4 Reasons Why Dynamic Security Testing Is Critical For All Your Assets

I’ve lost count of how many times this conversation has come up, usually in a conference room, sometimes on a Zoom call, almost always with good intentions. There’s a sentence I hear in almost every security strategy discussion:

“We’ll focus DAST on our Tier-1 apps. That’s where the real risk is.”

It usually comes with a spreadsheet, a neat classification model, and a sense of relief because narrowing the scope feels like control, but from an attacker’s perspective, that decision is a gift.

Restricting Dynamic Application Security Testing (DAST) to “critical” applications isn’t a mature risk-based approach. It’s a relic of how we used to build software, and it collapses completely under modern architectures, modern attackers, and modern DevSecOps tooling.

Let’s talk about why.

1. Attackers don’t target value — They target weakness

Security teams rank applications by business impact. Attackers rank them by resistance. That difference matters.

Your Tier-1 applications are usually:

• Protected by WAFs

• Closely monitored

• Regularly tested

• Owned by experienced teams

Your Tier-3 apps:

• Built fast, often once

• Rarely revisited

• Running old frameworks

• “Internal” until they aren’t

Attackers know this. They are not trying to breach your payment gateway directly; they are trying to gain access to your environment. Let’s be honest, automated, dynamic attacks are no longer the exclusive weapon of elite threat actors. They’re already being used daily by advertisers, growth teams, and product engineers to continuously probe user behavior, optimize flows, and exploit edge cases at scale. If entire industries are comfortable running relentless, automated experiments against their own systems, there is no defensible reason for CISOs and security teams not to do the same for security.

This blind spot is an AI-powered API-first world. Many modern applications expose a single /chat or agent endpoint and treat it as “just another API.” In reality, that endpoint often acts as a privileged control plane deciding what tools to call, which data to access, and which actions to execute. When authorization is loosely defined or implicitly trusted, these agents become perfect vehicles for privilege escalation, scope creep, and silent policy bypass.

Also, if you are not actively attacking your AI and agent endpoints with the same automation, creativity, and persistence that the business world already applies to growth experiments, you are not “managing risk” you are outsourcing discovery to the attacker.

DAST consistently shows that lower-visibility apps are where Auth assumptions break, Input validation is missing, Admin paths are exposed, and APIs trust network location over identity.

Once compromised, these apps become pivot points into identity systems, shared databases, internal APIs, or CI/CD infrastructure. This is not theoretical. This is how modern intrusions unfold. If an application can talk to anything meaningful, it is not “non-critical.” It is part of your attack surface.

2. “We know our apps” is usually an overstatement

Most organizations dramatically overestimate how well they understand their live application footprint.

In practice, environments contain:

• Old staging systems that were never torn down

• Legacy APIs supporting a single customer

• Marketing microsites deployed by third parties

• Temporary tools that quietly became permanent

These apps don’t show up in architecture diagrams. They show up when attackers find them.

One of the most practical values of running DAST broadly is forced asset discovery. You stop arguing about what should exist and start validating what does exist. From a security engineering perspective, this is foundational:

• You can’t prioritize what you haven’t enumerated

• You can’t monitor what you don’t know is reachable

• You can’t defend an attack surface you haven’t mapped

Broad DAST coverage turns unknown exposure into known risk, which is the first step toward reducing it.

3. Limiting DAST actively weakens security culture

This part is uncomfortable, but important. When you scan only a subset of applications, you’re sending a signal, intentionally or not, that security is optional depending on perceived importance.

What happens next:

• Internal tool teams never see real vulnerability findings

• Developers don’t build intuition for exploitable flaws

• Security feedback becomes centralized and elitist

Then, inevitably, a “non-critical” app becomes business-critical:

• A customer-facing extension

• A partner integration

• A revenue-adjacent feature

Now you’re shipping something externally that hasn’t seen years of runtime security validation. DAST isn’t just a control; it’s a teaching mechanism. It shows developers how their code behaves when attacked, not how it looks in a pull request. If you want secure-by-default engineering, security feedback has to be universal, not selective.

4. Old DAST excuses don’t hold anymore

Let’s address the elephant in the room. Legacy DAST tools were painful, with slow scans, fragile configs, endless false positives, and zero CI/CD friendliness. That’s where the fear of “scanning everything” comes from.

But modern DAST has fundamentally changed:

• Low false-positive rates drastically reduce noise

• API-first testing matches how apps are actually built

• Auth handling is no longer an afterthought

• Internal scanning can be done safely, without exposure

• Faster and incremental, CI/CD pipeline-friendly scanning

The trade-off between speed and coverage is no longer real. It’s a leftover assumption from tools that weren’t designed for modern delivery pipelines. Today, limiting DAST scope isn’t a technical necessity; it's a strategic choice. And usually, not a good one.

Risk no longer lives only where the business value is highest. It lives where assumptions break, and assumptions break most often in the places nobody is watching.

If an application is reachable, authenticated, or trusted by something important, it deserves DAST.

Instead of asking:

“Is this app critical to the business?”

Ask instead:

“What could an attacker reach from here?”

Modern attackers don’t breach the crown jewels directly. They enter through side doors, forgotten doors, and doors you didn’t know existed. Your security strategy should reflect that reality. This is exactly where modern application security platforms matter — not as point solutions, but as enablers of scale.

Platforms like Snyk are built on the assumption that risk no longer lives in one place. With Snyk API & Web (DAST), teams can continuously test both web apps and APIs, discover what’s actually exposed, and surface real, exploitable issues with evidence without slowing delivery. When combined with Snyk’s broader AppSec capabilities across SAST, SCA, containers, and infrastructure as code, DAST stops being a once-in-a-while audit and becomes part of how software is built and operated. The goal isn’t to scan more for the sake of it. It’s to remove blind spots, especially the ones hiding in the apps nobody thought were important.

Curious about the need for combining AI-driven SAST and DAST? Download The Gorilla Guide® To Unified SAST and DAST in the AI Era today.