Regular scanning of hard drives is the most effective way to detect installation of unauthorized software packages by employees because it can identify any software that is not approved by the organization and may pose a security risk or violate the software policy. Communicating the policy to employees is important, but it may not prevent or detect unauthorized software installation. Logging of activity on the network can monitor network traffic, but it may not capture all software installation events. Maintaining current antivirus software can protect the system from malicious software, but it may not detect all unauthorized software packages. References:
* ISACA, CISA Review Manual, 27th Edition, 2020, p. 2381
* ISACA, CISA Review Questions, Answers & Explanations Database - 12 Month Subscription

Comprehensive and Detailed Step-by-Step Explanation:
Toverify the effectivenessof a third-party provider'ssecurity controls, anindependent external audit reportis thestrongestevidence.
* Option A (Incorrect):Security configuration documentsare helpful butdo not confirm effectivenesswithout validation.
* Option B (Incorrect):Policies and procedures outlineintent, but anaudit confirms actual implementation.
* Option C (Correct):External audit reports (e.g., SOC 2, ISO 27001)provideindependent assurancethat security controls are effective.
* Option D (Incorrect):Management interviews providequalitativeinsights but arenot objective evidenceof control effectiveness.
Reference:ISACA CISA Review Manual -Domain 3: Information Systems Acquisition, Development, and Implementation- Coversthird-party risk assessments and audit assurance.

Social engineering exploits human vulnerabilities, and the most effective mitigation is training employees to recognize and respond to these threats. Security awareness programs help build a culture of vigilance, equipping employees with the knowledge to identify phishing attempts, suspicious behavior, and other social engineering tactics.
* Multi-factor Authentication (MFA) (Option A):Enhances access control but does not address the human vulnerability to social engineering.
* Access History Log Review (Option C):Useful for post-incident analysis but does not prevent incidents.
* File Encryption with Password Protection (Option D):Adds security layers but is ineffective if the password is compromised.
Reference:ISACA CISA Review Manual, Job Practice Area 4: Protection of Information Assets.

The best sampling method to use for verifying the adequacy of an organization's internal controls and being concerned about potential circumvention of regulations is B. Random sampling. Random sampling is a method of selecting a sample from a population in which each item has an equal and independent chance of being selected1. Random sampling reduces the risk of bias or manipulation in the sample selection, and ensures that the sample is representative of the population. Random sampling can be used for both attribute and variable sampling, which are two types of audit sampling that test for the occurrence rate or the monetary value of errors, respectively2.