Microsoft Windows PAW Security Technical Implementation Guide

The AO must designate which IT resources are high value. The list must include the following IT resources: - Directory service (including Active Directory) - Cloud service - Identity management service - Privileged access management service - Credential management service - Security management service (anti-virus, network monitoring/scanning, IDS/IPS, etc.) - Any sensitive business/mission service - Any other IT resource designated as high value by the AO Note: A high-value IT resource is defined as any IT resource whose purpose is considered critical to the organization or whose loss or compromise would cause a significant impact on the organization. Note: Sensitive business/mission service is any business or mission service that needs additional protection from higher-risk IT services based on the nature of the function it provides; sensitivity of the data it consumes, processes, or stores; or criticality to the operation of the organization. High-value IT resources are the most important and critical IT resources within an organization. They contain the most sensitive data in an organization, perform the most critical tasks of an organization, or have access to and can control all or nearly all IT resources within an organization. Administrator accounts for high-value IT resources must be protected against various threats and attacks because threats to sensitive privileged accounts are high and risk of compromise is increasing. Requiring a PAW used exclusively for remote administrative management of designated high-value IT resources, including servers, workstations, directory services, applications, databases, and network components, will provide a separate "channel" for the performance of administrative tasks on high-value IT resources and isolate these functions from the majority of threats and attack vectors found on higher-risk standard client systems. Some IT resources, by the nature of the function they perform, should always be considered high value and should be remotely administered only via a PAW. The IT resources listed above are in this category. Note: The term "manage" in the Requirement statement includes any remote connection to a high-value IT resource (for example, to view resource status and current configuration or to make changes to any resource configuration).

Note: The Microsoft Tier 0-2 AD administrative tier model (https://docs.microsoft.com/en-us/windows-server/identity/securing-privileged-access/securing-privileged-access-reference-material#ADATM_BM) is an example. A key security construct of a PAW is to separate administrative accounts into specific trust levels so that an administrator account used to manage an IT resource at one trust level cannot be used to manage IT resources at another trust level. This architecture protects IT resources in a tier from threats from higher-risk tiers. Isolating administrative accounts by forcing them to operate only within their assigned trust zone implements the concept of containment of security risks and adversaries within a specific zone. The Tier model prevents escalation of privilege by restricting what administrators can control and where they can log on.

Note: Allowed exception - For sites that are constrained in the number of available workstations, an acceptable approach is to install lower-tier administrative accounts on a separate virtual machine (VM) on the PAW workstation where higher-tier administrative accounts are installed on the host OS and lower-tier administrative accounts are installed in a VM. The VM will provide acceptable isolation between administrative accounts of different tiers. Note: Relationship between the exception in WPAW-00-000500 and WPAW-00-001000 and requirement WPAW-00-001800: WPAW-00-000500 and WPAW-00-001000 allow an exception to the requirement for sites constrained in the number of available workstations. Lower-tier, high-value admin accounts can operate in a VM if the higher-tier, high-value admin accounts operate in the VM host-OS, but WPAW-00-001800 is more appropriate for a multiple PAW VM environment. If administrative accounts assigned to different tiers were installed on the same PAW, it would be impossible to isolate administrative accounts to specific trust zones and protect IT resources from one trust zone (tier) from threats from high-risk trust zones.

Note: The Microsoft Tier 0-2 AD administrative tier model (https://docs.microsoft.com/en-us/windows-server/identity/securing-privileged-access/securing-privileged-access-reference-material#ADATM_BM) is an example. A key security construct of a PAW is to separate high-value IT resources into specific trust levels so that if a device at one trust level is compromised the risk of compromise of more critical IT resources at a different tier is reduced. This architecture protects IT resources in a tier from threats from higher-risk tiers. Isolating administrative accounts by forcing them to operate only within their assigned trust zone implements the concept of containment of security risks and adversaries within a specific zone.

Older versions of operating systems usually contain vulnerabilities that have been fixed in later released versions. In addition, most operating system patches contain fixes for recently discovered security vulnerabilities. Due to the highly privileged activities of a PAW, it must be maintained at the highest security posture possible and therefore must have one of the current vendor-supported operating system versions installed.

Older versions of operating systems usually contain vulnerabilities that have been fixed in later versions. In addition, most operating system patches contain fixes for recently discovered security vulnerabilities. Due to the highly privileged activities of a PAW, it must be maintained at the highest security posture possible and therefore must have the latest operating system updates installed. Because a PAW is isolated from online operating system update services, a software update service must be available on the intranet to manage operating system and other software updates for site PAWs. A separate software update service is not required at each tier.

Note: The intent of this requirement is that a PAW must not be used for any function not related to the management of high-value IT resources. Note: Authorized exception - It is noted that administrators will need access to non-administrative functions, such as email and the Internet, but a PAW must not be used for these activities. For sites that are constrained in the number of available workstations, an acceptable approach is to install the non-administrative services on a separate virtual machine (VM) on the workstation where the PAW service is installed. The VM will provide acceptable isolation between high-value administrative management accounts and non-administrative services. Note: Relationship between the exception in WPAW-00-000500 and WPAW-00-001000 and requirement WPAW-00-001800: WPAW-00-000500 and WPAW-00-001000 allow an exception to the requirement for sites constrained in the number of available workstations. Lower-tier, high-value admin accounts can operate in a VM if the higher-tier, high-value admin accounts operate in the VM host-OS, but WPAW-00-001800 is more appropriate for a multiple PAW VM environment. A main security architectural construct of a PAW is to remove non-administrative applications and functions from the PAW workstation. Many standard user applications and functions, including email processing, Internet browsing, and using business applications, can increase the security risk to the workstation. These apps and functions are susceptible to many security vulnerabilities, including phishing attacks and embedded malware. This increased risk is not acceptable for the highly privileged activities of a PAW.

A main security architectural construct of a PAW is to restrict non-administrative applications and functions from the PAW workstation. Many standard user applications and functions, including email processing, Internet browsing, and using business applications, can increase the security risk to the workstation. These apps and functions are susceptible to many security vulnerabilities, including phishing attacks and embedded malware. This increased risk is not acceptable for the highly privileged activities of a PAW.

A main security architectural construct of a PAW is to restrict non-administrative applications and functions from the PAW workstation. Many standard user applications and functions, including email processing, Internet browsing, and using business applications, can increase the security risk to the workstation. These apps and functions are susceptible to many security vulnerabilities, including phishing attacks and embedded malware. This increased risk is not acceptable for the highly privileged activities of a PAW.

A main security architectural construct of a PAW is to limit users of the PAW to only administrators of high-value IT resources. This will mitigate some of the risk of attack on administrators of high-value IT resources.

If the domain is not configured to restrict privileged administrator accounts from logging on to lower-tier hosts, it would be impossible to isolate administrative accounts to specific trust zones and protect IT resources from threats from high-risk trust zones. Blocking logon to lower-tier assets helps protect IT resources in a tier from being attacked from a lower tier.

PAW platforms are used for highly privileged activities. The accounts that have administrative privileges on domain-level PAW platforms must not be used on or used to manage any non-domain-level PAW platforms. Otherwise, there would be a clear path for privilege escalation to Enterprise Admin (EA)/Domain Admin (DA) privileges.

Note: PAW accounts used to manage high-value IT resources have privileged rights on managed systems but no administrative or maintenance rights on the PAW. They only have user rights on the PAW. PAW administrative/maintenance accounts only have administrative rights on a PAW and are used only to perform administrative functions on the PAW. PAW administrative/maintenance accounts are the only admin accounts that have admin rights on a PAW. It is not required that PAW administrative/maintenance accounts be organized by tier. The PAW platform should be protected from high-value IT resource administrators accidently or deliberately modifying the security settings of the PAW. Therefore, high-value IT resource administrators must not have the ability to perform maintenance functions on the PAW platform. Separate PAW admin accounts must be set up that only have rights to manage PAW platforms. PAW administrators have the capability to compromise Domain Admin accounts; therefore, personnel assigned as PAW administrators must be the most trusted and experienced administrators within an organization, at least equal to personnel assigned as domain administrators.

Due to the highly privileged functions of a PAW, a high level of trust must be implemented for access to the PAW, including non-repudiation of the user session. One-factor authentication, including username and password and shared administrator accounts, does not provide adequate assurance.

A main security architectural construct of a PAW is to remove non-administrative functions from the PAW. Many standard user functions, including email processing, Internet browsing, and using business applications, can increase the security risk of the workstation. These apps and functions are susceptible to many security vulnerabilities, including phishing attacks and embedded malware. This increased risk is not acceptable for the highly privileged activities of a PAW. This requirement enforces this security concept in an environment where multiple PAW VMs are installed on a host server. Note: Relationship between the exception in WPAW-00-000500 and WPAW-00-001000 and requirement WPAW-00-001800: WPAW-00-000500 and WPAW-00-001000 allow an exception to the requirement for sites constrained in the number of available workstations. Lower-tier, high-value admin accounts can operate in a VM if the higher-tier, high-value admin accounts operate in the VM host-OS, but WPAW-00-001800 is more appropriate for a multiple PAW VM environment.

A main security architectural construct of a PAW is that the workstation is isolated from most Internet threats, including phishing, impersonation, and credential theft attacks. This isolation is partially implemented by blocking unsolicited inbound traffic to the PAW.

Note: Internal domain connections from a PAW to communicate with IT resources being managed via the PAW with domain controllers or with a digital credential verification service (for example, Online Certificate Status Protocol [OCSP]) are allowed. A main security architectural construct of a PAW is that the workstation is isolated from most internet threats, including phishing, impersonation, and credential theft attacks. This isolation is partially implemented by blocking all outbound connections to the internet.

A main security architectural construct of a PAW is to restrict access to the PAW from only specific privileged accounts designated for managing the high-value IT resources the PAW has been designated to manage. If unauthorized standard user accounts or unauthorized high-value administrative accounts are able to access a specific PAW, high-value IT resources and critical DoD information could be compromised.

A main security architectural construct of a PAW is to restrict access to the PAW from only specific privileged accounts designated for managing the high-value IT resources the PAW has been designated to manage. If unauthorized standard user accounts or unauthorized high-value administrative accounts are able to access a specific PAW, high-value IT resources and critical DoD information could be compromised.

Restricted remote administration features, RestrictedAdmin mode, and Remote Credential Guard for Remote Desktop Protocol (RDP), are an additional safeguard against "pass the hash" attacks, where hackers attempt to gain higher administrative privileges from a single compromised machine. Restricted remote administration protects administrator accounts by ensuring that reusable credentials are not stored in memory on remote devices that could potentially be compromised. When restricted remote administration is implemented, the local RDP service tries to log on to the remote device using a network logon, so the user's credentials are not sent across the network. Therefore, if the high-value IT resource is compromised, the credentials of the administrator connecting to the IT resource from the PAW are not compromised.

The VM host OS should be protected from high-value IT resource administrators accidently or deliberately modifying the security settings of the host OS. Therefore, high-value IT resource administrators must not have the ability to perform maintenance functions on the VM host OS platform.