Group Membership

Windows Group Memberships play a critical role in the security and management of Windows environments, acting as a cornerstone for defining access controls and privileges across networked systems and resources. With the introduction of new auditing capabilities in Windows 10 and Server 2016, Microsoft has significantly enhanced the ability of administrators and security professionals to detect and respond to enumeration activities targeting these sensitive groups and accounts. Enumeration of accounts and groups is a common tactic in the reconnaissance phase of an attack, allowing attackers to identify valuable targets for escalation of privileges or lateral movement within a network.

The Role of Group Memberships in Security

Group memberships define the access level and permissions that user accounts have within a Windows environment. Sensitive groups, such as Domain Admins, Enterprise Admins, and local Administrators, provide elevated privileges that are often targeted by attackers to gain control over systems and data.

Enumeration Tools and Techniques

Tools like PowerView and frameworks such as Empire and PowerSploit have made it easier for attackers to automate the discovery of valuable accounts and group memberships within a domain. These tools can rapidly identify which accounts are members of high-privilege groups and where these accounts are active, facilitating attacks aimed at gaining elevated access and compromising critical assets.

Tracking Enumeration Activity with Event Logging

Prior to Windows 10 and Server 2016, detecting such enumeration activities through event logs was challenging, as there were no explicit events logged for these actions. However, with the introduction of advanced auditing features, administrators can now enable detailed logging for "Audit Security Group Management" and "Audit User Account Management" events. These logs provide insights into activities around group and account enumeration, offering an early warning system for potential attacks.

Event IDs and Investigation Focus

While the advanced auditing features generate a wealth of data, not all of it is immediately relevant to security investigations. To filter through the noise, investigators should concentrate on:

• Enumeration of sensitive groups and accounts.

• Accounts that are unlikely to perform legitimate enumeration activities.

• Unusual processes used for enumeration, such as PowerShell, WMI, or command-line tools.

Allowlisting common processes involved in legitimate enumeration activities can help reduce the volume of logs and highlight potentially malicious actions.

Implications and Mitigation

The ability to detect enumeration activities early in the attack cycle is a significant advantage. It allows organizations to respond to threats before attackers can leverage compromised credentials for further escalation or lateral movement. By monitoring for and analyzing these specific event IDs, security teams can identify suspicious behavior, investigate potential threats, and implement appropriate controls or mitigations to protect against unauthorized access and privilege escalation.

Conclusion

The enhancements in Windows 10 and Server 2016 event logging, specifically around group and account enumeration activities, represent a significant step forward in the detection and response capabilities available to defenders. Understanding and utilizing these logs is essential for maintaining a strong security posture, enabling early detection of reconnaissance activities, and mitigating threats before they can escalate into full-blown attacks.