How to Defend Against Advanced Persistent Threats

Every cyber threat is bad for business, but some are much, much worse.

While ransomware hits hard, making its presence known, the real danger comes from those hidden attacks that infiltrate quietly and dismantle your network from the inside. 

Commonly, they are known as Advanced Persistent Threats (APTs).

Unlike smash-and-grab attacks designed for quick financial gain, APTs are calculated, patient, and relentless. 

They:

• Use advanced, multi-stage attack techniques.
• Remain undetected for months or even years.
• Target high-value organisations.
• Have long-term objectives (often political, economic, or espionage-related)

Because APTs remain undetected for so long, their damage can be widespread and devastating. Businesses that fall victim risk data theft, intellectual property loss, operational disruption or even total business failure.

APTs are broad and exploit weaknesses across your entire security setup. Stopping them requires a multi-layered, proactive defence strategy. 

Here are the 4 key preventative measures every business needs to take: 

1. Threat detection
2. Strong access controls
3. Comprehensive testing
4. Incident response planning. 

Let’s start off with the basics:

Threat Detection

As APTs operate stealthily, the key is to spot them early before they cause major damage. 

To keep things simple, I’ll take you through the 5 main ways to identify these advanced threats:

1. AI-Powered Detection 

It’s time to replace your traditional antivirus tools.

Sure, they can stop old, well-documented attacks but these systems really struggle when it comes to new or modified malicious activity.

So, instead of relying on a machine with a predefined list of threats, use AI-driven security tools that study how users and systems typically behave. When something out of the ordinary happens, the system can actually flag this behaviour as suspicious and alert your security team.

For example:

• An employee suddenly downloads a large amount of data outside normal working hours.
• A user logs in from an unexpected location or rapidly switches between multiple IP addresses. 

Both cases could be signs of a hacked account. But AI threat detection can help you catch these risks early.  

2. Central Threat Management

Security Information and Event Management (SIEM) tools give you a clear, real-time view of your security landscape. 

Instead of sifting through endless logs and systems, they centralise all security data, helping teams spot threats faster and respond smarter.

SIEM tools can: 

• Detect long-term attack patterns that indicate APT activity.
• Merge data from firewalls, antivirus, and network activity for better visibility.
• Connect the dots between seemingly unrelated threats.
• And provide real-time alerts if something suspicious happens. 

3. Next-Generation Firewalls

A firewall is a basic cybersecurity tool that filters network traffic to block unauthorised access.

But attackers have found ways around them. 

They can: 

• Hide threats in encrypted traffic so they go undetected. 
• Disguise attacks as normal system activity to bypass firewall rules.

Next-generation firewalls add extra protection to stop these advanced threats, such as:

• Scanning network traffic in detail to spot hidden risks (Deep Packet Inspection – DPI).
• Automatically blocking known attacks before they cause harm (Intrusion Prevention System – IPS).
• Filtering harmful requests to protect specific apps from targeted attacks.

4. Endpoint Detection and Response (EDR)

Hackers often target endpoints, like employee laptops, phones, and cloud servers, to break into a network. 

Once inside, they move through the system, stealing data over time – a common tactic in APT attacks.

EDR solutions continuously monitor these devices, detecting and stopping threats before they spread. 

Warning signs of an attack include:

• Login attempts from unknown locations.
• Unusual file changes, like malware altering system files.
• Irregular data transfers, which may mean sensitive data is being stolen.

5. Deception Technologies 

Deception technologies trick attackers into engaging with fake systems, giving businesses insight into their tactics and tools.

These include:

1. Honeypots 

• Fake digital assets designed to attract hackers, letting security teams monitor their behaviour before they reach real systems.

2. Decoy user credentials

• Artificial login details can be strategically planted in phishing traps, luring attackers into a monitored, isolated environment.

Note: This strategy isn’t for everyone. 

It carries some risk and is best suited for well-established organisations with larger cybersecurity budgets.

Strong Access Controls

A great way to stop unauthorised access is by using zero-trust security.

This approach means no one and nothing, whether inside or outside your network, is automatically trusted.

Every user, device, and app must prove they’re safe before getting access, making it much harder for attackers to slip through.

Here’s how to enforce it:

• Multi-Factor Authentication (MFA): Require at least two forms of verification (e.g. password + text code) to access sensitive systems.
• Continuous Monitoring & Verification: Checking a user once isn’t enough. Real-time tracking ensures they stay verified and flags suspicious activity.
• Principle of Least Privilege (PoLP): Users should only have the access they need. For example, an HR employee can view payroll data but not edit it. Role-Based Access Control (RBAC) applies these limits.
• Network Segmentation: Dividing a network into sections stops attackers from moving freely. If one part is breached, they can’t access everything.

APT groups often use stolen credentials to sneak through networks.

But, with strict access controls in place, a hacker who breaches an HR employee’s account wouldn’t automatically gain access to financial records or confidential business data.

Comprehensive Testing

Regular security testing helps organisations find and fix vulnerabilities before real attackers exploit them.

Two of the best ways to test your defences are penetration testing and Red Team exercises – both simulate cyberattacks but with different goals.

Penetration Testing vs. Red Team Exercises

• Penetration Testing is a short-term assessment where ethical hackers look for known security gaps in your systems, apps, or network and report their findings.
• Red Team Exercises are deeper, long-term simulations that test not just your technology, but also how well your people and processes detect and respond to real-world threats.

A combination of both helps organisations stay ahead of APT threats by strengthening their technical and operational security.

At Cyber Alchemy, we offer both Penetration Testing Services and Red Team Simulations to help businesses improve their defences.

But remember, finding security gaps is just the first step, fixing them fast is what really keeps you safe.

Rapid Response Planning

APTs can remain undetected for long periods, causing large amounts of damage before they are ever discovered. 

That’s why having a solid Incident Response Plan (IRP) is crucial – it helps detect, contain, and eliminate threats before they get worse.

Here’s what makes a strong Incident Response Plan:

1. Defined Roles & Procedures. Make sure everyone knows what to do during an attack, from who takes charge to how incidents are escalated.
2. Secure Backups. Make sure regular, encrypted backups are stored offline to enable quick recovery in case of data compromise.
3. A Communication Plan. Prepare clear, pre-written messages for customers, regulators, and stakeholders to manage the fallout of a breach.
4. Review & Improve Sections. After an attack, plan to analyse what happened, identify weak spots, and strengthen your defences.

Note: Attackers may have multiple backdoors into a system, allowing them to regain access even after detection.

A strong, APT-focused response plan helps security teams act fast, lock down systems, and wipe out threats completely, so attackers can’t return.

Stay One Step Ahead of Advanced Persistent Threats

Now that you’ve gone through this guide, you should have a solid grasp on how to:

• Spot threats before they take hold
• Stop attackers from moving freely through your systems
• Test your defences the way real hackers would
• Respond quickly and shut down attacks for good

So, take a moment. How does your security stack up?

Would your business be ready to face an APT attack?

If you’re not sure, Cyber Alchemy has you covered. We offer expert security testing and tailored protection to keep your business safe.

Contact us now to start strengthening your defences.