The User Domain: Where Human Productivity Meets Machine Identity Risk

Part 2 of our 8-part series on enterprise Non-Human Identity attack surface

If you haven't read our overview analysis that introduced the six enterprise domains where NHIs operate, we recommend starting there for the full strategic context. This post dives deep into the User Domain—the digital workspace where your employees' daily activities create sprawling populations of machine identities with minimal oversight.

The Productivity Paradox

It's time to face the uncomfortable reality: every time your employees install an application, authorize an OAuth integration, or save credentials in their browser, they're creating Non-Human Identities that extend far beyond their individual access scope. The User Domain represents the digital workspace where employees interact with enterprise systems to perform daily functions such as web browsing, email communication, SaaS application usage, file sharing, and collaboration platforms.

Users Generate Machine Identities on a Weekly Basis

The security challenge is particularly acute because this domain operates under a fundamental tension: security controls must balance usability with protection. End-users regularly install applications, grant permissions, and store credentials without full understanding of the security implications. The domain's distributed nature, spanning corporate devices, BYOD endpoints, and cloud services—creates multiple attack vectors that traditional perimeter security simply can't address.

The Hidden NHI Population in Your User Environment

Most security teams drastically underestimate the machine identity population generated by user activity. Our analysis reveals that the average enterprise user generates multiple NHIs through routine productivity activities:

OAuth Applications: Users authorize third-party applications for productivity and integration purposes, often granting permissions that exceed their immediate needs. These authorizations create persistent access tokens that maintain enterprise access long after the original business need disappears.

Browser-Stored Credentials: Modern browsers automatically store API keys, session tokens, and authentication credentials, creating a distributed credential vault across thousands of endpoints with minimal governance.

SaaS Application Credentials: Individual users manage their own application-specific credentials across dozens of cloud services, each representing a potential entry point into enterprise systems.

Personal Access Tokens: Power users create personal access tokens for automation and integration purposes, often with broad permissions that span multiple business systems.

Risk Assessment: Moderate but Growing

We classify the User Domain as moderate risk based on our four-factor analysis framework, but the risk trajectory is concerning:

Attack Surface Size (Risk Factor): Every user generates multiple NHIs through daily activities, creating a massive and growing attack surface that scales with workforce size and digital adoption.

Social Engineering Susceptibility (Risk Factor): Users can be manipulated into granting excessive permissions to malicious applications, creating authenticated attack pathways that bypass traditional security controls.

Security Tooling Maturity (Mitigation Factor): CASB, EDR, Secure Browsers, and ZTNA tools are providing increasing visibility and control over user-generated NHIs, though coverage remains inconsistent.

Blast Radius Potential (Mitigation Factor): User-generated NHIs typically inherit the limited permissions of their creators, containing the scope of potential compromise compared to privileged service accounts.

Security Awareness (Mitigation Factor): Training programs increasingly address social engineering risks, though the complexity of modern OAuth permissions challenges even security-conscious users.

The Attack Patterns That Should Keep You Awake

The User Domain presents several unique attack vectors that exploit the intersection of human behavior and machine identity proliferation:

OAuth Consent Abuse

Attackers craft malicious applications that appear legitimate, social engineering users into granting excessive permissions. Once authorized, these applications maintain persistent access tokens with broad enterprise access, often remaining undetected for months or years.

OAuth Consent Abuse

Credential Harvesting

Malware on user endpoints can extract stored tokens and API keys from browsers and applications. Unlike traditional credential theft, these machine identities often lack the monitoring and rotation controls applied to human accounts.

Credential Harvesting

Shadow IT Proliferation

Unmanaged application installations create ungoverned access pathways that bypass corporate security controls. These applications often require elevated permissions and create long-lived access credentials outside IT oversight.

Token Persistence

OAuth tokens and API keys often remain active indefinitely, providing long-term access even after business needs change. Unlike human accounts, these machine identities rarely have expiration dates or recertification requirements.

Token Persistence

Current State: Better Tools, Same Problems

The good news is that security tooling for the User Domain is improving rapidly. CASB solutions provide visibility into SaaS application usage, EDR platforms can detect credential theft, and Zero Trust Network Access tools enable granular access controls. Secure browsers are beginning to isolate credential storage, and some organizations are implementing OAuth application approval workflows.

However, these technical improvements haven't addressed the fundamental challenge: users continue to operate with significant autonomy in credential creation and management. The distributed nature of modern work—spanning multiple devices, locations, and cloud services—makes centralized control increasingly difficult.

Strategic Recommendations for User Domain Security

Based on our analysis of successful enterprise implementations, we recommend a three-pronged approach:

1. Visibility and Discovery

Implement comprehensive scanning across all user endpoints and cloud services to identify OAuth applications, stored credentials, and shadow IT installations. Many organizations are shocked to discover they have 10-50 times more user-generated NHIs than they estimated.

2. Governance Without Friction

Deploy approval workflows for high-risk OAuth applications while maintaining user productivity. Focus controls on applications requesting broad permissions or sensitive data access, rather than creating bottlenecks for routine productivity tools.

3. Automated Risk Assessment

Implement behavioral monitoring that can distinguish between normal and suspicious credential usage patterns. Unlike human users, machine identities follow predictable patterns that make anomaly detection highly effective.

The Business Impact You Can't Ignore

User Domain NHI compromises create unique business risks because they often provide authenticated access that appears legitimate to security monitoring systems. When a compromised OAuth application begins accessing enterprise data, it's using credentials that were legitimately granted by authorized users.

This creates several concerning scenarios:

• Data Exfiltration: Compromised productivity applications can access and extract sensitive business information
• Lateral Movement: OAuth tokens often provide access to multiple connected systems and services
• Compliance Violations: User-authorized applications may access regulated data without appropriate controls
• Long-term Persistence: Unlike traditional breaches, OAuth-based access can continue indefinitely without triggering security alerts

What's Coming Next

The User Domain's risk profile is evolving rapidly as AI-powered applications and automation tools become integral to knowledge work. These applications typically require broad permissions to access user data and perform actions on behalf of employees, dramatically expanding the potential blast radius of compromise.

In our next post, we'll examine the Corporate IT Domain—the operational backbone that, despite decades of security investment, still harbors significant NHI risks in legacy systems and infrastructure components. We'll explore how traditional enterprise security models are adapting to address machine identity sprawl in established IT environments.

About this series: This week-long exploration examines how business functions create NHI attack surfaces and provides actionable frameworks for security leaders who need to balance business enablement with risk management, based on comprehensive analysis of enterprise domains, attack patterns, and strategic risk assessment.