Certified: The ISACA CISA Prepcast

Welcome to The Bare Metal Cyber CISA Prepcast. This series helps you prepare for the exam with focused explanations and practical context.
Digital forensics is the discipline of identifying, collecting, analyzing, and preserving electronic evidence in a manner that supports investigation, litigation, policy enforcement, and internal accountability. It is an essential capability for any organization that may experience a security incident, internal policy violation, or data breach. Forensics provides the detail necessary to understand what happened, who was involved, how systems were accessed, and what data was affected. The process must follow strict protocols to ensure that evidence is defensible, especially if it may be used in court or regulatory proceedings. Evidence that is poorly handled, modified, or undocumented can become legally inadmissible and undermine the entire investigative effort. The CISA exam often includes questions about forensic readiness, evidence handling, and chain of custody. As an auditor, you are responsible for verifying not just that the organization can collect evidence, but that it can do so in a controlled, consistent, and legally sound manner.
Core principles govern every stage of the digital forensic process. Preservation means ensuring that data is not altered during investigation or analysis. This includes making exact copies of evidence before any examination begins. Identification involves determining where digital evidence may exist—whether in system logs, email archives, or volatile memory. Collection refers to the acquisition of this evidence using approved tools and methods that prevent tampering. Examination and analysis then allow investigators to uncover meaningful patterns, detect malicious activity, and reconstruct timelines. Finally, documentation and reporting ensure that findings are clearly communicated and that every action is traceable. Each of these principles supports a key control objective: to enable the organization to understand incidents while preserving legal defensibility. CISA candidates must understand how each principle supports reliable evidence handling and should expect questions about procedural integrity throughout the forensic lifecycle.
Digital evidence can come from a wide range of sources, and auditors must assess whether those sources are monitored, retained, and accessible. System logs include records of user activity, authentication attempts, application events, and network traffic. Access logs track who entered a system, what files were accessed, and what changes were made. Application audit trails can capture user actions in sensitive platforms like ERP systems or databases. Disk images preserve the state of storage media at a particular point in time, while memory captures can reveal real-time activity, including malicious processes or stolen credentials. Email archives, browser history, and USB usage records can all shed light on intent and access behavior. Cloud services and mobile devices also store valuable data, including session history, chat logs, and app activity. For auditors and exam candidates, the key is knowing whether the organization collects data from all relevant sources and whether that data is retained long enough to support investigation.
Chain of custody is a critical procedural safeguard that tracks who accessed evidence, when, and for what purpose. From the moment evidence is collected, the organization must be able to prove that it remained unaltered, untampered, and in the custody of authorized individuals. This is especially important if evidence may be presented in court. Chain of custody documentation includes timestamps, signatures, transfer records, and the rationale for access or handling. Breaks in the chain—or the inability to produce records—can result in evidence being excluded from legal proceedings. Forensic readiness means having procedures in place to log and protect evidence from the start. CISA scenarios may include chain of custody failures or audit findings related to improper access control over forensic data. Auditors evaluate whether chain of custody is enforced consistently, and whether staff understand how to document evidence transfers in a way that preserves admissibility.
Forensic imaging and acquisition are the foundational techniques used to collect data without altering the original source. Imaging tools such as FTK Imager or EnCase are used to create exact bit-for-bit copies of storage devices. These images allow analysts to examine a system’s contents without touching the original media. Hash values are calculated before and after imaging to prove that the image is an exact duplicate and has not been modified. The original media must be secured in a tamper-proof location, preferably with encryption and access logging. Evidence should be clearly labeled, and imaging logs must include timestamps, source information, and hash values. Auditors check for the presence of imaging reports, verify that hash verification was performed, and ensure that no analysis was conducted on original drives. On the CISA exam, candidates should recognize why imaging is necessary, how to validate evidence integrity, and how poor acquisition practices can compromise investigations.
Live forensics focuses on capturing data from systems that are running, especially volatile information that is lost when a device powers down. This includes random-access memory, active processes, open network connections, logged-in users, and command history. Live forensics is particularly important when investigating fileless malware, credential theft, or insider activity in real time. Tools such as Volatility, GRR, or Belkasoft can extract and preserve this data before it disappears. However, live forensics must balance speed and precision—collecting data without triggering further damage or contamination. In some cases, shutting down a device may be the safest option, while in others, it could destroy critical evidence. CISA candidates must understand when live forensics is appropriate, what types of evidence are at risk, and how to minimize intrusion during collection. Auditors evaluate whether organizations are prepared to capture volatile data and whether procedures address preservation without unnecessary risk.
Analysis is where evidence becomes insight. Analysts examine file systems to find deleted files, timestamp inconsistencies, or hidden directories. They correlate logs across devices to map attacker movement, detect data staging, and identify persistent backdoors. Reconstructing communications from email, chat logs, or mobile apps may reveal exfiltration attempts or internal coordination. In more advanced cases, forensic teams may perform malware reverse engineering to determine how code behaves, what systems it targets, and how it was delivered. Forensic environments must be isolated to prevent cross-contamination. All findings must be repeatable, documented, and verifiable. Auditors assess whether analysts used validated tools, maintained documentation of every step, and preserved the evidence trail. On the exam, CISA candidates should be familiar with typical forensic tasks and know how to evaluate whether findings are based on objective analysis rather than speculation or guesswork.
Reporting is how forensic teams communicate what they discovered, how they discovered it, and what it means. Reports must be written in a clear, structured format that supports legal, executive, and technical audiences. A well-written report includes a timeline of events, a list of affected systems, descriptions of attacker activity, and evidence supporting each conclusion. Reports should avoid speculation and focus on presenting evidence objectively. Supporting materials such as screenshots, log extracts, or tool output should be attached or referenced. Inconsistent reporting, missing evidence, or vague conclusions can undermine the credibility of the entire investigation. CISA candidates may be asked how to write or audit forensic reports, especially in cases where technical detail must support legal claims or executive decisions. Auditors review report structure, clarity, and completeness to ensure that findings are well documented and defensible.
Legal and regulatory considerations shape how forensic investigations are conducted and reported. Privacy laws govern what data can be collected and how it must be protected. Jurisdictional issues may arise when data is stored in another region or managed by a third party. Breach notification laws require specific timelines and documentation. Chain of evidence and admissibility rules vary by country, but most require procedural consistency and defensible handling. Before initiating certain actions—such as accessing employee emails, imaging workstations, or reviewing logs—organizations must consult with legal, human resources, and compliance teams. Failure to do so may violate employee privacy rights or contractual agreements. Auditors assess whether legal oversight is built into forensic workflows, whether documentation supports legal use, and whether staff understand the boundaries of acceptable evidence collection. CISA exam scenarios may involve legal missteps, and candidates must be prepared to identify risks and recommend controls that preserve both evidence and compliance.
For CISA candidates, understanding digital forensics requires more than knowing how to collect logs or create disk images. You must be able to evaluate whether the organization is prepared to respond to an incident with accuracy, integrity, and legal defensibility. Expect exam questions on chain of custody, live forensics, reporting, and how to assess forensic readiness. You may be asked to identify weaknesses in evidence handling or evaluate the effectiveness of forensic analysis and documentation. As an auditor, your role is to ensure that the organization can gather digital evidence in a way that supports both incident response and legal accountability. Forensics is not just a technical task—it is a controlled process that connects security events to facts and outcomes. A strong forensic capability accelerates response, improves clarity, and ensures that when questions arise, the answers are backed by verifiable evidence.
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