Why Active Directory is your security perimeter

Active Directory (AD), a Microsoft Windows directory service, helps maintain a robust security perimeter within enterprise environments. It helps your business enforce security policies, assign permissions and mitigate security risks within the network. 

Let’s say your business’s IT infrastructure is a fortress, wherein AD acts as the gatekeeper controlling who enters and what they have access to. Just like a fortress, your IT kingdom needs strong overall security to safeguard your valuable digital assets like data, applications and IT systems. 

But what if your gatekeeper (AD) is compromised? An attacker might bribe the gatekeeper to gain illicit entry or sneak in while the gatekeeper is dozing off. It is up to you to ensure that only authorized people gain entry and control their movement in the castle. In the same way, if a disgruntled ex-employee or a skilled cybercriminal manages to obtain unauthorized access within your AD environment, it could lead to data breaches, business disruptions and reputational damage. 

With 90% of Global Fortune 1000 businesses running AD, they are one of the favorite targets of cyberattacks. To put it in perspective, cybercriminals attack 95M AD accounts daily and breach 1.2M Entra ID accounts every month. 

Since AD holds all the keys to your kingdom, it is imperative for businesses to maintain AD security to protect the organization’s credentials, applications and data from unauthorized access. 

Here are some strategies and best practices you can implement to protect your AD environment from malicious actors. 

The least privilege principle and AD security 

In the cybersecurity sphere, the principle of least privilege (POLP) entails granting users access to only the data and resources they need to perform their tasks. This principle, a fundamental component of a Zero Trust security approach, is also known as the principle of minimal privilege or least authority since it allows users access to the bare minimum of resources they require to function optimally. 

Why least privilege is essential 

Imagine a scenario where users are granted permission to several resources, even those they don’t need. It could give them access to data they shouldn’t be seeing and resources they shouldn’t be using, potentially leading to confidential data access and unauthorized modifications. The over-granting of permissions also widens the attack surface that could be used by attackers to exploit vulnerabilities or install malware and execute successful data breaches. 

Another adverse effect of granting excessive permissions is the privilege creep. It happens when users get unlimited rights due to a lack of oversight. They might also be granted the right to grant permissions, resulting in a complex web of unwarranted permissions. 

Conversely, a strong least-privilege (Zero Trust) policy can help CISOs prevent cyberattacks from happening in the first place, minimizing the need for auditing and recovery. This strategy focuses on a conscious management of user permissions. It allows securing your Active Directory by controlling access to privileged user data and critical digital resources while reducing the attack surface and the possibility of privilege creep. 

Here are a few key strategies you can use to implement least privilege in AD:  

  • Organize users in different departments into a separate AD security group and use role-based access control (RBAC) to grant permissions. 
  • Manage AD security groups carefully, avoiding exceedingly complex structures. 
  • Ensure service accounts have only the bare minimum permissions required to perform their tasks. 
  • Use separate administrative accounts and privileged access features of AD for sensitive tasks. 
  • Deny all access permissions by default and explicitly grant required permissions. 

Using tiered administration to Safeguard your AD 

Tiered administration includes organizing users and systems into multiple tiers (or levels). Each level represents a definite set of roles and abilities and is highly isolated from the other. This approach safeguards against privilege elevation by separating high-privilege roles from high-risk areas, providing a smooth user experience while also following best practices. 

In the case of an Active Directory environment, you can use separate accounts to implement the tiered management of systems. For it to work, you must ensure that privileged accounts in one tier cannot access systems in another. 

As an example, you may consider using the following tiers for your Active Directory administration:  

  • Tier 0: This tier holds the organization’s most critical digital assets like domain controllers. Since these assets are the most privileged, they are in the crosshairs of cybercriminals. A Tier 0 compromise often results in a complete IT infrastructure breach, potentially causing severe operational, reputational and financial damage to the business. Tightly managing this tier’s accounts and resources by limiting access to only trusted personnel can help mitigate any serious threat. You can secure your Active Directory by segregating Tier 0 accounts from other systems or even creating a new Active Directory forest to manage its accounts. Also, consider using Privileged Access Management (PAM) solutions to double its protection from internal or external threats. 
  • Tier 1: The systems in this tier are less critical than those of Tier 0 and represent enterprise servers, applications and services crucial to business operations. Even if Tier 1 is breached, the ripple effects won’t reach Tier 0 or other systems provided they are completely isolated. 
  • Tier 2: All systems not present at Tier 0 and Tier 1 levels constitute Tier 2. It mostly contains end-user devices like laptops, desktops, printers, hand-held devices and other user-level devices. These devices are isolated from Tiers 0 and 1 and can only manage and access resources in the Tier 2 level. 

While an administrator can create any number of tiers, it is advisable to keep it simple lest it becomes a management disaster. 

Be proactive with regular auditing 

Auditing AD entails regularly tracking and logging events when Microsoft’s AD is in use. It is a process of recording and reviewing actions like logins, resource access, account changes, group policy modifications and other related actions occurring within the AD environment. The resulting information is further used to identify potential security risks and ensure security protocol compliance. 

Continual auditing of privileged accounts is crucial to prevent data compromise or cybersecurity incidents. It maintains Active Directory integrity by spotting unauthorized access and any changes to privileged account settings. In addition, regular audits offer valuable investigative data in case of a breach, facilitating rapid detection and response to security incidents. 

Different organizations implement AD with different strategies so there is no one way to audit it. However, since AD contains the key to your organization’s digital fortress, identifying any activity that violates your standard protocol and might lead to serious consequences is paramount. Also, since alert fatigue is real, you must monitor only a few significant events that demand prompt response amidst an overwhelming amount of activities. 

Here is a sample list of key events you can audit to prevent AD security incidents:  

  1. New account creation: Creating new Active Directory user accounts increases your AD surface area and exposes your data to a larger user base. 
  2. Privileged group activities and modifications: Carefully monitor and trace the activities of privileged groups like Domain or Enterprise Admins as they hold enormous power over enterprise data and can be misused by their owners or external entities. 
  3. Group policy modifications: Changing only a single configuration like allowing unlimited password attempts or access to unidentified devices in your Group Policy object could significantly expose your digital kingdom. 
  4. A spike in user account lockouts: A sudden rise in account lockouts implies a brute-force attack and can interrupt critical operations. 
  5. AD logons: Keep an eye on unusual logon/logoff activities to identify security vulnerabilities and non-compliance. 
  6. Password modifications: Often cybercriminals successfully penetrate AD systems with just a correct password guess. Implement stringent password policies and closely monitor password resets and changes. 

User education is your first line of defense 

Another crucial practice to secure your AD environment is educating users accessing AD at all levels regarding security threats and appropriate behavior. 

There are several improper user behaviors you must monitor to secure your AD environment. Some common examples include:  

  • Nonstandard permission modifications 
  • Logon from unfamiliar locations or at unusual times 
  • Multiple failed logon attempts 
  • Suspicious resource access, data transfers or file downloads 
  • Sudden traffic spikes 
  • Succumbing to phishing attacks 
  • Unauthorized AD or Azure cloud access 

Training users to properly use AD is your first line of defense and can help raise understanding of security vulnerabilities and awareness about standard security protocols, plus the repercussions of violating them. Training and education can also bolster positive security behavior among AD users, such as using multifactor authentication, preventing phishing and being vigilant of security incidents. 

To ensure proper user behavior and secure your AD kingdom:  

  • Establish strong access policies and educate users on the dire consequences of violating them. 
  • Make users create strong passwords and change them at regular intervals to enhance your data security posture. 
  • Ensure daily backups for effective disaster recovery in case of a compromised system. 
  • Train your employees to identify suspicious emails and not to click on doubtful links to prevent phishing and social engineering attacks. 

Bolster your AD security now 

AD holds all the keys to your kingdom, making its security an utmost priority. In the face of ever-evolving cyber threats, you must ensure using various strategies, such as the least-privilege principle, tiered AD management, regular auditing, and user training and education to bolster your AD security. 

Over-granting permissions may seem like an easy fix, but in the long run, it brings about a host of vulnerabilities like privilege creep, widened attack surface and unauthorized access. A single point of entry is enough for attackers to wreak havoc in your digital fortress and cause significant damage to your business repute and financial assets. Therefore, it is essential to strike the right balance between ease of accessibility and security for protecting your business’s valuable IT assets. Fortify your active directory and overall security posture by implementing effective strategies against the ever-increasing cyberattacks. 

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