In Windows, security principals (users, groups) are identified by aSecurity Identifier (SID), formatted as S-1---. TheRID (Relative Identifier)is the final component, unique within a domain or machine. For local accounts:
RID 500:Assigned to the built-inAdministratoraccount on every Windows machine (e.g., S-1-5-21--500).
Created during OS install, with full system privileges.
Disabled by default in newer Windows versions (e.g., 10/11) unless explicitly enabled.
RID 501:Guest account (e.g., S-1-5-21--501), limited access.
Technical Details:
Stored in SAM (C:\Windows\System32\config\SAM).
Enumeration: Tools like wmic useraccount or net user reveal RIDs.
Domain Context: Domain Admins use RID 512, but the question specifies a local machine.
Security Implications:RID 500 is a prime target for brute-forcing or pass-the-hash attacks (e.g., Mimikatz). CNSP likely advises renaming/disabling it (e.g., via GPO).
Why other options are incorrect:
A. 0:Reserved (e.g., Null SID, S-1-0-0), not a user RID.
C. 501:Guest, not Administrator.
D. 100:Invalid; local user RIDs start at 1000 (e.g., custom accounts).
Real-World Context:Post-compromise, attackers query RID 500 (e.g., net user Administrator) for privilege escalation.References:CNSP Official Study Guide (Windows Security); Microsoft SID Documentation.
