Windows Security Model Overview

Windows Security Model Overview

The Windows security model represents a sophisticated framework built on several foundational components working in concert. At its core, Windows uses a discretionary access control system where object owners determine access permissions. Every securable object in Windows, whether a file, registry key, or process, has an associated security descriptor containing access control information.

Security principals in Windows include users, groups, and computer accounts, each identified by a unique Security Identifier (SID). These SIDs remain constant even when account names change, providing consistent security tracking. The Local Security Authority (LSA) manages authentication and security policies, validating credentials and generating access tokens that define user privileges and group memberships.

Windows implements security through access tokens, which act as security badges for processes. When users log in, Windows creates an access token containing their SID, group SIDs, and privileges. Every process inherits or receives an access token, determining what resources it can access. This token-based system enables Windows to enforce security boundaries between different processes and users effectively.

The Windows security subsystem operates in kernel mode, providing protection from user-mode applications. Security Reference Monitor, a kernel component, enforces access control decisions for all object access attempts. This architecture ensures that security checks cannot be bypassed by user applications, maintaining system integrity even when running potentially malicious software.