The absence of audit logging is the greatest concern because it represents a fundamental failure of accountability and traceability. In a shared system like a CRM, which contains sensitive customer data, it is critical to know who accessed or modified information and when. Without audit logs, it is impossible to detect unauthorized activities, investigate security incidents, or hold individuals accountable for their actions. This lack of a detective and deterrent control undermines the entire access control structure, rendering other controls less effective.

A. The absence of single sign-on is an inconvenience and a potential efficiency loss, but not a critical failure if other authentication controls are strong.

C. An inconsistent security baseline is a significant risk, but its impact may be localized, whereas the lack of logging affects accountability across the entire system.

D. Not requiring complex passwords is a serious vulnerability that increases the risk of unauthorized access, but the lack of logging makes it impossible to even detect or investigate such an access.

1. ISACA

CISA Review Manual

27th Edition. Chapter 4

Section 4.5.3

"Monitoring and Log Management." The manual states

"Logs are records of events that have occurred on a system. They are important for establishing accountability

reconstructing events

detecting intrusions and problem-solving." It further explains that without logs

"it may be impossible to determine...the extent of an intrusion." This highlights that a lack of logging is a critical failure in security monitoring and accountability.

2. ISACA

CobiT 5: Enabling Processes. APO12

Manage Risk

and DSS05

Manage Security Services. Specifically

DSS05.07

"Monitor the infrastructure for security-related events

" emphasizes the need to collect and analyze security logs to identify malicious activity and incidents. The absence of logging makes this entire control practice impossible to implement.

3. Purdue University

"Information System Auditing" Courseware. In modules discussing logical access controls

the principle of accountability is stressed as a cornerstone. Audit trails (logs) are presented as the primary mechanism for enforcing accountability by creating a record of user actions that can be traced back to a specific individual. (Reference to general principles taught in such courses

e.g.

Purdue Global IT 540).

A voltage regulator is a device specifically designed to automatically maintain a constant voltage level. In an environment susceptible to unexpected increases in power, such as voltage surges or spikes, a voltage regulator actively conditions the incoming power. It suppresses excessive voltage and boosts insufficient voltage, ensuring that the connected system receives a stable and clean power supply. This direct management of voltage fluctuations makes it the most effective protective measure against the specific threat described, preventing damage to sensitive electronic components.

A. A generator is a backup power source used during a complete power failure (blackout); it does not protect against fluctuations from the primary power line.

C. A circuit breaker is a safety device that interrupts current flow during an overload or short circuit, primarily protecting against fire hazards, not voltage spikes.

D. An alternate power supply line provides redundancy for power availability but offers no inherent protection against power quality issues like surges affecting the grid.

1. ISACA CISA Review Manual

27th Edition. Domain 4: Information Technology Operations

Section 4.4.1 Hardware Maintenance and Monitoring. The manual states

"Power conditioners and surge protectors should be used to protect against power fluctuations... An uninterruptible power supply (UPS) provides short-term backup power from batteries... and also provides protection against power surges." A voltage regulator is a primary type of power conditioner.

2. National Institute of Standards and Technology (NIST) Special Publication 800-53

Revision 5. Security and Privacy Controls for Information Systems and Organizations

Control PE-11: Alternate Power Equipment. The discussion notes mention the use of "power line conditioners" as a control to ensure stable power for systems

distinguishing them from sources like generators which address outages.

3. Kizza

J. M. (2017). Guide to Computer Network Security. Springer. Chapter 12: Physical and Environmental Security. Section 12.2.2 Power Supply. The text explains that "power conditioners

including voltage regulators and surge suppressors

filter the power

protecting equipment from spikes

surges

and noise." This directly supports the function of a voltage regulator in protecting against power increases. (DOI not applicable for entire book

but concept is standard in academic texts on this topic).

Data architecture provides the most comprehensive information for understanding a transaction audit trail. It defines the structure, relationships, and management of all data within the application, including how transaction data is captured, stored, and linked to user activities, timestamps, and other relevant events. This holistic blueprint allows an IS auditor to understand the entire lifecycle of a transaction's data, which is the essence of an audit trail, rather than just viewing a single process or file structure in isolation.

A. System/process flowchart: This illustrates the flow of operations but lacks the specific detail about the data elements that are captured and stored in the audit trail.

B. File layouts: This is too specific, as it only describes the structure of flat files. Modern online applications typically use databases, and this option would not describe the relational structure.

D. Source code documentation: This provides a highly granular, implementation-level view. It is inefficient for an auditor to review code to understand the overall audit trail design and data relationships.

1. ISACA

CISA Review Manual

27th Edition

2019. Domain 3: Information Systems Acquisition

Development

and Implementation

Section 3.3.5 Data Files

states the importance of understanding the "application system’s data structure and file organization" to test application controls. Data architecture documentation provides this comprehensive view

which is essential for evaluating the completeness and accuracy of an audit trail.

2. Spewak

S. H.

& Hill

S. C. (1992). Enterprise Architecture Planning: Developing a Blueprint for Data

Applications

and Technology. While a foundational text

its principles are core to IS audit. Chapter 3

"Data Architecture

" explains that this architecture defines the major kinds and types of data and their interrelationships. An audit trail is a kind of data

and its relationship to transaction data is defined within the data architecture.

3. Zachman

J. A. (1987). A framework for information systems architecture. IBM Systems Journal

26(3)

276-292. The Zachman Framework

a seminal work in enterprise architecture

defines the "Data" column (the "What") as a core component of understanding a system. An audit trail is fundamentally about data—what happened

what data was affected

etc. The data architecture provides this perspective

detailing the entity-relationship models necessary to trace transactions. (DOI: 10.1147/sj.263.0276)

The most critical factor in the validity and reliability of any machine learning (ML) model is the quality of the data used for its training. The principle of "Garbage In, Garbage Out" (GIGO) is fundamental here. If the training data is sourced from an unreliable provider, it may be inaccurate, biased, or incomplete. This foundational flaw will be learned and amplified by the model, rendering its predictions untrustworthy, regardless of how well it is designed or tested. An IS auditor's primary concern is to ensure the integrity and reliability of the system's foundation, which for an ML model, is its training data.

A. A decrease in accuracy on a different population indicates a generalization problem, which is a concern, but it is a performance symptom, not a foundational flaw like unreliable source data.

C. The use of open-source programming languages (e.g., Python, R) is a standard, accepted, and prevalent practice in ML development and does not represent an inherent risk.

D. Testing a model with a holdout dataset drawn from the same population as the training data is a correct and standard procedure for validating model performance.

1. ISACA

"Auditing Artificial Intelligence" White Paper

2019: Page 13

under the "Data" section

states

"The quality of the data used to train the AI system is critical to its performance... The GIGO (garbage in

garbage out) principle applies. If the data used to train the system is biased

incomplete or of poor quality

the system will not perform as expected." This directly identifies data quality and source as a critical audit concern.

2. Munoko

I.

Brown-Liburd

H. and Vasarhelyi

M. "Auditing machine learning models: A framework for auditors and data scientists." Managerial Auditing Journal

Vol. 35 No. 5

2020

pp. 649-667: In Section 3.1

"Data Understanding

" the framework emphasizes that a key audit step is to "assess the reliability of the data source" and evaluate the data collection process to ensure data quality. This highlights the primacy of the data source in an ML audit. (DOI: https://doi.org/10.1108/MAJ-08-2019-2382)

3. ISACA

"A Framework for Auditing AI

" ISACA Journal

Volume 6

2019: The article outlines an audit approach where a primary step is to "understand and assess the data used by the AI." It specifies that the "auditor should verify the source

lineage and quality of the data

" reinforcing that the data's origin is a top-priority audit point.

During the planning phase of acquiring any new system, especially a cloud-based platform, the most critical initial determination is the classification of data that will be stored and processed. This decision is foundational as it directly influences all other security, compliance, and operational considerations. Understanding the data's sensitivity (e.g., public, confidential, restricted) dictates the required level of security controls, data residency and sovereignty requirements, and applicable legal or regulatory obligations (e.g., GDPR, HIPAA). This strategic decision precedes and informs the tactical design of access controls, user lifecycle management, and auditing procedures.

A. Role-based access control (RBAC) policies are a specific security control mechanism. The design and stringency of these policies are a direct consequence of the types of data the platform will manage, not the primary planning decision.

C. Processes for on-boarding and off-boarding users are operational procedures. While crucial for security, they are defined and implemented based on the security requirements established from the data classification and risk assessment.

D. Processes for reviewing administrator activity are a detective control. The need for and frequency of such reviews are determined by the risk level associated with the platform, which is primarily defined by the sensitivity of the data it holds.

---

1. ISACA

CISA Review Manual

27th Edition. Domain 4: Information Systems Operations and Business Resilience

Section 5.3.3 Data Classification. The manual emphasizes that data classification is a prerequisite for applying appropriate security controls. It states

"The objective of classifying information is to ensure that information assets receive an appropriate level of protection." This principle is most critical during the initial planning and requirements definition phase of an acquisition.

2. NIST Special Publication 800-144

Guidelines on Security and Privacy in Public Cloud Computing. Section 5.2.1

"Information and Data

" states

"The type of information processed

stored

and transmitted by a system is a primary factor in determining the security and privacy requirements for the system." This highlights that understanding the data is the foundational first step in planning for cloud adoption.

3. COBIT 2019 Framework: Governance and Management Objectives

ISACA. The management objective APO14 Managed Data includes the key practice APO14.02

"Define and maintain a data classification scheme." The framework guidance indicates that this classification

based on business needs and criticality

is essential to "allow for the application of appropriate controls." This is a fundamental governance activity that must be addressed in the planning phase.

According to established incident response frameworks, the phase immediately following the detection and analysis of an incident is containment. The primary objective of the containment phase is to stop the incident from spreading and to limit its impact on business operations and data. By focusing on limiting the damage, the incident response team takes immediate, necessary actions—such as isolating the affected network subnet—to prevent the virus from propagating further. This step is critical and must be performed before any attempts at eradication or recovery to ensure the problem does not escalate.

A. Verifying that the compromised systems are fully functional is a step within the recovery phase, which occurs after the threat has been contained and eradicated.

C. While documentation is a continuous process, the immediate tactical priority after identifying an outbreak is containment, not comprehensive documentation.

D. Removing the virus (eradication) and restoring systems (recovery) are subsequent phases that should only be initiated after the incident has been successfully contained.

1. Cichonski

P.

Millar

T.

Grance

T.

& Scarfone

K. (2012). Computer Security Incident Handling Guide (NIST Special Publication 800-61

Rev. 2). National Institute of Standards and Technology. Section 3.3

"Containment

Eradication

and Recovery

" states

"Containment is the first step in this phase... Containment is important before an incident overwhelms resources or increases damage." (p. 26). https://doi.org/10.6028/NIST.SP.800-61r2

2. ISACA. (2019). CISA Review Manual

27th Edition. Domain 4: Information Systems Operations and Business Resilience. The manual outlines the incident management process

emphasizing that after detection and analysis

the immediate response is to contain the incident to limit the extent of the damage.

3. Carnegie Mellon University Software Engineering Institute. (2017). CSIRT Services. "Containment: Limiting the scope and magnitude of the event." This is listed as a primary service and a critical step in the incident handling process

following initial analysis. Retrieved from https://resources.sei.cmu.edu/assetfiles/WhitePaper/2017019001503734.pdf (p. 5).

The primary risk in this scenario is the inaccurate manual transcription of totals from a source document (spreadsheet) to a target system (job-costing system). Reconciliation is a detective control that directly addresses this risk by comparing the totals from the source with the totals entered into the system. This control provides the highest level of assurance that the overall data transfer was accurate and complete. While other controls are useful, reconciliation is the most effective method for verifying that the final, aggregated figures in the system match the source.

B. Validity checks only ensure the correct data type is entered (e.g., numeric vs. character) but do not verify the accuracy of the number itself.

C. Reasonableness checks only confirm that an entered value falls within a plausible range, not that it precisely matches the source document.

D. Displaying entered data for visual verification is a weak control because it relies on the data entry person to notice their own error.

1. ISACA. (2019). CISA Review Manual

27th Edition. Schaumburg

IL: ISACA. In Domain 3: Information Systems Acquisition

Development

and Implementation

the section on Application Controls describes reconciliation as a key control to "ensure that data is complete and accurate throughout its processing." It specifically contrasts this with input controls like validity and reasonableness checks

which are preventive but do not guarantee accuracy against a source document.

2. Weber

R. (2012). Information Systems Control and Audit. Pearson. Chapter 12

"Auditing Computer Applications I

" explains that while input validation controls (like validity and reasonableness checks) are important preventive measures

detective controls such as reconciliations are essential for ensuring the accuracy and completeness of data that has been processed. Comparing source data totals to processed totals is presented as a fundamental reconciliation technique.

3. Singleton

T. (2013). IT Auditing and Application Controls for Small and Mid-Sized Enterprises. ISACA Journal

Volume 5. This article emphasizes that for manual data entry processes

reconciliations are a critical compensating control to detect errors that preventive input controls may miss

thereby ensuring data integrity between different stages of processing.

The best indication that a project is on track is the successful completion of critical, late-stage milestones within the planned schedule. User acceptance testing (UAT) is one of the final phases before implementation. Successfully identifying and addressing issues discovered during UAT prior to the original go-live date demonstrates that the project has progressed through development and earlier testing phases on time and is effectively managing the final pre-deployment activities. This provides tangible evidence of progress and readiness, unlike planning or communication activities, which do not reflect the project's actual status.

A. This is an essential early-stage planning activity. Completing it does not guarantee that subsequent development and testing phases will remain on schedule.

B. Documenting due dates is part of the initial project plan. It represents the intended schedule, not the actual progress against that schedule.

D. Communicating a go-live date is a project management task, not an indicator of progress. The project could be significantly behind schedule despite this communication.

1. ISACA

CISA Review Manual

27th Edition (2019)

Domain 3: Information Systems Acquisition

Development

and Implementation

Section 3.4.5 Testing. This section details the different levels of testing

positioning User Acceptance Testing (UAT) as the final phase of testing to ensure the system is acceptable to the end users before it is placed into production. Successful resolution of UAT issues is a critical gate for implementation

making it a key indicator of project readiness and adherence to schedule.

2. ISACA

CISA Review Manual

27th Edition (2019)

Domain 2: Governance and Management of IT

Section 2.6 Project Management. This section emphasizes the importance of monitoring and controlling project performance by measuring progress against the project plan. The successful completion of a major milestone like UAT is a primary metric for assessing whether a project is on track.

3. McConnell

S. (2004). Code Complete: A Practical Handbook of Software Construction (2nd ed.). Microsoft Press. Chapter 20

"The Software-Quality Landscape." While not an ISACA-specific source

this foundational software engineering text is widely used in university curricula. It discusses the importance of late-stage testing (like UAT) in validating software quality and readiness for release. The rate of defect discovery and resolution during this phase is a key indicator of project health and proximity to completion.

The IS auditor's conclusions must be based on sufficient, reliable, and relevant evidence gathered through independent testing. When management provides new evidence after the initial fieldwork but before the final report is issued, the auditor has a professional responsibility to validate this new information. Simply accepting management's assertion or evidence without verification would compromise the auditor's objectivity and due professional care. Therefore, the best course of action is to re-perform the specific audit tests related to the control in question. This allows the auditor to independently verify that the control has been implemented and is operating effectively, ensuring the final audit report is accurate and based on verified facts.

A. Explaining that the control will be evaluated during follow-up is a viable option, but not the best, as it results in a report that does not reflect the most current, verifiable state of the control environment.

C. Changing the conclusion based solely on evidence provided by management, without independent verification, is a violation of professional standards for objectivity and due care.

D. Adding comments about management's action is a good reporting practice, but it is insufficient. The auditor must first validate the claim before modifying the report's primary conclusion on the control's effectiveness.

---

1. ISACA

ITAF: A Professional Practices Framework for IS Audit/Assurance

4th Edition

2020.

Guideline 2204 Evidence

Section 2204.3 Evaluation of Evidence: States

"IS auditors should evaluate the evidence gathered to determine whether it is sufficient and appropriate to support the conclusions to be drawn." This implies that evidence from management must be evaluated by the auditor

which is best done through re-performance of tests.

Guideline 2401 Reporting

Section 2401.8 Subsequent Events: Notes that the IS auditor should consider the effect of events occurring between the end of fieldwork and the date of the report. If management implements a control in this period

the auditor should perform procedures to determine the effect of this event on the findings and report. Re-testing (re-performing the audit) is the appropriate procedure.

2. ISACA

CISA Review Manual

27th Edition

2019.

Chapter 1: The Process of Auditing Information Systems

Section 1.4.4

"Reporting/Communication of Results": This section emphasizes that all audit findings must be supported by sufficient and appropriate evidence. If new evidence is presented that contradicts a finding

the auditor must re-evaluate. The most rigorous method of re-evaluation is to re-test the control. The manual states

"The IS auditor should obtain sufficient and appropriate evidence to draw reasonable conclusions on which to base the audit results." Accepting management's evidence without re-performance would not meet this standard.

Data classification is a fundamental component of a risk-based information security program. The BEST source for determining the appropriate classification for new data is a risk assessment. This process evaluates the data's value, sensitivity, and criticality by analyzing the potential impact (e.g., financial, operational, reputational, legal) on the organization if its confidentiality, integrity, or availability were to be compromised. The outcome of this impact analysis directly informs the assignment of a classification level (e.g., Confidential, Restricted), which in turn dictates the necessary security controls.

A. Input by data custodians: Data custodians are responsible for implementing and maintaining security controls, not for determining the classification level, which is the responsibility of the data owner.

B. Security policy requirements: The security policy establishes the framework and defines the available classification levels, but it does not determine the specific classification for a particular data set.

D. Current level of protection: The classification of data should dictate the required level of protection, not the other way around. Basing classification on existing controls is a reactive and flawed approach.

1. ISACA

CISA Review Manual

27th Edition. Domain 3: Information Systems Acquisition

Development

and Implementation

Section 3.4.3 Data Classification. The manual explains that data classification is based on the data's criticality and sensitivity to the organization

which are key outputs of a risk assessment process.

2. ISACA

"Data Classification: A Prerequisite for Effective Information Protection and Governance

" White Paper

2019. Page 4 states

"The classification of data is based on its level of sensitivity and the impact to the organization should that data be disclosed

altered or destroyed without authorization." This impact assessment is the core of a risk assessment.

3. National Institute of Standards and Technology (NIST)

Federal Information Processing Standards (FIPS) Publication 199

"Standards for Security Categorization of Federal Information and Information Systems

" February 2004. Section 2

"Purpose

" and Section 3.1

"Security Categorization

" specify that the categorization (classification) of information is determined by assessing the potential impact of a loss of confidentiality

integrity

or availability. This is a foundational activity within risk management.