Medical IT Support

What is Layered Security & How Does it Defend Your Network?

Layered Security

Doing business online has never been easier – or riskier. From ransomware and phishing to data breaches and insider threats, cyberattacks are more frequent, more sophisticated and more damaging than ever. For many organisations, a single successful attack can mean days of downtime, lost revenue, reputational damage and expensive recovery work.

Strong cybersecurity is no longer a “nice to have” – it’s a core business requirement. But there’s a problem: no single security tool or control can protect you from every threat.

That’s where layered security (also called “defence in depth”) comes in. Instead of relying on one line of defence, you build multiple protective layers across your people, processes, devices, data and networks. If one safeguard fails, another is there to catch the attack, slow it down or limit the damage.

In this guide, our cybersecurity specialists in Perth break down:

What Is Layered Security?

Layered security is a cybersecurity strategy where you implement multiple, overlapping security controls across your environment – from endpoints and networks to applications, data and staff training.

Instead of putting all your trust in a single “silver bullet” tool, you assume that any one control can be bypassed. So you build a stack of safeguards that work together to:

Think of it like security in a modern office building:

If someone manages to slip past the fence, they still have to get through multiple additional barriers before they can do serious damage. Layered security applies the same concept to your digital environment.

Why Layered Security Matters for Your Business

1. Cyberthreats are constantly evolving

Cybercriminals aren’t standing still. They’re:

Using AI and automation to send highly targeted phishing emails at scale
Exploiting new vulnerabilities in software and cloud services
Leveraging stolen credentials from past data breaches
Combining multiple techniques in a single attack (phishing + malware + extortion)

A one-dimensional security setup—like “we have an antivirus, we’re fine”—can’t keep up. A layered approach gives you redundancy and resilience as threats evolve.

2. Human error is unavoidable

Even the best-trained employee can:

Layered security assumes that mistakes will happen, and builds controls that minimise the impact when they do – for example, multi-factor authentication, restricted access and data loss prevention tools.

3. Compliance and client expectations

If you handle sensitive personal, financial or health information, you may be subject to regulatory requirements and industry standards. Even when formal regulations don’t apply, customers increasingly expect their data to be handled securely.

A layered security strategy helps demonstrate that you:

Core Principles of a Layered Security Strategy

Before diving into specific layers, it helps to understand the core principles that underpin a strong defence-in-depth approach:

1. Assume breach
Work as though an attacker will eventually get past one of your defences. Design your environment so that a breach is detectable, containable, and recoverable.

2. Least privilege
Users and systems should only have the minimum access they need to perform their roles. If an account is compromised, limited access equals limited damage.

3. Segmentation
Don’t treat your network like one big open room. Separate critical systems, sensitive data and user groups so attackers can’t move freely.

4. Redundancy
Don’t rely on a single control. If your firewall misses an attack, your endpoint protection, email filtering or user training might still catch it.

5. Visibility and monitoring
You can’t protect what you can’t see. Logging, monitoring and alerting are essential to spotting suspicious behaviour early.

6. Continuous improvement
Cybersecurity is not “set and forget”. Controls, policies and training need regular review and updates to stay effective.

The Key Layers of a Modern Security Stack

A practical layered security approach can be thought of as several interlocking layers. Let’s walk through the key ones and what you should be doing at each level.

1. Endpoint & System-Level Security

Endpoints are any devices that connect to your network: desktops, laptops, tablets, mobiles, servers and even some IoT devices. Attackers love endpoints because they’re everywhere and often used by non-technical staff.

Essential endpoint controls

MFA adds an extra layer by requiring something you have (like a phone or security token) in addition to something you know (your password). This dramatically reduces the risk from stolen or guessed passwords.

Modern endpoint protection goes beyond traditional signature-based antivirus. It uses behavioural analysis and machine learning to detect ransomware, fileless attacks and suspicious processes.

EDR tools continuously monitor endpoints for unusual activity, helping your IT team investigate and respond quickly to incidents.

Host-based firewalls on each device can filter incoming and outgoing traffic, creating an extra barrier even if your network firewall is compromised.

Keeping operating systems and software up to date is critical. Many successful attacks exploit known vulnerabilities that have already been patched – just not on your systems.

Full-disk encryption protects data on laptops and mobiles if they’re lost or stolen.

2. Network-Level Security

Network level security - Computing Australia Group

Your network is the backbone that connects your devices, servers and cloud services. Network-level security focuses on controlling who and what can move through that backbone.

Core network protections

Firewalls create a controlled “chokepoint” between your internal network and the internet. They:

These tools monitor network traffic for suspicious patterns and either alert your team (IDS) or automatically block threats (IPS).

Instead of one flat network, you create separate zones, such as:

If attackers compromise one segment (e.g., guest Wi-Fi), they can’t automatically access everything else.

Wi-Fi is a common weak point. Improve its security by:

NAC solutions identify and enforce policies on devices connecting to the network. For example, blocking unmanaged or non-compliant devices, or restricting them to a limited network segment.

Deploying anti-malware and content filtering at the network edge helps block malicious downloads, command-and-control traffic and known bad domains.

3. Application-Level Security

Your applications – email, web apps, CRM, ERP, file sharing tools and more – are often the front door for attackers. Application-level security focuses on protecting these entry points.

Email security (your biggest risk area)

Email remains the number one vector for phishing, malware and social engineering.

Key controls include:

Advanced spam and phishing filters
These scan for suspicious links, attachments, spoofed senders and known phishing patterns.
Attachment sandboxing
Potentially risky attachments are opened in a secure, isolated environment to see if they behave maliciously before they reach users.
Link (URL) scanning and rewriting
Links are checked and, if necessary, rewritten so clicks are routed through a secure scanner.
Impersonation protection
Helps detect emails pretending to be from executives, suppliers or well-known brands.

Web application and software security

For your websites, online portals and internal applications:

Secure development practices
Incorporate security from the design stage (e.g., input validation, secure authentication, proper error handling).
Regular code reviews and penetration testing
Identify and fix vulnerabilities like SQL injection, cross-site scripting (XSS) and insecure direct object preferences.
Web Application Firewalls (WAFs)
WAFs sit in front of web applications and filter malicious HTTP traffic.
Strong authentication and session management

Secure file transfer (FTP replaced and hardened)

Traditional FTP is insecure by default. You should:

4. Transmission-Level Security

Transmission-level security focuses on protecting data as it moves between systems, locations and users.

Encryption in transit

HTTPS / TLS for websites
and web apps Any site or portal where data is entered or viewed should use HTTPS. This protects against eavesdropping and tampering.
Secure email transmission
Transport Layer Security (TLS) between mail servers and end-to-end encryption for highly sensitive content.
Virtual Private Networks (VPNs)
VPNs create an encrypted tunnel over the internet for remote workers or branch offices. This:

Choose business-grade VPN solutions, enforce strong authentication and regularly review access rights.

5. Data-Level Security

At the end of the day, attackers are usually after your data. Protecting data directly is a critical layer that sits on top of system and network defences.

Key data protection practices

Data classification
Identify and categorise your data (e.g., public, internal, confidential, highly sensitive) so you can apply appropriate controls.
Encryption at rest
Encrypt sensitive data on servers, databases and backups. If a system is compromised or a device is stolen, encryption helps keep the data unreadable.
Access control and permissions
Apply “least privilege” at the data level. Only the people who genuinely need access to specific folders, systems or records should have it.
Data Loss Prevention (DLP)
DLP tools monitor and control the movement of sensitive data (for example, stopping staff from emailing client lists to personal accounts).
Backup and recovery
Regular, tested backups are a critical part of layered security. If ransomware strikes or data is accidentally deleted, backups allow you to restore:

6. Identity & Access Management (IAM)

Identity is the new perimeter. With cloud services, remote work and mobile access, controlling who can do what is a crucial security layer.

IAM essentials

Centralised identity management
Use a central directory (e.g., Active Directory, Azure AD) to manage user accounts, roles and access across systems.
Role-based access control (RBAC)
Assign permissions based on roles, not individuals. This simplifies management and reduces the chance of “access creep”.
Multi-Factor Authentication (MFA) everywhere possible
Apply MFA to:

7. The Human Layer: Training, Culture & Policies

Technology alone can’t secure your organisation. Your people are both your biggest risk and your strongest defence.

Security awareness training

Regular, practical training should cover:

Recognising phishing and social engineering
Safe handling of email attachments and links
Password hygiene and MFA
Secure use of remote access and public Wi-Fi
Reporting suspicious activity or potential incidents

Short, frequent sessions and real-world examples are more effective than long, one-off seminars.

Simulated phishing campaigns

Running controlled phishing simulations helps you:

Clear, accessible policies

Policies should be:

Key policies include:

8. Monitoring, Logging & Incident Response

Even with strong defences, you must be prepared for detection and response.

Centralised logging and monitoring

Collect logs from:

Use monitoring tools or a Security Information and Event Management (SIEM) platform to:

Incident response planning

A good layered security strategy includes a clear plan for when things go wrong:

Define roles and responsibilities during an incident
Document steps for containment, investigation and recovery
Establish communication plans for internal stakeholders and (if needed) clients or regulators
Run tabletop exercises to rehearse scenarios in a low-stress environment

As we always tell our clients, your staff are the first line of your defence. Providing your employees with proper and regular cybersecurity training can keep them updated about the threats out there. They will be aware of the necessary measures to take in case of a cyber breach. Trained employees can easily avoid falling into phishing attacks and other data leakage attacks.

A well-planned and executed layered security policy for your organisation protects it from most kinds of cyber-attacks. Secure your data, network, and business today. To get a well-rounded security system for your organisation, contact our cybersecurity experts at Perth or email us at cybersecurity@computingaustralia.group.

Jargon Buster

VPN (Virtual Private Network) – A secure, encrypted connection that allows users to access a private network over the internet, protecting data from interception.
Phishing – A form of fraud where attackers pose as trusted individuals or organisations (often via email or SMS) to trick you into revealing sensitive information or installing malware.
Endpoint – Any device that connects to a network, such as desktops, laptops, tablets, smartphones, or servers.
Ransomware – Malware that encrypts your files or systems and demands payment for the decryption key.
Multi-Factor Authentication (MFA) – An extra layer of security requiring two or more verification factors (e.g., password + SMS code or app approval).
EDR (Endpoint Detection & Response) – Security tools that continuously monitor devices for suspicious activity and support investigation and response.
Network Segmentation – Splitting a network into smaller, isolated sections to limit how far attackers can move if they gain access.

Blake Parry

FAQ

Is layered security only for large enterprises?

No. While the concept comes from large organisations and governments, small and medium businesses need layered security just as much, if not more. Smaller organisations are often targeted precisely because they’re perceived as easier to breach.

How many layers of security do I actually need?

There’s no magic number. What matters is that you have multiple, overlapping controls across:

1. Endpoints

2. Network

3. Applications

4. Data

5. Identity & access

6. People (training and policies)

Even a simple but well-thought-out stack is better than an impressive single tool used in isolation.

Isn’t a good firewall and antivirus enough?

Not anymore. Firewalls and antivirus are important—but attackers now use:

1. Social engineering

2. Stolen credentials

3. Cloud misconfigurations

4. Supply chain vulnerabilities

A layered approach recognises that any single control can fail, so you need backup defences.

How do I know if my existing security is “layered” enough?

Start with a security assessment or audit. This will:

1. Map your current controls

2. Identify gaps (e.g., no MFA, weak backups, flat network)

3. Prioritise improvements based on your risk profile and budget

From there, you can work with internal IT or a trusted partner to build a roadmap.

Can I implement layered security gradually?

Yes—and that’s often the most realistic approach. Many businesses roll out improvements in phases, for example:

1. Phase 1: MFA, backups, email security, patching

2. Phase 2: Network segmentation, advanced endpoint protection, VPN review

3. Phase 3: DLP, SIEM/monitoring, formal incident response planning

The key is to start and keep progressing.