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Windows Server 2019 has brought in many enhancements to their security posture as well as a whole new set of capabilities. In one of the sessions titled ‘Elevating your security posture with Windows Server 2019’ at Microsoft Ignite 2018, Dean Wells, a program manager in the Windows Server team, provided a rich overview of many of the security capabilities that are built-in to Windows Server with a specific focus on what’s new to Windows Server 2019.

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Wells started off by explaining the SGX platform to further explain SGX Enclaves and its importance. SGX is a platform technology by Intel that provides a trusted execution environment on a machine that could be littered with malware and yet the trusted execution environment is able to defend itself from inspection, rights modifications, etc.

Microsoft has attempted to build a similar technology to SGX, but not as strong as SGX Enclave, called as the VBS (virtualization-based security) Enclave.

Wells says security threats is one of the key IT stress points. These threats further bifurcate into three areas:

  • Managing privileged identities
  • Securing the OS
  • Securing fabric virtualization (VMs) and virtualization-based security

Wells presented an 18-month-old data that highlighted that over three trillion dollars are impacted annually by cyber attacks; and it’s growing all the time.

Source: YouTube

He also presented an attack timeline to show how long it takes to find out to discover the attack. From the first entry point, it takes about an average of 24 to 48 hours to go from entry to the domain admin. These attackers dwell inside your network for around 146 days, which is alarming. The common factor in all the attacks is that attackers first seek out to exploit privileged accounts. However, one cannot actually deprecate these administrative power to avoid attacks.

Source: YouTube

How to secure privileged identities, OS, and fabric VMs in Windows Server 2019

Wells highlighted certain initiatives to address threats with Windows Server and/or Windows 10.

Managing privileged identities

Just-In-Time: Wells said that people should make sure they have privileged access workstations as this is another industry initiative that advice using workstations that are health attested and if they are not healthy, they will be unable to administer the workload assigned.

AAD banned password list: This is written by the Azure Active Directory Team. This takes AI and clever matching techniques the Azure AD uses in the cloud and brings them to Windows Server AD.

There are many identities on the platform but not everything is for everyone. One has to take proactive efforts to turn these features on.

Securing the OS

This is the area where one invests the most. In the past kernel was used to infuse code integrity; however, with Hypervisor the OS cannot directly communicate with the hardware. This is where one can lay new policies such as a code integrity policy. The Hypervisor can block things that a malicious kernel is trying to insert within the hardware. One can also secure the OS using a Control Flow Guard, the Defender ATP, and the System Guard runtime monitor.

Securing fabric virtualization (VMs) and virtualization-based security

These include Shielded VMs that are resistant to malware and host admin attacks on the very Hyper-V host where they are running. Users can also secure virtualization using Hyper-V containers, micro-segmentation, 802.1x support switches, etc.

To know more about each section in detail, head over to the video ‘Elevating your security posture with Windows Server 2019’.

What’s new in Windows Server 2019

Microsoft has made extensive use of Virtualization-Based Security (VBS) in the Window Server 2019 as this lays the foundation for protecting OS/workload secrets. The other features include:

  • Shielded VM improvements that include branch office support, simple cloud-friendly attestations, Linux OSes, and advanced troubleshooting.
  • Device Guard policy updates can now be applied without a reboot as there are new default policies shipped in-box and also that two or more policies can be stacked to create a combined effective policy.
  • Kernel Control Flow Guard (CFG) ensures that user and kernel-mode binaries run as expected.
  • System Guard Runtime Monitor runs inside the VBS Enclave keeps an eye on everything else and emits health assertions.
  • Virtual Network Encryption through SDN, which is a transparent encryption for the VMs.
  • Windows Defender ATP is now in-box hence no additional download is required.

Trusted Private Cloud for Windows

Mike Bartok from the NIST (National Institute of Standards and Technology) talked about trusted cloud and how NIST is trying to build on the capabilities mentioned by Dean. Bartok presented a NIST special publication 1800 series document that consists of three volumes:

Volume A: Includes high-level executive summary that can be taken to the C-suite to tell them about cloud adoption and how you will do it in a trusted manner. It also includes a high-level overview of the project, the challenges, solutions, benefits, etc.

Volume B: Takes a deeper dive into challenges and solutions. It also includes a reference architecture of various solutions to the problems, a mapping to the security controls in the NIST cybersecurity framework and 853 family.

Volume C is a technical How-to-Guide that shows every step implemented to reach the solution via screenshots, or will include pointers back to Microsoft’s installation guide. One can pick up the guide and replicate the project.

Security Objectives in Trusted Cloud

The Security outcomes of Trusted Cloud are categorized into foundational and those in progress. Foundational security outcomes include hardware root-of-Trust based and geolocation-based asset tagging; deploying and migrating workloads to trusted platforms with specific tags. However, the others that are in progress include:

  • Ensure workloads are decrypted on a server that meets the trust and boundary policies.
  • Ensure workloads meet the least privilege principle for network flow.
  • Ensure industry sector specific compliance.
  • Deploy and migrate workloads to trusted platforms across hybrid environments.

Each of these outcomes is supported by different partners including Intel, Dell-EMC, Microsoft, Docker, and Twistlock.

Virtualization Infrastructure Security

Multiple users have their hosts in the VM. They can say that the host is healthy because it is running fine. In a similar manner, there is no way a host could run without being provided with a key. That is how it is programmed to be.

Dean explains, a solution to the security concern is a Guarded fabric running Shielded VMs. A few security assurance goals for these Shielded VMs include:

Encryption of data both at rest and in-flight

Here, the virtual TPM enables the use of disk encryption within a VM (for eg. BitLocker). Also, both the live migration and the VM-state are encrypted.

Fabric admins locked out

Here, the host administrators cannot access guest VM secrets(e.g: can’t see disks, videos, etc.). Also, they cannot run arbitrary kernel-mode code.

Malware blocked: Attestation of host required

Here, VM-workloads can only run on healthy hosts designated by the VM owner.

However, Shielding is not intended as a defense against DoS attacks.

Shielded VMs in Windows Server 2019

Shielded VM is a unique security feature introduced by Microsoft in Windows Server 2016. In the latest Windows Server 2019 edition, it has undergone a lot of enhancements.

Includes Linux Guest OS support

The Linux Guest OS support in Windows Server 2019 supports Ubuntu, Red Hat (RHEL), and SUSE Linux Enterprise Server inside shielded VMs. Here the host should run on Windows Server 2019. Also, these shielded VMs will fully support secure provisioning to ensure the template disk is safe and trusted.

Host Key Attestation

In this Shielded VM enhancement, the VMs use asymmetric key pairs to authorize a host to run shielded VMs. This will be similar to how SSH works; no more AD trusts and no certification will be required. This will allow easier onboarding process with fewer  requirements and less fragility. This will further help to get a guarded fabric up and running quickly.

The Host Key Attestation has similar assurances to Active Directory attestation i.e, it checks only the host identity and not its length. Also, its best practises recommend the use of TPM attestation for most of the secure workloads.

Branch Office support

Here, the Hyper-V hosts can be configured with both primary and fallback HGS. This would be useful in cases where there is a local HGS for daily use and a remote HGS if the local HGS is down or unavailable. This support also enables the deployment of HGS in a shielded VM.

For completely offline applications, you can now authorize hosts to cache VM keys and start up VMs even when HGS cannot be reached. This is because Cache is bound to the last successful security/health attestation event, so a change in the host’s configuration that affects its security posture invalidates the cache.

Improved troubleshooting

Shielded VMs include enhanced VMConnect, which permits “fully shielded” VMs. This will assist troubleshooting and also can be disabled within the shielded VM.

PowerShell Direct is also permitted to shielded VMs. Here, one can combine with JEA to let the host admin fix only specific problems on the VMs without giving them full admin privileges. This can also be disabled within the Shielded VMs.

Windows Server 2019 Hyper-V vswitch and EAPOL

Dean also highlighted that Windows Server 2019 will have a full support for IEEE 802.1x port-based Network Access Control in Hyper-V switches. This support would be for VMs whose virtual NICs are attached to vSwitches.

Wells explained a bunch of reasons to try out and use Windows Server 2019 with new capabilities. If you need a few practical examples to effectively administer Windows server 2019 and want to harden your Windows Servers to keep away the bad guys, you can explore Mastering Windows Server 2019 – Second Edition written by Jordan Krause.

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