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What is defense in depth?

One of the primary goals for any organization should be to keep its resources secure. One way to do this is by preventing a threat from entering into the network. However, a more comprehensive approach to security is to set up multiple lines of defense to ensure that the threat doesn't get further access and expand the threat actor's foothold in the network. That is defense in depth.

This multi-layered approach to cybersecurity stems from a military principle focused on delaying the advance of an attacker rather than preventing their attack with a single line of defense. In cybersecurity, the principle is adopted with the knowledge that vulnerabilities can exist anywhere, so layering your security would give you the best defense against threat actors.

Defense in depth examples

Think of it in terms of soccer/football. The ultimate aim, of course, is to maneuver the ball away from your side of the court and into the opponent team's net. However, it isn't that simple as the opposing team possesses quite a few skills and has just as many tricks up their sleeve. A more comprehensive strategy is to set up players strategically to prevent the ball from getting through at the early stages; and should it pass that layer, have defensive players set up to steer the ball away from the goal.

Another way of looking at it is through the following puzzle. If the puzzle was carved with only a single layer of defense on the outside with a straight line to the middle, the path for the ball (i.e. the threat actor) to reach its target becomes very simple. However, when multiple layers are added in the middle, it makes it that much tougher for the threat actor to intrude.

Flow chart

However, when multiple layers are added in the middle, it makes it that much tougher for the threat actor to intrude.

Flow chart

The layers of defense in depth

Your network isn't just a single pane–it has multiple layers that work in unison with each other. If one layer is affected, the others are left vulnerable too. The following are the three main layers when looking at your defense in depth strategy:

  • Physical security:
    This involves protecting your physical assets such as devices and servers. You can implement controls such as physical access restrictions using keycards, and should employ security guards and cameras to protect your assets from insider threats.
  • Technical security:
    This covers protecting your hardware and software—including firewalls, intrusion detection or prevention systems, SIEM solutions, data loss prevention (DLP) software, etc.—from external threats.
  • Administrative security:
    These are the controls set by your organization's security team to secure company resources and sensitive data. This includes the policies implemented to prevent unauthorized access such as the principle of least privilege, as well as security awareness training.

Elements of a defense in depth strategy

Each organization's defense in depth strategy differs based on their architecture. However, there are a few defenses that are commonly adopted to layer an organization's security. Some of the defense in depth layers include:

1. Access control

  • Purpose:
    To ensure that only authorized users can access certain data or systems.
  • Implementation:
    This involves user authentication (such as passwords, and biometrics), authorization (defining what an authenticated user can do), and accounting (tracking user activities).
  • Defense in depth strategies:
    1. Multi-factor authentication (MFA) to mitigate unauthorized access.
    2. Implement the principle of Zero Trust to restrict system access to authorized users.
    3. Regular audits of user activities and permissions.

2. Perimeter defense

  • Purpose:
    To protect the network's boundaries from external threats.
  • Implementation:
    This is typically the first line of defense and includes hardware and software solutions.
  • Defense in depth strategies:
    1. Firewalls to monitor and control incoming and outgoing network traffic.
    2. Intrusion detection systems (IDS) and intrusion prevention systems (IPS) to identify and stop attacks.
    3. Virtual private networks (VPNs) to secure remote connections.

3. Network defense

  • Purpose:
    To safeguard internal network infrastructure and endpoint devices.
  • Implementation:
    This involves securing both the network and the devices that connect to it.
  • Defense in depth strategies:
    1. Antivirus and anti-malware solutions for detecting and removing malicious software.
    2. Network segmentation to isolate sensitive areas of the network.
    3. Regular software updates and patch management.
    4. Threat intelligence to guard the network against malicious intruders.
    5. Network monitoring solutions to detect any suspicious activity within the network.
    6. User and entity behavioral analytics (UEBA) to identify anomalous behavior that could potentially be a threat.

4. Applications security

  • Purpose:
    To ensure applications are secure from threats.
  • Implementation:
    This involves securing all software used by the organization.
  • Defense in depth strategies:
    1. Secure coding practices to prevent vulnerabilities.
    2. Regular application security testing (like penetration testing, code reviews).
    3. Web application firewalls (WAF) for protecting web applications.
    4. Application log collection and analysis to ensure the security and integrity of applications and data.

5. Data security

  • Purpose:
    To protect data integrity, confidentiality, and availability.
  • Implementation:
    This is about securing the data itself, regardless of where it resides.
  • Defense in depth strategies:
    1. Encryption of data to ensure sensitive data stays private.
    2. Data loss prevention (DLP) technologies to identify data vulnerabilities and prevent unauthorized data transfer.
    3. File integrity monitoring to track changes made to important resources.

The benefit of adopting a defense in depth cybersecurity strategy

The main benefit of adopting a defense in depth strategy is that it works on the principle that vulnerabilities will exist in an organization's architecture. In addition to helping fix the vulnerabilities, it also offers a fail-safe in case the vulnerability is exploited. This approach gives your security team more time to detect and respond to an attack and minimize its severity.

How a SIEM solution can enhance your defense in depth strategy

Adopting a defense in depth cybersecurity strategy can go a long way in delaying an attack and ensuring that your organization is protected, but implementing different solutions for each layer of the strategy and monitoring each element individually can be tedious and expensive. ManageEngine Log360 offers you the various capabilities required to enhance your defense in depth security. Here's how Log360 can help:

  • Real-time security analytics:
    Get complete visibility into network traffic, application security, and data security using Log360's real-time security analytics. All the events that take place in the network are monitored, analyzed, and presented in an interactive dashboard for quick analysis and response.
  • Threat intelligence:
    Get alerted of any external presence in your network by aggregating log data from IDS and IPS devices, firewalls, and your Active Directory infrastructure. Using Log360, you can leverage threat intelligence feeds to detect any known malicious sources to prevent an attack at the earliest stages. The solution's threat detection and response engine, VigilIQ, uses machine learning for precise threat detection, by establishing a baseline of regular activity to find anomalies.
  • UEBA:
    Identify the presence of external threat actors and reduce their dwelling time in your network by using UEBA. This capability establishes a baseline of normal user behavior to instantly detect any anomalies within the network.
  • Integrated DLP capabilities:
    Monitor, track, and prevent any unauthorized changes made to resources in critical files and folders using Log360's FIM module. Furthermore, you can classify files based on their sensitivity to decide how to prioritize the security level accordingly.
  • Automated incident response:
    Use Log360's automated incident response to enhance your attack remediation with real-time alerts and automated incident workflows; this is in case a threat actor manages to get past the various layers of defense.

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