Hardening Active Directory Security Gaps

Active Directory Federation Services (AD FS) (2)

Active Directory is an integral component of network security. If hackers gain entry, they could gain control over all services connected with it and potentially gain access to sensitive information stored therein.

Adopting best practices for Active Directory security is vitally important, including: implementing network security best practices, deploying IPSec for secure communication among AD components and monitoring privileged account changes using third-party solutions.

Identifying Vulnerabilities

As Active Directory environments mature, IT administrators often make errors that leave the door wide open for attackers. Misconfigurations may allow attackers to gain entry and compromise sensitive data – including credentials and identity data – that would otherwise remain protected from exposure. While some errors can be easily remedied, others require greater effort; it is crucial that AD administrators identify and understand where gaps in security exist to effectively harden it against threats.

Purple Knight can help your Active Directory environment identify vulnerabilities through periodic scans that monitor for them, increasing awareness of risky configurations and alerting to possible exploits.

Microsoft has undertaken to plug holes in their system, yet attackers continue to find multiple ways to exploit weaknesses within it. From system vulnerabilities to insider threats that seek privileged access and spread laterally across domains, attackers have found multiple means of taking advantage of weaknesses within.

Your Active Directory environment uses Kerberos authentication, which has multiple flaws which attackers continue to exploit. They use this vulnerability to break into networks and take over them en masse by exploiting man-in-the-middle attacks, authentication coercion and password cracking methods.

AD is fraught with vulnerabilities due to hidden permissions, nested group membership structures and inherent security flaws that allow an attacker to quickly take full control of your environment if an account in one of the Enterprise Admins, Domain Admins or Schema Admins groups can easily be added into another group with administrative privileges – potentially giving an attacker complete control.

Password Mismanagement Attackers can bypass authentication systems, pose as legitimate users and even install code to compromise your server, leading to serious security issues for your network. Therefore it’s essential that strong password policies be implemented with limited administrator access granted only to those requiring it for their job functions.

Attackers don’t typically search for needles in haystacks; rather they prefer prowling parking lots for quick routes to your organization’s data. Therefore, adopting simple security practices and monitoring for changes are so essential to protecting your organization’s information assets.

Patching Vulnerabilities

As a key part of Windows infrastructure, Active Directory is used by businesses, government agencies and other organizations worldwide to manage user accounts and access digital resources; it plays a pivotal role in protecting from data leaks, employee-data theft and ransomware attacks; however it can also become vulnerable due to misconfigurations which expose your organization to security vulnerabilities that leave it open to leaks, theft and ransomware attacks.

Your primary objective should be reducing your attack surface by employing best practices for securing AD. Some examples include removing default permissions from basic security groups like Account Operators; performing configuration audits on endpoints, servers and other systems in order to identify unintended drift or malicious changes; and keeping patch management up-to-date.

Active Directory’s most-susceptible vulnerability lies with privileged accounts. When an attacker gains access to one, they can then elevate their privileges and move laterally across the network, corrupting systems and stealing sensitive information. Therefore, it’s crucial to monitor privileged account activity, including logins from remote locations outside normal working hours, in order to detect signs that an attack might be underway.

Microsoft released several patches that address Active Directory vulnerabilities last November, with priority given to applying these updates on domain controllers, since these updates address privilege bypass and elevation of privilege vulnerabilities that attackers often exploit.

The first protection addresses a bug that allows an attacker to impersonate a domain controller with low-privileged credentials, using an exploit in how KDC (Key Distribution Center) searches machine accounts to obtain service tickets; if an account named user$ exists on a domain controller, an attacker could quickly gain access to one and take over its control.

Another patch addresses a vulnerability which allowed an attacker to bypass authentication controls and gain administrator rights on a domain controller by altering an LDAP attribute value using command line arguments. The patch closes a flaw in how domain controllers check whether an LDAP modify request matches up with user accounts with similar names.

Monitoring Vulnerabilities

Once an attacker gains access to your Active Directory, they have full control of its connected users, applications and databases – giving them access to everything from ransomware deployment and theft of data to taking over an entire network. While most attacks against AD do not start off with zero day vulnerabilities as their scope widens.

Active Directory security lies in creating an insurmountable barrier against attackers, by limiting their attack surface of your AD environment and implementing strong security practices to deter them from finding gaps and vulnerabilities that are easily exploitable.

AD environments often contain excessive domain administrator accounts or orphaned service account passwords that never change, making them an excellent target for kerberoasting attacks. Weak passwords or no passwords at all make these service accounts vulnerable to brute force attacks as well. Stale and outdated accounts also present vulnerabilities; administrators who fail to adjust staff or role changes often leave behind service accounts that remain within the system too long and become an easy target.

Mistakes and vulnerabilities caused by default security settings can often be corrected through the application of security patches to your AD servers and associated systems, along with encrypted communication channels between AD components to help avoid eavesdropping attacks, firewalls and network segmentation, as well as providing a barrier between your Active Directory environment and other IT components.

However, these steps alone may not provide your organization with enough protection from Active Directory-related attacks. One common path to data breach involves compromised accounts gaining entry to an AD environment through which attackers gain entry and use it to escalate privileges or move laterally through IT infrastructure. To best safeguard your company against Active Directory threats, monitor all changes made by any administrator as they occur compared with your environment’s known good state – this helps identify any unintended drift or malicious changes that might be exploited by an attacker.

Disaster Recovery

When Active Directory goes down due to cyberattack or natural disaster, all aspects of an organization come to a standstill until its back up and running again. That is why all businesses must create and test an emergency recovery plan for AD that includes testing backup copies as well as recovering to an earlier known secure state before any incident arises.

To prepare for Active Directory failures, it’s critical to regularly create backup copies and store them somewhere accessible in case of outages. Microsoft recommends following its 3-2-1 rule of storing three backups on two types of storage and at least one offsite location; additionally it is also important to choose an appropriate type of backup tool; in my experience BMR provides an ideal solution.

As soon as a backup has been restored, it’s crucial to conduct a comprehensive verification and identify any changes since the previous backup was taken. For example, if the last restored version of an AD forest contained numerous security patches that must match those found in its backup if restoration may result in corrupted or otherwise inoperable AD forests.

An effective communication plan for when AD is down is equally as essential to ensure IT team members can coordinate effectively when dealing with this situation. This is especially vital if your IT team relies on AD-authenticated services such as email or team collaboration tools such as Microsoft Teams for communications; should these go down simultaneously, working as one will likely prove more challenging.

An essential step in disaster recovery is eliminating legacy protocols from your network, such as TLS 1.0 and 1.1, Server Message Block v1 (SMBv1) and NTLMv1 and NTLMv2 authentication systems that are outdated against modern threats and should be phased out as quickly as possible.

An Active Directory security strategy that addresses malware as the number-one threat to operational resilience is of utmost importance. According to Mandiant researchers, identity systems are an attractive target for attackers, accounting for 9 out of every 10 cyberattacks on organizations. Prioritizing cyber-first disaster recovery for AD can reduce downtime while eliminating reinfection with malware reinfection while providing post-breach forensics.

Mark Funk
Mark Funk is an experienced information security specialist who works with enterprises to mature and improve their enterprise security programs. Previously, he worked as a security news reporter.