A mission-critical system has been identified as having an administrative system account with attributes that prevent locking and change of privileges and name. Which would be the BEST approach to prevent successful brute forcing of the account?

ISACA CISM Exam syllabus in brief:

Information Security Governance    
A. Enterprise Governance
B. Information Security Strategy

Information Security Risk Management    
A. Information Security Risk Assessment
B. Information Security Risk Response

Information Security Program    
A. Information Security Program Development
B. Information Security Program Management

Incident Management    
A. Incident Management Readiness
B. Incident Management Operations