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Operating system patching and inventory guardrails for AWS

Maintaining up-to-date patch levels for cloud-based operating systems is a crucial security control for Enterprise organizations.

David Boeke
10 min. read - Apr 24, 2020
Maintaining up-to-date patch levels for cloud-based operating systems is a crucial security control for Enterprise organizations.

Capabilities

Patching and Patch Management

A key security control for Enterprise organizations is ensuring their fleet of cloud based operating systems maintain current patch levels. While the Enterprise probably has robust policies and capabilities in place for on premise patching, several cloud use-cases can challenge the assumptions those systems were built to solve:

  • Isolated networking: A common design pattern for cloud deployments is to fully isolate certain environments in their own private network. Without network connectivity to corporate systems, traditional capabilities for pushing patches will often be ineffective.
  • Auto-scaling and on-demand servers: One huge advantage of cloud is the ability to rapidly scale up and scale down computing resources to meet the workload demands of your application. This often creates challenges to standard practices of inventory management and patching at the enterprise level.
  • Capability Leapfrog: Too often on premise OS management and patching relies on manual work from managed service providers. Many Enterprises moving to the cloud are looking to automate these activities to achieve greater scalability, control and visibility to their security posture.

Turbot Guardrails Advantage

Turbot Guardrails provides a consistent hierarchal model to automate implementation and configuration of Amazon Systems Manager across all AWS accounts used by the enterprise. Through this automation, Turbot Guardrails enables inventory collection and patch management of your cloud environment, even when the instances are fully isolated from a networking perspective.

Targeting of Instances

Turbot Guardrails uses specially named tags to target instances for inventory collection and selection of maintenance windows.

  • Inventory collection enabled by the setting the instance tag
    • Tag Key: turbot:InventoryCollection
    • Tag Value: true
  • Patching is enabled by setting the instance tag:
    • Tag Key: turbot:PatchingMaintenanceWindow
    • Tag Value: (Maintenance Window)
  • The Patch Baseline is chosen via the optional SSM Patch Group tag
    • Tag Key: Patch Group
    • Tag Value: (Name of Patch Baseline)
    • Default: If not set the instance will be associated with the “Default” patch baseline.

SSM Specific Tagging Guardrails

AWS > EC2 > Instance Patch Management

  • Enabled with Target Patch Group Set ‘turbot:PatchingMaintenanceWindow’ and ‘Patch Group’ tags for an instance based on the value of ‘AWS > EC2 > Instance Patching Maintenance Window’ and AWS > EC2 > Instance Target Patch Group

AWS > EC2 > Instance Approved Patch Groups

  • YAML List A list of patch group names that are approved for use.

AWS > EC2 > Instance Target Patch Group

  • Text Value The patch group name that will be enforced as the Target patch group, or used as the initial patch group if enforcing with approved patch group. Must be part of the approved patch group list to be valid.

AWS > EC2 > Instance Patching Maintenance Window Text Value Set the maintenance window to be used for automatic patching. To be valid the Selected maintenance window must be defined in the policy SSM > Maintenance Window Definitions

AWS > EC2 > Instance Target Patch Group

  • Text Value The patch group name that will be enforced as the Target patch group, or used as the initial patch group if enforcing with approved patch group. Must be part of the approved patch group list to be valid.

AWS > EC2 > Inventory Collection for Bob's Demo Account

  • Enforce: Inventory collection enabled Apply the turbot:InventoryCollection tag to the instance and set the value to true.

Turbot Guardrails Tagging (optional):

Alternatively, you can use Turbot tagging guardrails to set tags on instances based on Account or instance level metadata. Please see /help/guides/tag-management/ on your Turbot Guardrails installation for detailed description of Turbot Guardrails tagging automation templates.

Patch Management Template Examples

Only do inventory collection on QA and Production accounts:

- turbot:InventoryCollection: "{% if TagsMap['Environment'] in [‘QA’,'Prod'] %}true{% else %}false{% endif %}"

Setting different patch maintenance windows for different environments:

- turbot:PatchingMaintenanceWindow: "{% if TagsMap['Environment'] in [‘QA’,'Prod'] %}MonthlyPatchWindow{% else %} WeeklyPatchWindow {% endif %}"

Systems Manager Setup

Instance Roles & Profiles

By default, Systems Manager doesn't have permission to perform actions on your instances. You must enable access by creating an IAM instance profile role, Turbot has Guardrails to automate this process for you:

Policies – Instance Roles Profiles & Policies

AWS > IAM > EC2 Role Has Turbot Guardrails Default Instance Policies

  • Enforce: Attach Turbot default instance policiesCheck that any role which can be attached to an EC2 instance has the Turbot EC2 Instance default policy attached to it. This allows dev teams to use their own instance profiles, but ensures that minimum access needed for SSM exists.

AWS > IAM > Turbot EC2 Instance Role

  • Enforce: Manage roleSet whether Turbot Guardrails should check if the Turbot EC2 instance role is configured correctly. Allows for override of default behavior for specifc account or instance level exceptions.

AWS > IAM > Turbot Maintenance Window Role

  • Enforce: Manage roleDetermines if Turbot Guardrails should check that the Turbot maintenance window role is configured correctly.

AWS > EC2 > Instance Has Default EC2 Instance Profile Attached Enforce: Attach default EC2 instance profile if no instance profile is attached Check if an EC2 instance has the default EC2 instance profile attached (as specified by EC2:DefaultEC2InstanceProfileName).

AWS > EC2 > Default EC2 Instance Profile Name

  • Text ValueThe name of the default instance profile to attached to EC2 instances. To use the Turbot Guardrails managed default role, set to ec2_instance_default.

AWS> SSM > Turbot EC2 Instance Role Permissions

  • Enabled if SSM > App EnabledInclude SSM permissions in Turbot default EC2 instance role permissions.

Install SSM Agent

Amazon Linux and AWS Windows AMIs have the Amazon SSM agent preinstalled. For other Linux OSs, Turbot Guardrails provides an automation (using an Ansible guardrail to install the SSM agent on those platforms).

Policies – SSM Agent

Linux > Install SSM Agent

  • EnabledInstall the SSM agent on instances launched with the Turbot Guardrails key pair. This will allow the instance to be managed by SSM.

SSM User Permissions and access

Your operation teams managing patching or your application teams (if patching is managed by the app teams) will need permissions to SSM to configure maintenance windows and view reports.

Policies – SSM Whitelisting

AWS> SSM > App Enabled

  • EnabledEnables SSM in the Service Whitelist.

AWS> SSM > Rights Enforce: Enabled if SSM > App Enabled Enables SSM Rights (allows owners to grant AWS/SSM level rights to Turbot Guardrails users).

SSM Maintenance Windows

Overview

By specifying maintenance windows in Turbot Guardrails, Turbot Guardrails will both ensure that the specified maintenance window is configured in AWS SSM an d that the maintenance window selected at the instance level is one of the approved maintenance windows.

Policies – Maintenance Window Configuration

Maintenance windows are defined with one policy and enforced with another.

AWS > SSM > Turbot Maintenance Window Definitions YAML Template Definition of the Turbot maintenance windows. Example:

-
  Name: Every8Hours
  Description: 'Turbot Every 8 Hours Maintenance Window'
  Schedule: 'cron(0 0 */8 * * ? *)'
  Duration: 4
  Cutoff: 1
  AllowUnassociatedTargets: false
-
  Name: Every30Mins
  Description: 'Turbot Every 30 mins Maintenance Window'
  Schedule: 'rate(30 minutes)'
  Duration: 1
  Cutoff: 0
  AllowUnassociatedTargets: false
-
  Name: Daily
  Description: 'Turbot Daily Maintenance Window'
  Schedule: 'cron(0 0 22 ? * * *)'
  Duration: 4
  Cutoff: 1
  AllowUnassociatedTargets: false
-
  Name: Weekly
  Description: 'Turbot Weekly Maintenance Window'
  Schedule: 'cron(0 0 22 ? * MON *)'
  Duration: 4
  Cutoff: 1
  AllowUnassociatedTargets: false

AWS > EC2 > Instance Patching Maintenance Window Text Value Set the maintenance window to be used for automatic patching. To be valid the Selected maintenance window must be defined in the policy SSM > Maintenance Window Definitions

AWS > EC2 > Turbot Maintenance Windows Enforce: Manage Turbot maintenance windows Set whether Turbot Guardrails should check if the Turbot maintenance windows are configured correctly.

Enabling Patch Management Feature in Turbot Guardrails

Patch management is released as a Preview feature in Turbot Guardrails(version 2.4). While in the preview stage, customers will have to specifically enable the feature by enabling the feature flag Parameter in the Turbot Guardrails Console CloudFormation script.

To do this a cloud admin (with appropriate permissions) will need to login to the Turbot Guardrails Master AWS account, navigate to the CloudFormation and select the current Turbot Guardrails Console CF script and choose Actions > Update Stack.

On the Parameter configuration page, add “PatchManagement” to the list of flags enabled. Add the flag without quotes and make sure to use commas to delimit the flag from other flags that may be enabled.

Continue the update of the stack (just like a standard Turbot Guardrails update process). When the script runs, Turbot Guardrails will start a rolling update of your cluster, at the end of that process, the feature and associated options will be enabled in your cluster. (Please note, due to browser caching, you may need to do a hard refresh of Turbot Guardrails in your browser window for the new options to appear.)

Patching Configuration in Turbot Guardrails

Turbot Guardrails recommends creating a default patching resource group that creates common patching requirements, and attaching that to the cluster level. This will ensure that new accounts adopt a baseline patching standard from the start.

Specific resource groups for common patching design patterns can then be created and set at the account level or the instance level:

  • Production Accounts (Monthly)
  • Non-Prod Accounts (Weekly)
  • No Patch / Manual Patching

If you need any assistance, let us know in our Slack community #guardrails channel. If you are new to Turbot, connect with us to learn more!