-onlyor-exceptarguments.If building the VirtualBox or VMware images for use with Vagrant, the template is configured to host the resulting images with Hashicorp Vagrant Cloud. This requires passing the variable
virtualbox_vagrantcloud_usernameand exporting the environment variableVAGRANT_CLOUD_TOKEN.
The Minimal Linux template builds STIG-partitioned images with a set of
packages that correspond to the "Minimal" install option in Anaconda. Further,
the AWS images include a handful of additional packages that are intended to
increase functionality in EC2 and make the images more comparable with Amazon
Linux. Similarly, the Azure builder will attempt to install the WALinuxAgent
RPM into the VM-template to make the template more integratable into
Azure-based deployments.
- Template Path:
spel/minimal-linux.pkr.hcl
For all inputs to the template, see spel/README.md
The Minimal Linux packer template includes the following builders:
| Builder Name | Description |
|---|---|
amazon-ebssurrogate.minimal-centos-9stream-hvm |
amazon-ebs builder for a minimal CentOS Stream 9 HVM AMI |
amazon-ebssurrogate.minimal-ol-9-hvm |
amazon-ebs builder for a minimal Oracle Linux 9 HVM AMI |
amazon-ebssurrogate.minimal-rhel-9-hvm |
amazon-ebs builder for a minimal RHEL 9 HVM AMI |
amazon-ebssurrogate.minimal-ol-8-hvm |
amazon-ebs builder for a minimal Oracle Linux 8 HVM AMI |
amazon-ebssurrogate.minimal-rhel-8-hvm |
amazon-ebs builder for a minimal RHEL 8 HVM AMI |
virtualbox-iso.minimal-centos-9stream-image |
virtualbox-iso builder for a minimal CentOS Stream 9 Vagrant Box |
The Minimal Linux packer template includes the following post-provisioners:
-
vagrant: The vagrant post-provisioner creates vagrant boxes from on thevirtualboxandvmwareimages. -
vagrant-cloud: The vagrant-cloud post-provisioners upload the vagrant boxes to Hashicorp Vagrant Cloud.
To build images for the AWS US GovCloud regions, us-gov-west-1 or us-gov-east-1,
it is necessary to pass several variables that are specific to the region. The
AMI filters below have been tested and/or created in us-gov-west-1 to work with the
spel template(s). Also, the builders should be restricted so as not to build
the Vagrant images.
packer build \
-var 'spel_identifier=unique-project-id' \
-var 'spel_version=dev001' \
-var 'aws_region=us-gov-west-1' \
-exclude 'virtualbox-iso.*' \
spel/minimal-linux.pkr.hclA source Marketplace Image Offer or Custom Image Name and Resource Group are required from which to start the SPEL Azure build.
The resultant SPEL Image will be configured to use the Azure Linux agent, WALinuxAgent
per recommended configurations. Currently, the use of cloud-init exclusively
does not enable execution/installation of Azure VM Extensions. The below
variables also disable FIPS mode in the resultant SPEL VHD or Image. Currently,
the Azure Linux agent does not support FIPS mode when utilizing Azure VM
Extensions. If no plans exist to utilize Azure VM Extensions on VMs provisioned
from SPEL VHDs or Images, FIPS mode can be enabled, but the waagent configuration
must also be modified accordingly.
The variables referenced in the packer builds below should be modified with appropriate parameters for your environment. Any content between and including the < and > characters should be replaced.
Login to azure using the az cli. Packer will use the session setup by the az cli.
packer build \
-var 'spel_identifier=unique-project-id' \
-var 'spel_version=0.0.1' \
-var 'amigen_extra_rpms=["WALinuxAgent"]' \
-var 'amigen_fips_disable=true' \
-var 'amigen8_repo_names=["rhui-microsoft-azure-rhel8"]' \
-var 'azure_image_offer=rhel-raw' \
-var 'azure_image_publisher=RedHat' \
-var 'azure_image_sku=8_8' \
-var 'azure_managed_image_resource_group_name=<resource group short name>' \
-only 'azure-arm.minimal-rhel-8-image' \
spel/minimal-linux.pkr.hclTo build images for an OpenStack environment, it is necessary to pass several variables that are specific to the environment. Also, the builders should be restricted so as not to build the Vagrant images.
source your_openstack_credentials_file.sh
packer build \
-var 'spel_identifier=spel' \
-var 'spel_version=0.0.1' \
-var 'openstack_insecure=false' \
-var 'openstack_flavor=your_flavor_name_for_temporary_instance' \
-var 'openstack_floating_ip_network=your_provider_network_name' \
-var 'openstack_networks=your_network_id_for_temporary_instance,second_network_id,etc.' \
-var 'openstack_security_groups=your_security_group_name_for_temporary_instance,second_sg_name,etc.' \
-var 'openstack_source_image_name=your_source_image_name' \
-only 'openstack.*' \
spel/minimal-linux.pkr.hclFor expected values, see links below:
- openstack_allow_insecure (true|false)
- openstack_flavor_name (string)
- openstack_floating_ip_network_name (string)
- openstack_network_ids (comma-separated list of strings)
- openstack_security_group_names (comma-separated list of strings)
- openstack_source_image_name (string)
The spel automation leverages the AMIgen8 and AMIgen9 projects as a build-helpers for creation of EL8 and EL9 Amazon Machine Images (Azure VM-templates, etc.), respectively. Due to the closely-coupled nature of the two projects, it's recommended that any changes made to AMIgen8 or AMIgen9 be tested with spel prior to merging changes to either project's master branch.
To facilitate this testing, the following runtime-variables were added to spel:
amigen8_source_branchamigen8_source_urlamigen9_source_branchamigen9_source_url
Using these runtime-variables allows one to point spel to
a fork/branch of AMIgen8 or AMIgen9 during a integration-test build. To test,
update your packer invocation by adding elements like:
packer build \
-var 'amigen8_source_url=https://github.com/<FORK_USER>/AMIgen8.git' \
-var 'amigen8_source_branch=IssueNN' \
...
minimal-linux.pkr.hclSimilarly, these variables may be specified as environment variables by using PKR_VAR_<var_name>
declarations4 (e.g., PKR_VAR_amigen8_source_branch). To do so, change the
above example to:
export PKR_VAR_amigen8_source_branch="=https://github.com/<FORK_USER>/AMIgen8.git"
export PKR_VAR_amigen8_source_branch="IssueNN"
packer build \
[...options elided...]
minimal-linux.pkr.hclFootnotes
-
Because spel is primarily an execution-wrapper for the AMIgenN projects, the "read the source" method for determining why things have changed from one spel-release to the next may require reviewing those projects' repositories ↩
-
The default-user is a local user (i.e., managed in
/etc/passwd//etc/shadow//etc/group) that is dynamically-created at initial system-boot – using either the default-information in the/etc/cloud/cloud.cfgfile or as overridden in a userData payload's#cloud-configcontent. Typically this user's${HOME}/.ssh/authorized_keysfile is prepopulated with a provisioner's public SSH key. ↩ -
Overriding attributes of the default-user must be done within a
#cloud-configdirective-block. If your userData is currently bare BASH (etc.), it will be necessary to format your userData payload as mixed, multi-part MIME. ↩ -
Use of the
PKR_VAR_method is recommended for setting up CI/CD frameworks for producing AMIs and other supported VM-templates ↩