Certified: The GIAC GISF Audio Course

In this episode, we’re going to build a mental picture of what a defensive technologies stack is and how it fits together, without getting lost in product names or complicated setup details. Beginners often hear terms like logs, telemetry, and alerts and imagine three separate piles of information with no clear purpose. The truth is that these are connected layers in a system that helps you notice suspicious activity, understand what it means, and respond before damage spreads. A defensive stack is not one tool, and it is not a shopping list. It is a set of capabilities that collect signals, enrich them with context, and turn them into decisions. If you understand the flow from raw evidence to a useful alert, you can reason about security more clearly, and you can also spot gaps when something important is missing. We will keep this practical and beginner-friendly by focusing on what each layer does and why it exists.

Before we continue, a quick note: this audio course is a companion to our course companion books. The first book is about the exam and provides detailed information on how to pass it best. The second book is a Kindle-only eBook that contains 1,000 flashcards that can be used on your mobile device or Kindle. Check them both out at Cyber Author dot me, in the Bare Metal Study Guides Series.

Start with the idea that computers constantly create evidence about what they are doing. Every login attempt, file access, network connection, and configuration change leaves traces, even if those traces are not always easy to see. Logs are one form of those traces. A log is a recorded event, usually written down as text-like data, that describes something that happened at a moment in time. Telemetry is a broader idea that includes logs but also includes measurements and signals that may be more continuous, more detailed, or more structured. Telemetry can include things like process activity on a device, network flow records, and security-relevant status signals that help you understand behavior over time. Alerts are what you get when you process logs and telemetry and decide that something is important enough to surface to a human or an automated response. The stack is the pipeline that turns raw traces into meaningful attention.

To build that stack mentally, it helps to imagine three roles that must be filled, even if one platform provides multiple roles. The first role is collection. If you do not collect the right evidence, you cannot detect the right problems. The second role is normalization and storage, which means you gather data from different places and make it comparable and searchable. The third role is detection and signaling, which means you apply rules or analytics to decide when something should be raised as an alert. If you skip collection, you are blind. If you skip normalization, you are drowning in incompatible formats. If you skip detection, you are staring at raw data all day with no prioritization. A strong defensive technologies stack does all three, and it does them in a way that supports the organization’s real risks, not just generic fear.

Collection begins with choosing what you want to observe. For beginners, a simple way to think about this is to follow the paths an attacker would use. Attackers interact with identities, devices, applications, data stores, and networks. That means your evidence needs to come from those same areas. Identity evidence includes authentication events, account changes, and permission changes. Device evidence includes process behavior, software installs, and system configuration changes. Application evidence includes access logs, errors, and unusual request patterns. Data evidence includes access to sensitive files and changes to storage permissions. Network evidence includes connections, destinations, and unusual traffic patterns. You do not need to collect everything, but you do need to collect enough to answer basic questions during an incident, such as who did what, from where, and with what result. If your stack cannot answer those questions, it will struggle under real pressure.

One of the most important beginner lessons is that logs and telemetry are only as useful as their context. A login event might show a username and a time, but without context you cannot tell whether it is normal or suspicious. Context includes things like which device the user normally uses, what locations are typical, what permissions the account has, and what the user’s job role requires. Context also includes asset information, like whether a system is a critical server or a test machine. This is why a defensive stack often includes enrichment, which means adding extra fields or labels to raw events so they become easier to interpret. Even a basic enrichment step can dramatically improve your ability to prioritize. For example, knowing that a login came from an administrator account is far more significant than knowing only that a login occurred. Context turns a pile of events into a story you can understand.

Normalization and storage might sound boring, but it is where many defensive stacks succeed or fail. Data comes in different shapes and languages. One system might record an I P address in one field name and another system might record it differently. Timestamps might be in different time zones or formats. Some systems might include rich details while others include only minimal information. If you cannot align these differences, you cannot easily connect related events across systems. Normalization is the process of turning diverse data into a consistent structure so that you can search and correlate it. Storage is about keeping the data available long enough to investigate, learn patterns, and meet any compliance requirements. For a beginner, the big idea is that security is often about connecting dots across time and across systems. If your stack makes it hard to connect those dots, your detection quality and investigation speed will suffer.

Once you have data collected and organized, you can start turning it into alerts, but alerts are not just louder logs. An alert should represent a decision that something deserves attention. That decision might be based on a clear rule, like multiple failed logins followed by a success, or it might be based on a more statistical approach, like behavior that is unusual compared to a baseline. Either way, the alert should be designed to support action. That means it should answer basic questions quickly, such as what happened, why it was flagged, what asset is involved, and what the likely impact could be. Beginners sometimes think the goal is to generate as many alerts as possible, as if more alerts means more security. In reality, too many low-quality alerts create fatigue and missed true issues. A good stack aims for fewer, better alerts that map to meaningful attacker behavior.

To understand how a stack evolves, it helps to think of maturity as moving from reactive to proactive. At first, many organizations rely on whatever logs are available by default and respond mainly after a problem is obvious. As the stack improves, collection becomes more intentional and aligned to specific threats. Detection becomes more behavior-based, meaning it looks for patterns that match attacker goals and techniques. Context and enrichment improve so that alerts become more accurate and easier to triage. Over time, the stack starts supporting not just detection but also prevention, because insights from logs and alerts can lead to stronger controls, better access policies, and safer configurations. You can think of the stack as a feedback loop. The better your visibility, the better your decisions, and the better your decisions, the more you can reduce risk before an attacker succeeds.

Another beginner misconception is that logs and telemetry are only useful for catching attackers, but they also help you understand normal operations. Knowing normal patterns is essential because many detections depend on the concept of unusual behavior. If you do not know what normal looks like, you cannot reliably recognize abnormal. Telemetry over time helps you establish that baseline. For example, if you learn that a server typically communicates with only a small set of destinations, then a new outbound connection pattern becomes more meaningful. If you learn that a user typically logs in during business hours from one region, then a midnight login from a distant location becomes more suspicious. This does not mean every unusual event is malicious. It means unusual events deserve a closer look, and your stack should make that closer look efficient, not exhausting. Baselines turn chaos into something you can reason about.

When you build a defensive technologies stack, you also need to think about coverage and gaps. Coverage means which parts of your environment produce useful evidence, and gaps are places where an attacker could operate with little visibility. Beginners often assume that if they have one central monitoring platform, they are covered everywhere. In reality, coverage can be uneven. Some devices might not send logs consistently. Some applications might have logging disabled or misconfigured. Some cloud services might require specific audit settings to record the events you care about. The stack is only as strong as its weakest blind spot, especially if that blind spot includes critical assets or privileged accounts. A helpful habit is to ask, if an attacker tried to steal credentials, move laterally, or exfiltrate data, what evidence would we have. If the answer is unclear, that is a sign of a gap, and gaps are where you prioritize improvements.

Alerts are only the visible tip of the iceberg, and this is important because new learners sometimes judge a stack by what pops up on the screen. Underneath every alert is a trail of supporting data. A high-quality alert should be connected to supporting logs and telemetry so that you can quickly validate it. If you cannot validate an alert, you might waste time on false positives, or you might miss real problems because the alert lacks detail. Validation is also how you improve. When you find out why an alert was wrong, you tune it so it becomes more accurate. When you find out why an alert was right, you may add related detections to catch earlier stages of the same behavior. Over time, the alert layer becomes a curated set of signals, not a constant flood. That is one of the clearest signs of a healthy stack.

Another key piece is understanding that different data types answer different questions. Identity logs tell you who is trying to access what. Endpoint telemetry tells you what is happening on a device. Network telemetry tells you how systems communicate and where data flows. Application logs tell you how services are being used and misused. Data access logs tell you when sensitive information is being touched. If you rely too heavily on only one type, you will miss certain attack paths. For example, if you have great network visibility but weak identity visibility, credential-based attacks may blend into normal traffic. If you have great endpoint visibility but weak application logging, abuse of web applications may appear only as normal-looking traffic. Building a stack is about blending these sources so that they reinforce each other. When one source is noisy or unclear, another source can confirm or contradict it, which improves confidence.

By the end of this lesson, you should see a defensive technologies stack as a flow, not a collection of disconnected tools. Logs and telemetry are the raw evidence and signals, collected from identities, endpoints, networks, applications, and data stores. Normalization and enrichment turn those signals into searchable, comparable events with context. Detections transform patterns in that data into alerts that are designed for action, not just attention. When the stack is healthy, it supports both fast response and steady improvement because every investigation teaches you what to collect next and what to detect better. The decision rule to remember is this: when you evaluate any defensive setup, ask whether it can reliably collect the right evidence, connect it across systems with context, and produce alerts that a person can validate and act on quickly.