What is Defense in Depth? Defined, Explained, Know More in 2021

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What is Defense in Depth? Defined and Explained

Defense in Depth refers to an information security approach to ensure the confidentiality, integrity, and availability of the network and the information within a computer network and carefully place a range of security mechanisms and controls. Although no one can stop any cyber threats, together, they mitigate a wide range of threats and incorporate redundancy if one tool fails. This approach dramatically improves network safety against numerous attack vectors when it is successful. These (and other) best practices, instruments, and policies can be included in an effective DID strategy.

How Defense in Depth Work?

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All IT systems levels can be covered in a layered approach to security. Defense in Depth can significantly improve your security profile from the single laptop accessing the internet from the coffee shop to the 50 thousand WAN users.

No single security layer can ever fully protect an organization. If one door is closed, others are left open, and hackers will quickly detect those vulnerabilities. However, you effectively close the gaps created with a unique security response by using various defenses together, such as firewalls, malware scanners, intrusion detection systems, data encryption, and complete audits.


Firewalls are software or hardware that control traffic by accessing or denying policies and rules. These rules cover IP addresses, MAC addresses, and ports that are blocked or blacklisted. There are also application-specific firewalls such as WAF and secure email gateways to detect malicious activity directed to a given application. There are also security email gateways.

Detection of intrusion

The IDS sends an alert to detect malicious traffic in the network (e.g., Albert Network Monitoring). At the same time, the IPS attempts to prevent and warn against the malicious activity identified on the web or the user's workstation. These solutions recognize attacks on signatures of malicious network activities. These solutions support the identification.


Software or agents reside on a customer system and provide antivirus protection, alert, detection, analysis, triage of threats, and intelligence capabilities, for example, on a user's laptop or mobile phone. These solutions work under rule sets or heuristics (e.g., signatures or firewall rules) (i.e., detecting abnormal or malicious behaviors).

Network Segmentation

It is the practice of dividing a network into multiple business networks. This often involves sub-networking for managers, finance, business, and human resources, for example. These networks may not be able to communicate directly, depending on the level of security required. Segmentation is often achieved with the use of a firewall or network switches.

Least Privilege Principle

Policy and technical controls must only grant access to resources (networks, systems, and files) for users, systems, and processes necessary for their functions to be performed.

Strong Passwords

In information security, strong passwords are a critical authentication mechanism. Modern password management includes multi-factor authentication, use a multi-word password phrase and not reuse passwords for any value account.

Patch Management

Patch Management is an operating system, software, hardware, or plugin update process. These patches often address vulnerabilities that might enable unauthorized CTAs access to IT systems or networks.

Elements of Defense in Depth

Security companies are continuously developing new safety devices to protect networks and systems with a growing landscape of security threats to address. Here are some of the most common security aspects of a strategy for defense in depth:

Network Security Controls

Network traffic analysis represents the first line of defense when securing a network. Firewalls prevent access and block traffic from unauthorized networks based on a set of rules of security. Intrusion protection systems often work together with a firewall to identify and respond rapidly to potential security threats.

Antivirus Software's

Antivirus software is critical for virus and malware protection. However, many variants often rely heavily on the identification of signatures. While these solutions offer strong protection against malicious software, savvy cyber criminals can use signature-based products. This is why an antivirus solution with heuristic characteristics to scan for suspicious motifs and activity is wise.

Data Integrity Analysis

Each system file has what it's called a checksum. This is a mathematical image of a file that shows how often its use and source are used to check for a known list of viruses and other malicious code. If an incoming file is fully system-unique, it can be labeled suspicious. The IP address source may also be monitored for data integrity solutions to ensure that it is from a known and trusted source.

Behavioral Analysis

File and network behaviors often provide insight during an infringement. The firewall or intrusion protection solutions have failed if behavioral analysis is on. The behavioral analysis collects slackness and can send warnings or execute automatic controls that prevent further breaches. To function effectively, companies need to lay down the foundations for "normal" behavior.

Why a Defense in Depth Approach Matters?

However, a DiD strategy ensures redundant network security, preventing a single fault point. There is no silver bullet in cyber security. DiD's process significantly increases the time and complexity necessary to effectively compromise a network that drains further resources from engaged cyber threat actors and increases the chance of an active attack before it is completed.

The DiD approach is routinely used to protect valuable equipment or other materials in the field of physical security. For instance, polling stations often have a custody chain, security cameras, and locks to protect electoral equipment and associated infrastructure in the physical polling environment. Safety cameras, ballistic glass, and vaults are used to protect assets and staff in the banking world.

What you should do?

It's the firewall, as mentioned above, that provides your first line of defense in the defense strategy of your company. It is therefore sensible to select a solution which offers a range of features to protect modern businesses' changing needs from the constantly evolving threat scene.

Happy Learning

Rohan Girdhani

Information Technology Consultant


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