Layered Security – How a Defense-in-Depth Approach Guards Against Unknown Threats

Today’s rapidly-evolving cybersecurity landscape means businesses are under more pressure than ever. A sophisticated range of threats now aim to bypass traditional defenses, which leaves organizations vulnerable if they’re still relying on legacy tools like antimalware software.

These often aren’t able to spot advanced threats like zero day exploits that take advantage of unknown software flaws, fileless malware that evades detection by operating in memory, or social engineering tactics that trick users into granting access in order to breach firms’ perimeters.

Once inside networks, they can often then move undetected and exfiltrate sensitive data with alarming ease. To counter these threats, businesses need to adopt a layered security approach that can protect every point of attack, reducing risk and improving resilience.

Layered security, also known as defense in depth, is a cybersecurity strategy that uses multiple layers of protection to defend against threats at every stage of an attack. Instead of relying solely on perimeter-based defenses or signature-based detection, this approach integrates various controls and measures to create a resilient security posture.

Today’s sophisticated cybercriminals use advanced tactics like zero day vulnerabilities to exploit unknown software flaws or utilize legitimate tools to launch ransomware attacks. Indeed, our research indicates that in 2024, over half of ransomware attacks (56 percent) used PowerShell. These methods allow intruders to bypass traditional security solutions that depend on known signatures and perimeter-focused thinking.

A layered security model looks beyond traditional methods of detecting instructions. By analyzing and monitoring systems holistically, organizations can detect, block and respond to threats at multiple points, reducing the risk of data exfiltration and operational disruption.

A comprehensive defense in depth strategy should combine multiple controls and processes that work together to protect sensitive data at every stage of an attack. Each layer addresses a different part of the threat landscape, helping to prevent attackers from exploiting a single vulnerability to gain access. Below are six key aspects that every organization should consider when building a strong, layered security approach.

Network security forms the backbone of any layered defense strategy. It involves securing the flow of data across your network using technologies like firewalls, intrusion detection systems and network segmentation. Elements that must be considered as part of this include:

• Firewalls to help control incoming and outgoing traffic.
• Antimalware software to alert firms to known threats.
• Intrusion detection systems that monitor internally for suspicious behavior.
• Network segmentation to divide your network footprint into isolated segments, limiting an attacker’s ability to move laterally if they gain access.
• Zero trust network access to ensure remote connections are verified every time they attempt to access sensitive data.

Physical security is often overlooked but is a critical line of defense. It focuses on protecting the physical infrastructure, including offices, data centers and hardware, from unauthorized access and tampering. Without proper physical protections, attackers can gain direct access to devices or network equipment, bypassing even the most robust digital defenses.

As well as protecting facilities like servers, this includes steps to guard against lost and stolen laptops or company smartphones, such as the ability to wipe compromised devices remotely.

Endpoint protection is crucial because devices are often the first point of contact for cybercriminals. This layer ensures that all equipment is secured against threats like malware and ransomware and can both block unauthorized access and prevent data from being exfiltrated.

Modern endpoint protection solutions are essential as the number of devices grows. As well as assets like desktops, laptops and servers, solutions must take into account IoT sensors, printers and employee-owned mobiles. Since employees often work remotely or from multiple locations, ensuring endpoint protection across all devices helps close gaps that attackers might otherwise exploit when users are outside traditional network perimeters.

Application security focuses on protecting the software applications that your business relies on, including web apps and internal tools. Among the common threats these efforts aim to mitigate are:

• Insecure APIs
• Misconfigured settings
• Injection attacks
• Outdated software
• Weak encryption

Secure development practices, such as regular code reviews, vulnerability testing and patch management, help identify and fix these issues before they can be exploited.

Data security focuses on keeping your most valuable information safe. This layer involves protecting data both at rest and in transit using encryption and access controls to ensure there can be no unauthorized access, modification, copying or deletion of data. Aspects that fall into this area of layered security include:

• Data classification to determine which information is most sensitive and requires the highest levels of protection.
• Regular data backups that ensure critical information can be restored quickly in case of an attack, minimizing downtime and data loss.
• Access controls such as multifactor authentication and zero trust data protection principles to verify the identity of any account attempting to view data.
• Anti data exfiltration solutions to automatically block any unauthorized attempts to remove data from the network.

Finally, the human element must not be overlooked. Employees are often the weakest link in any security strategy, with some estimates suggesting as many as 95 percent of data breaches involve some form of human error.

Cybercriminals frequently exploit human errors through social engineering tactics like phishing and credential theft, making education a critical layer of defense. Regular training on cybersecurity best practices, recognizing suspicious activity and reporting incidents can significantly reduce the risk of successful attacks. User education should also include awareness of policies and procedures, such as using strong passwords and avoiding risky online behavior.

A layered security approach provides comprehensive protection for businesses facing an ever-evolving threat landscape. By combining multiple security measures, from physical security to user education, organizations create a resilient defense that protects data at every point.

This defense-in-depth strategy ensures that even if one layer is breached, others are in place to detect, contain and respond to threats like zero day exploits and ransomware attacks. This allows businesses to significantly reduce the risk of data exfiltration, protect sensitive information and maintain operational continuity in the face of modern cyberthreats.