How Dynamic Defense shuts an attacker out without shutting down the business

AI has handed hackers a resource advantage.

Winning it back means spending your own resources far more precisely, and that’s the strategy we call Dynamic Defense.

The principle is simple.

Contain the threat just enough, for just long enough, until the risk is removed. This piece shows how that works as a five-stage loop that keeps hackers out without shutting down the business.

And the need is clear enough.

Attacks that once took rare skill now just take AI, which has expanded their speed, scale and complexity and made hackers far harder to spot.

Most security tools still run on the old model of fixed policies, disconnected tools, delayed patching and slow response.

To stay ahead, that has to change.

How security teams can stay on the front foot against AI threats

It comes down to resources. AI has shifted the balance firmly toward attackers, letting them attack faster and at greater scale while our own resources have stayed the same. Any answer has to start there.

I go deeper on that shift in the first article in this series, worth reading if you want the full picture of how attackers are using AI and what it does to your resourcing: Static security has run out of road. The case for Dynamic Defense

Here, I want to focus on what to do about it.

To adapt, we need to be far more targeted about the resources we use to identify and stop attackers. Done right, that shifts the balance back in our favor.

This is the strategy we’re calling Dynamic Defense.

The fundamental principle is straightforward. Contain the threat just enough, for just long enough, until the risk is removed.

What Dynamic Defense is, and what it isn’t

It helps to be clear about what Dynamic Defense is, and what it definitely isn’t.

First, it’s certainly not about blocking everything. If that were feasible, we’d have done it already. It isn’t sprinkling “AI magic” over the same basic feature set, and it isn’t yet another dashboard for your team to watch.

Instead, Dynamic Defense rests on a few fundamental principles:

• Proportional response: Using only the minimum defense needed to stop the attacker.
• Cross-platform orchestration: Taking in the full context of an attack, so you can see what’s happening straight away.
• Adaptive containment: Understanding normal and anomalous behavior in forensic detail, so you can choose the right defense quickly.
• Faster remediation: Finding the fastest route to stop the threat and get back to normal operations.
• Business continuity: Keeping the impact of your defense on everyday work as close to zero as possible.

None of these objectives is new.

Security tools already use behavioral analysis to flag anomalies and pick a response. The problem is that most are far too blunt to deliver the forensic response I’m talking about here.

Here’s a clear example.

Today’s tools might spot a user logging in from a new location and flag it as a potential risk.

What they struggle to do is reliably tell the difference between attackers and ordinary employees logging in on vacation. That’s because most tools only see one thing at a time.

An endpoint detection and response (EDR) product sees the device’s location. An identity and access management (IAM) tool watches the user account’s location. A network tool spots anomalous traffic.

Each holds a single piece.

To really understand a threat, one tool needs all of those at once.

With that, it can see whether the user’s laptop and mobile are in the same place as the new login.

If they are, we can say with real confidence the login belongs to the employee.

If the laptop is abroad while the mobile sits in its usual place, the laptop is probably stolen.

If every device is where it should be and the login still comes from abroad, that’s almost certainly a remote attacker.

At its core, that’s the difference between a static and a dynamic response. Seeing this in granular detail lets us diagnose the problem, and the right response, far faster.

Step by step, how Dynamic Defense keeps out the hackers

Dynamic Defense has to run as a closed operational loop of five stages.

The aim is to contain the immediate threat now, then reinforce it with a more durable response in due course.

1. Detect changing risk

The first step is to spot when anomalous behavior is happening, and get a fast, forensic read on what the attacker is doing.

That means combining behavioral monitoring with signals from right across the IT environment:

• Users
• Devices
• Identity
• Email
• DNS
• Applications
• Vulnerabilities
• Remote access
• Threat-hunting activity

Say an attacker is using a vulnerability in Microsoft Word to infiltrate a device over the internet. That stands out fast, because Word rarely talks to the internet outside a couple of specific cases, Microsoft 365 Copilot and OneDrive.

Spotting it means correlating signals that network and device monitoring would normally pick up separately.

2. Reason and prioritize

Next, we weigh the full scope of the activity to work out what the attacker is really doing.

To do this, we combine AI-assisted correlation and risk-scoring with our existing playbooks, SOC workflows, and human approval.

The system then cross-references that anomalous network behavior to build a detailed profile of the activity. That can include:

• The anomalous network activity that generated the alert
• Device-level telemetry showing unexpected traffic to Microsoft Word
• The anomalous IP address checked against databases of known threat actors
• Any known vulnerabilities associated with these ports in Microsoft Word
• Whether the external connection is coming from a high-risk or unexpected origin for this user

That gives us a risk score we can trust, and lets us pin the threat down to the internet-facing ports (80 and 443) in Word.

3. Apply proportional control

Now we apply defenses to stop the attacker’s activity as fast as possible.

There’s a range of controls to draw on:

• Restrict privilege
• Control application execution
• Block malicious domains
• Isolate affected devices
• Remove malicious emails
• Restrict risky access
• Firewall blocking
• Update policies
• Patch exposed assets

The rule holds throughout. Apply the lightest control that closes the risk. With everything we’ve gathered, we can pick a highly targeted response.

Rather than isolating the whole device or taking Word offline, the system applies a dynamic process-level firewall rule that blocks winword.exe on ports 80 and 443, cutting Word’s internet traffic and nothing else.

We might also raise monitoring on the device or account to catch any other vectors.

The user keeps working, and other applications carry on untouched. That’s a proportional response to a confirmed risk, not a blunt instrument.

4. Remediate and restore

The firewall block is an elegant short-term measure, but it’s not a permanent fix. If a patch is already available, we install it quickly. If not, we wait for the vendor.

Once the patch for the Word vulnerability is deployed and verified, the system confirms the exposure is closed.

At that point we can take down the guardrails from the previous stage and return the device to normal operation. We also remove any malicious artifacts and residual risky access, validate the clean state, and document the incident.

5. Learn and adapt

Now the incident becomes training data for the system and the team using it.

Using the specific combination of signals we identified in the first two stages, we can codify the attack into a defined playbook, and use the same information to fine-tune policies, improve response thresholds, and update risk models.

All of this creates a feedback loop of richer context and sharper response. The more the system learns, the better it gets at catching the most complex and persistent threats.

Where Heimdal comes in

Everything above depends on cross-platform visibility, and that’s the part most vendors can’t reliably offer. It’s the precondition for the whole approach, and it’s also the hardest piece to build.

At Heimdal, this platform-wide approach has been the cornerstone of our strategy for several years.

Today our platform spans the full range of security products, including network security, vulnerability management, endpoint detection, email security, DNS, and malware detection, which is exactly the basis this approach needs.

We’re now building Dynamic Defense into the platform itself, and rolling it out in stages over the coming months and quarters.

That work is firmly underway rather than finished, and I’d rather be straight about that than overstate it.

First and foremost is the Threat-hunting and Action Center (TAC), our fully integrated SIEM and XDR product, which correlates real-time behavioral signals across networks, endpoints, cloud environments, email, and identity.

It’s the engine that gives you visibility over everything happening in your IT environment.

We can go further by combining it with AI Wingman, our new suite of AI security tools:

AI Wingman Assist: The performance layer helps everyday users get more out of Heimdal, by applying best-practice settings, reaching value faster after setup, and making sense of what your alerts are telling you.

AI Wingman Triage: The investigative support layer analyzes data from the Threat-hunting and Action Center to work out what the attacker is up to. Powered by Heimdal’s multi-agent engine, it helps teams assess suspicious signals faster and identify the right response.

AI Wingman SOC: By combining AI with Heimdal’s security operations center, we upgrade our managed service response, giving our analysts a faster route to identifying attacks, prioritizing the right response, and reducing business disruption.

AI Wingman is now rolling out, and will be added to the Heimdal platform through the rest of 2026.

This is the basis of the Dynamic Defense I’ve described here. To find out more, take a look at our recent guide or get in touch with our team.

Morten Kjaersgaard

Chairman and Founder

Morten Kjaersgaard is the Founder and Chairman of Heimdal®, a global leader in AI-powered cybersecurity. Under his leadership, Heimdal has grown from a startup in Copenhagen to a trusted security partner for over 16,000 organizations and more than 2,000 MSPs worldwide, defending against 260+ million cyber threats annually. With a sharp focus on unifying cybersecurity operations, Morten is recognized for his ability to align technical innovation with strategic business outcomes. His insights have shaped how organizations and partners alike approach risk reduction, compliance, and security maturity in an increasingly complex digital world. A respected voice in the industry, Morten frequently shares his expertise at international events and through media commentary—championing a more proactive, collaborative, and scalable model for cybersecurity success.