Preventing Insider Threats in Your Active Directory

Active Directory (AD) is a widely used authentication and directory service that empowers organizations worldwide. However, its broad reach and capabilities can be misused, especially by insiders. These insiders pose a considerable risk as many of them are granted excessive access and visibility into the internal network.

Due to their level of access and trust within the network, insiders present distinct vulnerabilities. Unfortunately, network security frequently concentrates on preventing threat actors from outside instead of safeguarding current users and potential weaknesses. Therefore, it is necessary to stay vigilant against both internal and external threats to ensure adequate protection.

Active Directory Vulnerabilities

While a properly configured AD domain offers secure authentication and authorization, it is not invulnerable. Complex social engineering and phishing email attacks can compromise existing AD users, giving attackers a foothold inside the network. Once inside, they have multiple options to attack Active Directory.

• Insecure Devices

As "Bring Your Own Device" (BYOD) increases, device support and security complexity grow. If users connect a compromised or inadequately secured device, attackers gain an easy path to access the internal network.

Previously, attackers had to sneak in to install malicious devices. Now, users with compromised devices unwittingly do the hard work for them. Furthermore, many workers may connect their smartphones or tablets to the network, meaning you may have multiple user devices that lack the same security measures as work-issued laptops.

• Over-Provisioned Access

Adding complexity to internal security, over-provisioned access is a common problem. Organizations tend to expand access instead of restricting it. One act of convenience can create a potential attack vector, which is often forgotten.

For users who are also administrators, there may not always be a highly secure "Administrative" account that separates different access levels. Allowing Administrative tasks through a standard user account opens the door to rampant abuse via a compromised, highly privileged account.

• Weak Password Policies

Larger organizations may have weaker password policies due to the various applications they support. Some applications do not support the latest security standards, such as LDAP signing or TLS over LDAP with LDAPS.

A weak password policy coupled with a lack of multi-factor authentication makes it easy to crack a retrieved hash through a technique like Keberoasting, using a privileged internal account.

Best Practices for Securing Active Directory

There are several best practices to follow when securing Active Directory. These include restricting access to systems and networks to those with a legitimate business need, ensuring that connected devices meet a minimum standard of security, and configuring Active Directory securely with LDAP signing and LDAPS requirements. Additionally, it is recommended to regularly rotate the KRBTGT password and use group-managed service accounts (gMSA) to rotate service account credentials.

Enabling multi-factor authentication and implementing a strong password policy, supplemented by solutions such as Specops Password Policy, is also crucial. Separating permissions from typical user accounts and assigning them to special administrative accounts can help enhance security. Moreover, it is essential to educate users about the dangers of phishing emails and social engineering attacks, such as clicking on attachments. Training users to identify potential phishing emails and social engineering attacks, and discouraging them from clicking on attachments, can help mitigate the risk of a successful attack.

In the event that Active Directory has already been compromised, an organization should conduct a thorough analysis of the permissions assigned to active and non-active or decommissioned users and systems. Separating permissions from typical user accounts and assigning them to special administrative accounts with a higher security level can help prevent similar breaches in the future. Enabling multi-factor authentication and enforcing a strong password policy can also provide robust protection against attacks, as social engineering attacks often rely on compromised user passwords.

Conclusion

While it may not be feasible to safeguard against every possible threat, conducting a comprehensive analysis of existing permission structures, active users, and the technical implementation of Active Directory can significantly enhance an organization's security posture. By doing so, an organization can take significant steps towards securing its environment.