August 25, 2023


An Introduction to Continuous Security Testing

Continuous security testing (CST) is the ongoing process of validating your defenses to know if they protect against emerging threats. The process aims to identify vulnerabilities, assess the effectiveness of security controls, and ensure ongoing security compliance. 

Unlike traditional security testing, which is conducted at fixed intervals, continuous security testing integrates assessments into the organization's development and operational processes. It involves automated techniques that are performed at frequent intervals throughout the operational life of systems.

Think of CST like a utility company: it is “always on”, without disruption. New piece of malware wreaking havoc in your industry? See if your CST solution is already testing it in your environment. Curious if the latest CVE is relevant to you? Log into your dashboard and check.

You pay for electricity but probably aren’t in the habit of checking your kilowatt usage every day. CST is the cybersecurity equivalent: it’s essential to do, but not necessary to monitor.

What makes continuous security testing unique?

No matter the strategy, security testing has always been point-in-time. When you run a security assessment, you plan, execute and report on the results. All of these are very timeline-centric: there is a distinct start and end to each phase of this process.

The problem is that technology moves too fast.

An Endpoint Detection & Response (EDR) tool, and the operating system it’s installed on, is under constant iteration. The programs are being updated. Features are being added. The pace of software development is that of a sprint, not a marathon. Each change brings the risk of a new vulnerability or a blind spot in the defensive agent, which hasn’t created a signature for a new malicious sequence of behaviors.

CST is a brand new approach. It takes the best of what came before, while improving upon many of the deficiencies. And it takes a radically different perspective. Instead of testing what the adversary can do, CST tests what the defense can protect against.

Continuous testing is designed to add interoperability with any defensive product that wants to harden its capabilities. It does this through a self-healing process, where every failure is reported to the defense, for automated or manual inspection and quick remediation.

These are many of the considerations we had when building Prelude Detect, our production-scale continuous security testing solution.

Why should you do continuous security testing?

Consider two questions:

  1. If every endpoint in your environment has zero vulnerabilities, are you safe?
  2. If every endpoint in your environment prevents all malicious behaviors - including insider threats and exploit attempts - are you safe?

Which is correct? The second one, of course.

Let’s make it more extreme. Let’s say every endpoint in your environment has every known vulnerability - but it still prevents all exploit attempts and blocks all malicious behaviors. Are you still safe? The answer is, amazingly, still yes.

What does this tell you? Endpoints are the center of your infrastructure. If you can protect every individual one, you have achieved a level of security in the 100th percentile. This should be more appealing than attempting to reach the unsatisfiable “good” state of patching vulnerabilities across your environment.

Continuous testing repeatedly - and consistently - validates your endpoint security is working.

How does continuous security testing differ from other security strategies?

Continuous Security Testing vs Vulnerability Management

Vulnerability management is a proactive approach to scanning, prioritizing and mitigating security vulnerabilities in an organization's IT infrastructure. The process starts by identifying Common Vulnerabilities and Exposures (CVE) across an environment. Each discovered CVE is prioritized, based on its potential impact, and scheduled to be patched, generally requiring the underlying software to be upgraded to a version without the security bug.

CST requires no scanning and no patching. Instead of learning what you are potentially vulnerable to, continuous testing exploits each endpoint and monitors how well the defense responds to each attack. If it is capable of preventing an exploit, the associated CVE should be treated as a lower priority to resolve.  

Continuous Security Testing vs Red Teams

Red teaming is a manual cybersecurity practice that involves simulating realistic attacks on an organization's systems, processes, or personnel to assess its overall security posture. The purpose of red teaming is to evaluate an organization's defensive capabilities by adopting the perspective of an adversary and identifying vulnerabilities that may not be apparent through perimeter-based security assessments.

The manual nature of red teaming creates a limitation on the scale of what can be tested. Often, red teams validate between one and 20 endpoints, extrapolating the security posture to the rest of the organization. CST is designed to run on all endpoints - simultaneously. 

Continuous Security Testing vs Breach and Attack Simulation

Breach and Attack Simulation, also known as BAS, is a cybersecurity practice that involves automating realistic attack scenarios to assess an organization's security posture and identify vulnerabilities. It focuses on testing the effectiveness of security controls, detection mechanisms, and incident response procedures in the event of a breach or cyber attack.

Instead of focusing on what an adversary can do, CST takes the perspective of your defense and determines how well you are protected. Each test evokes a response from your endpoint and determines - not only how it responds - but how to remediate the problem.

Continuous Security Testing vs Automated Penetration Testing

Penetration testing, also known as pentesting, is a cybersecurity practice that involves assessing the security of computer systems and networks by prodding them from the perimeter and finding initial points of access. The goal of pentesting is to identify weaknesses in the target system's infrastructure and provide recommendations for strengthening its security.

CST takes the stance that testing should revolve around “the endpoint” instead of the perimeter. An endpoint could be a laptop, workstation, server, container, virtual machine, traffic light, camera, WiFi-enabled toothbrush... basically, if the device is networked and runs code - it’s an endpoint. If each endpoint is protected, the devices behind it will be as well - even if the perimeter is breached.

Who cares about continuous security testing?

IT & Security Operations

Teams in charge of rolling out devices and managing their software care that they are safe. If endpoint defenses don’t work as expected, a security incident will cause significant work for this team, often making them scramble to remediate any lapses in protection.

Detection Engineering

Continuous testing allows detection engineers to validate that their detection rules are always working. Due to the variable nature of the tests, detection rules - such as Sigma-based rules - are stress tested against a constantly changing set of tests.

Offensive Security

Red and purple teams, charged with understanding the security posture of an organization, are able to feed new tests into CST. Because these teams understand what makes their organization unique, they can craft custom tests to validate scenarios of particular importance. Continuous testing elevates the importance of an offensive team because it boldly encourages testing on all production machines at all times.

Security Leadership

CISO’s, and other leaders in charge of purchasing security products, care that they work as expected. Common endpoint defenses, such as EDR agents, comprise a large part of the budget and bear a lot of the responsibility for protecting the fleet. Knowing that these agents can prevent cyber attacks - while not impeding business functions - is critical intelligence.

Executives and Board of Directors

Executives and the Board of Directors care that their organization is appropriately leveraged against risk. Without continuous testing, executives are forced to accept the promises of each vendor they purchase from, forcing them to overbuy and treat buying security as if it was an insurance premium. CST allows executives to have confidence in their security purchases and understand where they are vulnerable.

Learn more about continuous security testing

An Argument for Continuous Security Testing

This article provides a high-level overview of CST that should help you understand its importance and relevance. Truthfully, we've barely scratched the surface. Check out our form-free white paper, An Argument for Continuous Security Testing, for another 25 pages about forming the foundation of your security validation program with CST.

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Prelude Detect is a first-of-its kind continuous security testing product. Detect is an enterprise-capable SaaS offering that can be used by organizations with or without internal security teams. Detect leverages lightweight endpoint probes, one kilobyte a piece, which run alongside the endpoint defense. Every day, each probe runs a series of tests, often mimicking emerging threats from government intelligence, such as the CISA alerts and advisories feeds.

Ready to get started? Try Prelude Detect for free on up to 25 production endpoints.

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