Industry data (like from Forrester Research) shows that most attacks involve using compromised credentials. And while all administrative accounts are a target for hackers, privileged Active Directory accounts are the golden goose because they can be used to get privileged access to any domain-joined system. Hackers use lateral movement to hop from end-user devices to sensitive systems. Or, from one end-user device to another until they find privileged credentials.
Users with local administrative privileges can easily infect their devices with malware that’s able to harvest cached credentials from memory. If a privileged AD user then logs in to an infected device, locally or remotely, the malware can harvest the credentials, allowing it to move from the user’s device to more sensitive systems.
This is just one example of how hackers use lateral movement to compromise sensitive systems. Other methods, like Pass-the-Hash (PtH), also rely on a privileged account logging in to a system that’s been infected by malware using local administrative privileges.
The best way to protect your systems is to ensure that privileged AD accounts are never used for administration of devices that don’t have the same level of trust as domain controllers.
Protecting end-user devices by restricting the use of local administrator privileges is a good idea. But domain controllers are ‘special’ and should be secured for a much higher level of trust. Unlike end-user devices, domain controllers are usually physically secured in datacenters, not used for Internet browsing, are subject to strict request for change procedures, and use delegation so that IT staff can administer AD without requiring privileged accounts. Following security best practices for domain controllers reduces the likelihood of malware infection.
Tiered administrative model can help
Microsoft recommends using a tiered administrative model in Active Directory to protect privileged AD credentials. This involves categorizing your IT assets into three tiers. Tier 0 is the highest level of trust and includes domain controllers, privileged AD accounts and groups, and devices and domains that can manage domain controllers. Tier 0 administrators are only allowed to log in interactively to Tier 0 devices but can manage assets in all tiers. Tier 1 consists of domain member servers and applications, and Tier 2 is for end-user devices.
The administrator accounts for each tier are restricted from logging in interactively to systems in the tiers above, helping to ensure that sensitive systems cannot be easily compromised by accounts used for managing systems with lower levels of trust. This model makes it harder for hackers to move from end-user devices to more sensitive systems but doesn’t make it impossible. However, in combination with other best practices, the tiered administrative model is an effective defense.
Join me in my webinar “Protect Privileged Active Directory Credentials Using a Tiered-Administrative Model” where I’ll explain more about the tiered administrative model and show you how it works in practice, including automating the creation of Microsoft’s recommended OU structure and groups, populating privileged AD groups using AD DS management accounts, and managing domain controllers using Privileged Access Workstations (PAWs). Then, BeyondTrust will present their capabilities to augment this functionality.
Russell Smith, IT Consultant & Security MVP
Russell Smith specializes in the management and security of Microsoft-based IT systems. In addition to blogging about Windows and Active Directory for the Petri IT Knowledgebase, Russell is a Contributing Editor at CDW’s Biztech Magazine.
Russell has more than 15 years of experience in IT, has written a book on Windows security, co-authored one for Microsoft’s Official Academic Course (MOAC) series and has delivered several courses for Pluralsight.