Attack Surface Determination: User Factors in Threat Modeling

User factors play a critical role in attack surface determination by accounting for how user access, behaviors, and roles impact organizational security. Within CompTIA SecurityX Objective 1.4, security professionals are tasked with understanding user-related vulnerabilities that could be exploited in an attack. The ways users interact with systems, manage credentials, and engage in daily tasks directly influence the security posture of an organization, and are thus integral to comprehensive threat modeling.

This article explores key user factors that contribute to the attack surface, including access management, user behavior monitoring, privilege controls, and secure onboarding and offboarding practices.

Importance of User Factors in Attack Surface Determination

Every user represents a potential entry point for attackers, whether through compromised credentials, improper access permissions, or insecure behaviors. Attack surface determination through user factors is essential because it allows organizations to:

• Identify Insider Threats: Both intentional and accidental user actions can compromise security.
• Control Privileged Access: Limiting privileged accounts reduces the risk of critical data exposure.
• Monitor Behavioral Indicators: User activity provides important signals about potential threats.

By addressing user factors, organizations can significantly reduce the likelihood of successful attacks stemming from misuse or compromise of user credentials.

User Access Management and Permissions

One of the most important aspects of managing user-related security is ensuring that access permissions are appropriate and limited. The goal is to implement least privilege principles, where users have only the permissions necessary for their roles.

Best Practices for Managing User Access

1. Implement Role-Based Access Control (RBAC)
   • Use RBAC to assign permissions based on user roles, ensuring that each user has access only to the resources necessary for their position.
   • Regularly review and update roles to align with any organizational or operational changes.
2. Use Multi-Factor Authentication (MFA)
   • Requiring MFA reduces the risk of unauthorized access, even if a user’s credentials are compromised.
   • MFA should be applied universally, especially to high-privilege accounts and any access points exposed to the internet.
3. Automate Provisioning and Deprovisioning
   • Automating the process of granting and revoking access for new hires, transfers, and terminations helps ensure permissions are managed accurately.
   • Immediate deprovisioning upon role change or termination is critical to prevent orphaned accounts from becoming entry points.

Monitoring and Managing User Behavior

Monitoring user activity provides insights into potential security issues arising from unintentional or malicious behavior. Behavior analysis is especially useful in detecting insider threats, where users with authorized access may act against organizational interests.

Techniques for Monitoring User Behavior

1. User Behavior Analytics (UBA)
   • UBA leverages machine learning to create behavioral baselines for each user, flagging unusual activity that deviates from these patterns.
   • Examples of suspicious behavior include accessing resources outside typical hours, attempting to access unauthorized files, or logging in from unusual locations.
2. Security Information and Event Management (SIEM)
   • SIEM systems aggregate and analyze log data from multiple sources, helping to correlate user actions with potential security incidents.
   • Regularly monitoring SIEM alerts can detect signs of compromise early, such as unexpected privilege escalations or large data transfers.
3. Monitor for Insider Threats
   • Use dedicated insider threat detection tools to focus on actions that may signal potential data exfiltration, fraud, or unauthorized system access.
   • These tools can alert security teams to behaviors like excessive file downloads, USB device use, or multiple failed login attempts.

Privilege Management and High-Risk User Accounts

Privileged accounts represent one of the most critical security risks within any organization, as they often have extensive access to sensitive data and system settings. Attackers frequently target privileged accounts due to the high level of control they provide.

Strategies for Privilege Management

1. Enforce Least Privilege
   • Restrict each user to the minimum permissions required to perform their job, especially for high-risk or privileged accounts.
   • Regularly review and adjust privileges based on role changes or evolving job requirements.
2. Implement Privileged Access Management (PAM)
   • PAM solutions provide additional security for privileged accounts by controlling and monitoring their use, particularly for critical systems and applications.
   • Use PAM to enforce session monitoring, just-in-time access, and automatic log-off after a period of inactivity.
3. Periodic Privilege Audits
   • Conduct regular audits of privileged accounts to ensure permissions are properly configured and consistent with organizational policies.
   • Audits help identify accounts that may no longer be necessary or those with excessive permissions, allowing for adjustments to minimize risks.

Secure Onboarding and Offboarding Processes

A secure onboarding and offboarding process is essential to maintaining a secure attack surface, as it ensures that users receive proper permissions initially and that these are revoked when no longer needed. Mismanagement in these areas often leads to orphaned accounts or access rights that outlast a user’s affiliation with the organization.

Onboarding and Offboarding Best Practices

1. Automate Account Creation and Deletion
   • Use an IAM solution to automate account creation, ensuring that users receive only the permissions needed for their roles.
   • Automated deletion upon termination helps eliminate inactive accounts that could be exploited.
2. Perform Access Reviews During Offboarding
   • Confirm that all user accounts, including those with third-party platforms, are deactivated.
   • Inventory devices and data storage assets issued to the departing user, ensuring that any residual access points, such as email forwarding or cloud storage links, are disabled.
3. Conduct Exit Interviews for Security Intelligence
   • Collect information during exit interviews regarding any security concerns or potential data handling practices that the employee observed.
   • These insights can help improve onboarding and offboarding protocols by identifying overlooked security risks or unauthorized access paths.

Conclusion

User factors in attack surface determination address a critical layer of organizational security. Managing access controls, monitoring behavior, securing privileged accounts, and enforcing rigorous onboarding and offboarding procedures help to prevent and detect unauthorized access, misconfigurations, and insider threats. This user-centric approach to threat modeling, aligned with Governance, Risk, and Compliance standards, strengthens the security posture and reduces the organization’s vulnerability to attacks.

Frequently Asked Questions Related to Attack Surface Determination and User Factors