The Microsoft Active Directory (AD) infrastructure represents the cornerstone of identity and access management for a vast majority of organizations globally. Its centrality in controlling authentication, authorization, and security policies makes it a primary target for cyberattacks. A compromised AD environment can lead to devastating consequences, including the loss of sensitive data, service disruption, and significant reputational damage.

To effectively counter these threats, organizations are increasingly relying on ethical hacking. This article serves as a practical and in-depth guide on the most common attack techniques targeting Active Directory, illustrating how ethical hackers replicate them to uncover weaknesses, and providing guidance on detection methods and mitigation strategies.

Why is Microsoft Active Directory a critical target?

Active Directory is a complex system that manages thousands of objects, interacting with each other through intricate configurations, permissions, and relationships. This complexity, while necessary for managing large IT environments, can also hide misconfigurations and exploitable vulnerabilities.

After gaining initial access to an environment with Active Directory, malicious attackers frequently conduct an enumeration phase to gather detailed information about the structure, objects, configurations, and relationships specific to each organization. By acquiring a deep understanding of the AD environment, often superior to that of the organization itself, cybercriminals can target systems with a higher probability of success, leveraging weaknesses and misconfigurations to escalate privileges, move laterally within the network, and, ultimately, gain complete control of the Active Directory domain.

Although significant access can also be obtained by compromising other user accounts, such as service accounts, preventing attackers from acquiring maximum privileges is fundamental to limiting their overall reach. Therefore, securing Active Directory should be an absolute priority for all organizations.

Common attack techniques on Microsoft Active Directory

Ethical hackers, armed with knowledge of real-world adversary tactics, techniques, and procedures (TTPs), simulate a series of common attacks to assess the security of Active Directory. Some of the most widespread techniques are illustrated below:

Kerberoasting

Kerberoasting is an attack technique that exploits the Kerberos authentication system to obtain credentials. Attackers look for user accounts (often service accounts) that have a Service Principal Name (SPN) registered. An SPN identifies an instance of a service to which an account is associated. When a user requests a Kerberos service ticket (TGS) for a service with an SPN, the Key Distribution Center (KDC) issues a ticket encrypted with the service account’s password.

Attackers can request these TGSs and, because they are encrypted, they can be downloaded and attempted to be cracked offline via brute-force attacks to reveal the service account’s plaintext password. Once a service account is compromised, attackers can leverage the permissions associated with that account, which in some cases can be elevated.

Kerberoasting can be detected by analyzing events on Domain Controllers. Events with ID 4769 are generated when a TGS ticket is requested. A high number of TGS requests for the same service account in a short period or requests with RC4 encryption type (value ‘0x17’ in the “Ticket Encryption Type” field), which is less frequently used, can indicate Kerberoasting activity.
Additionally, specific values in the “Ticket Options” field (‘0x40800000’ or ‘0x40810000’), often used by attack tools, can be indicators. Rapid changes to user accounts that add and remove SPNs (events 4738 and 5136) may also suggest attempts to prepare for a Kerberoasting attack.

Mitigation:

• Use strong and unique passwords for all accounts, including service accounts.
• Monitor security events on Domain Controllers for suspicious activity related to Kerberos ticket requests.
• Apply the principle of least privilege, ensuring that service accounts have only the permissions necessary to perform their functions.
• Limit the use of RC4 encryption for Kerberos tickets, where possible, as it is more susceptible to brute-force attacks.

AS-REP Roasting

The AS-REP Roasting technique targets users who have the “Do not require Kerberos preauthentication” option enabled on their accounts. In this configuration, when a user requests a ticket-granting ticket (TGT) from the KDC (Authentication Server – AS), the KDC responds with a TGT partially encrypted using the user’s password as a key, without requiring pre-authentication.

An attacker can exploit this setting to request TGTs for target accounts. The received TGT, although not fully usable without the password, contains information that can be extracted and subjected to offline cracking attempts to recover the user’s password.

Detecting AS-REP Roasting can be complex because the activity itself is a valid Kerberos authentication request. However, a high number of AS requests for specific accounts with the “Do not require Kerberos preauthentication” option enabled, especially if originating from a single suspicious source, could be a clue. The use of Active Directory canaries, dummy accounts created specifically to be read by attackers during reconnaissance, can help detect enumeration activity associated with this technique.

Mitigation:

• Disable the “Do not require Kerberos preauthentication” option for all user accounts, unless strictly necessary and justified by specific application requirements.
• Monitor changes to user accounts that might enable this option.
• Implement Active Directory canaries to detect suspicious reconnaissance activity.

Password spraying

Password Spraying is a “low and slow” brute-force attack that attempts to authenticate to multiple user accounts using a limited number of common passwords. The goal is to exploit weak or reused passwords across multiple accounts while minimizing the risk of account lockout due to too many failed login attempts on a single account. The passwords used can come from public lists of common passwords or be derived from specific information about the target organization to increase the probability of success.

If an attacker manages to compromise an account via password spraying, they gain control of that account and inherit its access and privileges. This technique is particularly effective against organizations where password reuse is widespread.

Password Spraying can be detected by monitoring authentication logs on Domain Controllers for a large number of failed login attempts originating from a single IP source or a limited number of IP sources, directed at a high number of different user accounts. Security Information and Event Management (SIEM) systems are valuable tools for correlating these events and identifying suspicious patterns.

Mitigation:

• Enforce strong and complex password policies and mandate their periodic rotation.
• Implement account lockout after a limited number of failed login attempts.
• Enable multi-factor authentication (MFA) to add an extra layer of security.
• Monitor authentication logs for suspicious activity.
• Educate users on the importance of unique and complex passwords and the risks of password reuse.

DCSync

DCSync is a post-compromise attack technique that allows an attacker with compromised credentials (often by obtaining Domain Admin privileges) to replicate Active Directory data from a Domain Controller, including user password hashes and other sensitive attributes. This technique exploits the replication protocol used by Domain Controllers to synchronize information between them.

An attacker executing a DCSync attack can obtain the password hashes of all users in the domain, including accounts with the highest privileges, without actually having to physically or locally access a Domain Controller. These hashes can then be used for offline password cracking attacks or for “pass-the-hash” attacks to authenticate to other systems.

Detecting DCSync can be challenging because it exploits a legitimate communication protocol. However, it is possible to monitor events on Domain Controllers related to replication requests. Events with ID 4662 showing access to Active Directory objects, particularly the Directory Service object, by accounts not authorized for such replication operations, or an unusually high volume of replication traffic originating from a compromised host, can be indicators of DCSync. The use of Active Directory canaries can also help detect attempts to access canary objects associated with this technique.

Mitigation:

• Strictly protect accounts with elevated privileges, limiting the number of accounts that are members of the Domain Admins and Enterprise Admins groups.
• Carefully monitor security logs on Domain Controllers for anomalous replication activity.
• Implement the principle of least privilege for all accounts.
• Strengthen endpoint security to prevent the compromise of privileged accounts.

Golden Ticket

A Golden Ticket is a forged Kerberos ticket-granting ticket (TGT) that allows an attacker to authenticate to any service within the Active Directory domain. This technique can be performed if an attacker has compromised the krbtgt account, the service account used by the KDC to sign all Kerberos tickets. Obtaining the password hash of the krbtgt account (often via DCSync) allows the attacker to create forged TGTs that are considered valid by all members of the domain.

Golden Tickets grant persistent and unlimited access to the AD environment, allowing attackers to perform any action as if they were a domain administrator, without leaving significant authentication traces after the ticket is created.

Detecting Golden Tickets is difficult because forged tickets appear legitimate. However, some anomalies can be detected:

• Ticket requests with an unusually long validity period.
• Ticket requests originating from non-Domain Controller hosts for sensitive services that would normally require interaction with a DC.
• Use of inconsistent PAC (Privilege Attribute Certificate) values.
• Monitoring unauthorized changes to the krbtgt account (events 4765 and 4766).

Mitigation:

• Protect the krbtgt account extremely rigorously. The password should be long, complex, and rotated regularly (ideally following best practices for encryption key management).
• Carefully monitor security logs on Domain Controllers for anomalies in Kerberos ticket requests.
• Implement advanced detection solutions capable of analyzing Kerberos traffic for indicators of Golden Tickets.
• Follow best practices for securing privileged accounts, including minimizing their use and implementing jump servers (bastion hosts).

Silver Ticket

A Silver Ticket is a forged Kerberos service ticket (TGS) that allows an attacker to gain access to a specific service on a specific machine within the Active Directory domain. Unlike the Golden Ticket, which requires the compromise of the krbtgt account, a Silver Ticket can be created if an attacker has compromised a user or computer account with sufficient privileges to extract the password hash of a specific service account on the target machine.

With a forged TGS, the attacker can authenticate directly to the target service (e.g., the file server service via CIFS/SMB, LDAP, SQL Server, or the HOST service for access via PowerShell Remoting) without having to interact with a Domain Controller for service authentication.

Detecting Silver Tickets is particularly complex because authentication is isolated between the attacker and the target machine, avoiding logs on Domain Controllers. To detect a Silver Ticket, it is necessary to analyze events on the target machine. It is less common for organizations to log authentication events on all workstations and servers, making detection more difficult. Monitoring security events on the target machine related to the use of targeted services, particularly anomalous or unexpected access requests, can provide clues.

Mitigation:

• Strictly protect service account passwords on every machine.
• Implement the principle of least privilege for all user and service accounts.
• Monitor security logs not only on Domain Controllers but also on critical servers and workstations for anomalous service authentication activity.
• Ensure the “Domain Computers” security group does not have write or modify permissions on any object in Microsoft Active Directory. All computer objects are members of this group, and if it has rights on other objects, attackers could exploit them to compromise other systems and escalate privileges.

Active Directory Certificate Services (AD CS) Compromise and Golden Certificate

The compromise of Active Directory Certificate Services (AD CS) can lead to advanced attack scenarios, including the issuance of fraudulent certificates to impersonate any user or service in the domain. If an attacker gains administrative access to a Certification Authority (CA), they can extract the CA certificate and the private key.

Once obtained, these elements can be used to forge Golden Certificates, which are valid client authentication certificates that allow the impersonation of any other user object in the domain. Certificates created with the extracted CA private key are considered valid within the domain until they are revoked. If revocation is not managed periodically, the certificates could remain valid indefinitely, granting the attacker long-term persistence on the network.

Detecting AD CS compromises requires monitoring events related to certificate management and changes to CA configurations. Events with ID 4900 on CA servers indicate changes to certificate template security settings, which could introduce vulnerable conditions such as modifying enrollment rights.

Mitigation:

• Strictly protect AD CS servers, limiting administrative access.
• Monitor changes to certificate templates and enrollment permissions.
• Implement strict controls on the certificate issuance and revocation process.
• Use tools to identify AD CS vulnerabilities such as Certificate Manager (certmgr.msc), Certutil, PSPKIAudit, and Certify.
• Follow specific hardening guidelines for AD CS.

How attack simulation is performed

Ethical hackers conduct their simulations following a structured methodology that includes planning and reconnaissance, scanning, exploitation, and analysis and reporting phases. However, unlike a penetration test, ethical hacking on complex infrastructures like Active Directory involves more advanced techniques, the development of custom tools to uncover hidden vulnerabilities, and attacks on the human factor (Social Engineering). To learn more about the role of the human component in these scenarios, it is useful to read how social engineering integrates into ethical hacking.

Ethical hackers use a wide range of tools to simulate attacks against Microsoft Active Directory. Some examples include:

• Mimikatz: a powerful tool for extracting credentials from memory, including password hashes, Kerberos tickets, and CA keys.
• Metasploit Framework: an open-source framework used to develop and execute exploits, conduct reconnaissance, and post-exploitation activities.
• Acunetix and Nikto: web vulnerability scanners that can identify weaknesses in web applications that interact with Microsoft Active Directory.
• Custom tools and scripts developed to simulate specific TTPs.

A crucial phase in the ethical hacking process is analysis of results, which relies heavily on logging and auditing. Logs provide a detailed record of the actions taken by ethical hackers during the simulation, allowing for the reconstruction of attack paths, identification of exploited vulnerabilities, and assessment of the effectiveness of defense mechanisms. Protecting the integrity of logs and analyzing data in a timely manner is fundamental to transforming the results of ethical hacking into concrete actions to improve cybersecurity.

If the security of your Microsoft Active Directory environment is a priority, consider adopting a proactive approach through regular ethical hacking assessments to stay one step ahead of ever-evolving threats.

What requirements must an ethical hacker have to work on Microsoft Active Directory?

An ethical hacker specializing in Active Directory (AD) must possess a broad spectrum of technical and methodological skills, given the complexity and criticality of this directory service, which is often a primary target for attackers due to its central role in authentication and authorization within organizations.

First and foremost, a deep knowledge of AD architecture is fundamental, including its main components such as domains, forests, trust relationships, Group Policy Objects (GPOs), and the structure of objects (users, groups, computers). They must understand authentication mechanisms (Kerberos, NTLM, LDAP) and their related vulnerabilities, as well as the frequently incorrect configurations that can expose the environment to significant risks.

On a technical level, the ethical hacker must master advanced attack techniques specific to AD, including:

• Kerberoasting and AS-REP Roasting
• Pass-the-Hash and Pass-the-Ticket
• DCSync
• Golden Ticket and Silver Ticket
• Password Spraying and Brute Force

They must also be expert in the use of specialized tools such as:

• BloodHound
• Mimikatz
• Impacket
• ADExplorer and PingCastle

Beyond technical skills, knowledge of structured frameworks and methodologies is essential, such as:

• MITRE ATT&CK, to simulate real techniques used by adversaries
• Threat-Led Penetration Testing (TLPT), especially in regulated contexts like the financial sector (DORA, TIBER-EU)
• OSCP/OSEP for practical approaches to exploitation

A crucial aspect is the use of threat intelligence to contextualize simulated attacks, based on real and current threats. The ethical hacker must also strictly adhere to defined scopes and authorizations, ensuring that activities are conducted ethically and in compliance with regulations.

Finally, they must be able to clearly and detailedly document the identified vulnerabilities, the exploited attack paths, and recommendations for remediation, producing reports that support the organization in strengthening its security. To get a complete picture of ethical hacking terminology and fundamental concepts, a reference glossary is available.

Training and experience:

In addition to technical skills, an ethical hacker operating on Microsoft Active Directory must possess solid training and consolidated practical experience. Given the complexity of AD environments and the continuous evolution of attack techniques, a structured learning path is essential, which includes:

• Recognized certifications in the field of cybersecurity
• Specialized courses on Microsoft Active Directory, covering both administration and hardening aspects as well as ethical hacking, such as Active Directory Security, Red Teaming, and AD Exploitation.
• Participation in practical labs, which allow testing skills in realistic scenarios, simulating advanced attacks and complex defenses.

Field experience is equally crucial. An effective ethical hacker must have gained years of practice in penetration testing, red teaming, and security assessments, facing AD environments in diverse organizational contexts. Only through continuous exposure to real-world scenarios is it possible to develop that tactical mindset necessary to:

• Identify undocumented vulnerabilities or misconfigurations that are not immediately evident.
• Understand adversary behavior and anticipate their moves.
• Adapt to regulated contexts (such as finance or healthcare), where assessments must comply with specific standards (e.g., DORA, NIS2).

Finally, an ethical hacker must maintain a continuous learning approach, constantly updating themselves on new threats and emerging tools. Specialized forums, conferences, and threat intelligence sharing are valuable resources for keeping up with an ever-evolving cyber landscape.

Working on Active Directory as an ethical hacker requires a combination of advanced technical skills, deep knowledge of AD, familiarity with attack/defense tools and methodologies, and analytical and reporting capabilities, in addition to strict adherence to ethical and regulatory principles. Only with this holistic approach is it possible to effectively identify and mitigate risks in AD environments, contributing to building more resilient infrastructures.

Frequently asked questions about ethical hacking on Active Directory

Some questions that often arise when evaluating ethical hacking activity on Active Directory environments.

• What is the difference between a penetration test and an ethical hacking activity on Active Directory?
• A penetration test on AD follows a defined scope and tests known vulnerabilities within a limited time. Ethical hacking is a broader approach: it includes advanced techniques, development of custom tools, attacks on the human factor, and simulation of realistic scenarios that replicate the behavior of a real adversary. The goal is not just to find flaws, but to understand how far an attacker could go.
• How often is it advisable to perform an ethical hacking assessment on the AD environment?
• There is no universal answer, but in general, it is appropriate to plan at least an annual assessment, supplemented by targeted checks after significant infrastructure changes (migrations, mergers, new cloud integrations, GPO changes). In regulated sectors like finance or healthcare, the frequency may be mandated by specific regulations such as DORA or NIS2.
• What does the final report of an ethical hacking activity on Active Directory typically include?
• The report documents the identified vulnerabilities, the exploited attack paths, the techniques used with reference to the MITRE ATT&CK framework, a risk assessment for each criticality, and prioritized remediation recommendations. A good report always distinguishes between structural configuration issues and operational weaknesses, providing concrete guidance for both.