Welcome to AD Security 101. This blog series covers essential aspects of Active Directory (AD) security, offering basic concepts, best practices, and expert advice. I’ll start with a short discussion of why AD security is so important. Then I’ll dive into the series with one of the first steps you should take to protect AD: monitoring.
What is Active Directory?
Active Directory (AD) is a crucial component of your organization’s identity management system. This directory service is the central repository for all information about the organization’s users, computers, and other resources. As a centralized platform for managing user authentication and authorization, AD is critical to the security of your organization’s data and systems.
Through AD, administrators can assign permissions and access rights to users, control what resources users can access, monitor user activities, and much more. AD also integrates with other systems—such as Microsoft Exchange, SharePoint, and Skype for Business—to provide a single sign-on (SSO) experience for users, simplifying access to those resources.
Finally, AD is important for cloud-based applications and services in hybrid environments. On-premises AD provides a centralized and unified identity management system, synchronizing many security-critical objects and attributes to the cloud-based Azure AD.
Why do hackers attack Active Directory?
AD’s critical role makes it a primary target for cyberattackers. In recent years, almost every security breach has involved AD in some way. Cyber criminals understand the value of gaining control over AD.
By targeting AD, attackers can gain valuable information about an organization’s assets. They can then more effectively plan their attack to maximize their chances of success.
A successful AD attack can enable threat actors to move laterally across your organization—often undetected—and access sensitive information, applications, services, and resources.
As attackers gain increasingly elevated privileges, they can encrypt data and steal critical and sensitive information.
Attackers can also plant ransomware, disrupting operations and potentially causing financial loss, reputational damage, legal liabilities, and loss of intellectual property.
AD is a valuable service. But its age and the complexity inherent in large enterprise AD environments often makes it vulnerable to attack. To make matters worse, ransomware-as-a-service (RaaS) tools and scripts are now available for anyone to use, making the attack process easier than ever. Many experts have also cautioned that the introduction of AI tools like ChatGPT will make malware and ransomware creation even faster.
In response, Gartner has named identity threat detection and response (ITDR) as a top security and risk management trend and noted that AD security is a primary part of a strong ITDR strategy. (You can learn more about ITDR and ITDR solutions here.)
Why monitor Active Directory?
Cyber threat detection is a crucial aspect of any cybersecurity plan. The ability to identify unauthorized access, movements, or changes made to your network can help you respond quickly to—or even prevent—a security breach. A clear understanding of what changes are being made to AD and who is making them increases the likelihood that you’ll be able to identify and respond to potential threats before they can cause significant harm or disruption.
Monitoring changes in Active Directory is therefore an important component of ITDR and helps to ensure the security of your network. AD monitoring looks for indicators of exposure (IOEs): clues that a vulnerability exists and could be exploited by cyberattackers. It also looks for indicators of compromise (IOCs): signs that a breach has already occurred or is in progress.
Effective AD monitoring goes beyond implementing Security Information and Event Management (SIEM) systems. Although a useful network and system monitoring tool, SIEM solutions can leave gaps in your ability to determine who really did what and where. That’s because SIEM systems rely in large on system event logs, which don’t always provide a complete picture of what is happening in AD, as attackers develop ways to circumvent logging and hide the traces of their actions.
What to monitor in Active Directory?
So what does effective Active Directory monitoring look like? An AD monitoring solution should be able to detect changes made by any person, from any domain controller, using any tool—even those that hackers use from controlled computers. The solution should monitor specific, sensitive objects in AD, such as changes to membership of privileged groups. To achieve this, the solution must be able to monitor replication traffic between domain controllers and not rely solely on Windows event logs.
Tracking changes to the Domain Name System (DNS) is also important. DNS resolves computer names to IP addresses and locates servers that provide specific services, such as domain controllers. By monitoring changes to the DNS database (which is stored in AD), administrators can detect rogue devices and unauthorized modifications or additions to existing records that might indicate an attack in progress.
AD monitoring should also identify changes made to Group Policy Objects (GPOs), which are sets of rules for managing resources on a network. Unfortunately, by default, Windows event logs do not include details on changes within Group Policy. Therefore, a robust AD monitoring solution should detect any changes made to GPOs and trigger alerts.
What’s next in AD Security 101?
In the upcoming weeks, this AD Security 101 series will discuss items that you should closely monitor and regularly check and verify within your AD environment. This list will provide you with a solid foundation for enhancing AD monitoring, providing tips and guidelines that you can use to improve your AD security posture and gain easy wins against potential attackers. Don’t miss it!
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