The CTEM Chronicles: Validation, Where Risk becomes Real

By
Victor Marchetto
,
Manager, Advisory Services
Contents

Introduction: Testing the threats that made the cut

You’ve done the hard work. You’ve mapped your assets, uncovered threats, and filtered the noise down to a handful of high-priority exposures. But now you’re stuck on the same question that stops most teams at this stage:

“Are these exposures actually exploitable, or are they just theoretical risks?”

This is a critical moment in the CTEM process. Acting on something that isn’t a real threat wastes time, drains resources, and risks losing momentum. Ignoring something that is a real risk, on the other hand, could make for a bad day.

This is what makes Phase 4, Validation, so important. It is the step that separates assumptions from verified risk. Without it, the CTEM cycle is incomplete.

In this episode, you will learn how to practically test your prioritized exposures, avoid common pitfalls, and use the results to strengthen your security position.

Let’s make sure your list of risks is grounded in reality and not just theory.

Quick Recap: CTEM Phases 1 to 3

Before jumping into validation, let’s quickly retrace how we got here.

In Phase 1: Scoping, you defined what part of the organization you were analyzing. Whether it was a single business unit, a specific application, or a broader network segment, you narrowed the focus to ensure clarity and relevance.

Then in Phase 2: Discovery, you mapped out the assets within that scope. That included everything from known infrastructure to shadow IT, anything an attacker could potentially interact with.

Phase 3: Prioritization involved identifying which vulnerabilities or misconfigurations mattered most. You filtered out low-impact issues and noise, focusing only on exposures that were both relevant and potentially damaging to your scoped environment.

Now, in Phase 4: Validation, the aim is to confirm whether those prioritized exposures can actually be exploited. This is where theoretical risk meets practical testing.

What Phase 4: Validation Really Means

Validation is where you stop guessing and start proving. It is the act of testing whether a prioritized exposure is genuinely exploitable in your specific environment.

This is not just running a vulnerability scan or handing the job off to a red team. It’s a targeted effort to confirm risk based on your scope, your assets, and your threat model.

It answers questions like:

  • “Can this misconfiguration actually be exploited in the wild?”
  • “Will this vulnerability lead to meaningful impact if triggered?”
  • “Is this a real risk, or is it just noisy telemetry?”

Validation bridges the gap between theoretical and real-world exposure. It provides the evidence that security teams and stakeholders need to make confident, informed decisions.

Keep asking yourself “Can an attacker really do something with this?”

This level of clarity helps you avoid wasting time on false positives and keeps the CTEM loop grounded in reality.

Step 1: Prepare Your Validation Plan

Before launching any tests, you need a plan. Rushing into validation without structure increases the risk of missteps, like triggering unnecessary alerts, disrupting production systems, or drawing the wrong conclusions.

1. Define Your Success Criteria

What outcome are you trying to prove? Are you trying to establish access to sensitive data, lateral movement, or privilege escalation? Clear goals will guide your test logic and help you decide whether an exposure is genuinely exploitable.

2. Map Out Your Testing Environment

Decide where validation will happen: production, staging, or an isolated lab. Each option has trade-offs.

  • Lab environments are safer but may miss real-world conditions.
  • Staging environments strike a balance but can lack complete parity.
  • Production environments offer the most accurate data, but carry higher risk.

Pick the environment that gives you the confidence you need without disrupting business operations.

3. Assign Roles and Permissions

Who is running the tests? Who needs to be informed? Who signs off on actions that may trigger alerts or affect systems?

Alignment here avoids confusion and ensures everyone knows what’s in scope and what’s off-limits.

Step 2: Choose Your Validation Techniques

Not all exposures are equal, and neither are the methods to validate them. The technique you use should fit the nature of the exposure, the environment you’re working in, and the level of assurance you need.

Validation Techniques Description
Proof-of-Concept Testing Use a known exploit or a simplified version to confirm whether the vulnerability can be triggered under controlled conditions.
Manual Exploration Think like an attacker to test complex scenarios or chained vulnerabilities. Use this when automation can’t simulate nuance.
Simulated Attacks Mimic attacker behavior in a safe, structured way. Useful for understanding real impact and testing response.
Automated Validation Tools Good for scale and speed, but not a replacement for context. Use them to complement manual work, not substitute it.

Step 3: Execute the Tests

1. Stick to the Scope

Focus on exposures prioritized in Phase 3. Avoid chasing low-risk distractions or noise.

2. Replicate the Attacker’s Path

Test from the attacker’s point of view. Follow realistic access paths and user roles to see how far an exploit can go.

3. Watch for System Reactions

Note any alerts, triggers, or access restrictions. These indicators show whether security layers are already in place.

4. Record Everything

Capture what you tested, how you did it, and what you observed. This sets you up for clear analysis in the next step.

Step 4: Assess and Document Findings

1. Categorize the Outcome

Label each test as:

  • Confirmed Exploitable
  • Not Exploitable in Current Context
  • False Positive

2. Capture Evidence

Record steps, tools used, results, and screenshots or logs where helpful. This ensures transparency and reproducibility.

3. Map to Business Impact

Frame the issue in terms of what it means for the organization. Translate technical risk into practical consequences.  Refer back to CTEM Phases 1 and 3 for context.

4. Store and Share Smartly

Feed findings into your risk register or reporting tools. Make sure the right people see the right results at the right time.

Conclusion: Validation Brings Clarity

You’ve scoped the problem, discovered your assets, identified potential threats, and prioritized what matters most. However, it’s only through validation that your assumptions become objective.

This phase is what gives your CTEM process teeth. It takes your prioritized exposures out of the abstract and into the real world, confirming whether they’re genuinely exploitable, or just noise.

That’s the kind of clarity that leads to better decisions, stronger defenses, and smarter use of your team’s time.

What’s Next: Phase 5, Mobilization

Now that you’ve validated which exposures are real, it’s time to act on them. In Episode 6, we’ll cover Mobilization, how to take what you’ve learned and turn it into measurable, strategic security improvements.

You’ll learn how to align fixes with risk, communicate outcomes across teams, and keep the CTEM engine running without stalling progress.

See you in the next phase.

What is EPSS?

The Exploit Prediction Scoring System (EPSS) is a data-driven risk model maintained by FIRST that predicts the likelihood of vulnerability being exploited in the wild within the next 30 days. It complements CVSS by focusing on real-world exploitability.
For example, a CVSS 9.8 vulnerability with an EPSS of 0.1% may pose less immediate risk than a CVSS 7.5 vulnerability with a 75% EPSS.
EPSS updates daily and is publicly accessible at https://www.first.org/epss/.

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