Enterprise IT environments are larger and more complex than ever, from SaaS and cloud applications to remote access. According to a survey by Randori, 67 percent of organizations say that their Internet-connected assets have increased in the past two years (Randori, 2022).
The growth of enterprise IT has tremendously enhanced employee productivity and efficiency. However, it also presents new opportunities for hackers to find and exploit vulnerabilities. Thus, businesses must remain vigilant, taking steps to understand and protect themselves against potential attacks.
One tool that can help with cybersecurity threat modeling is an attack tree. You will learn all there is to know about attack trees in this post. We’ll go over the definition of an attack tree and why they’re so helpful for modeling cybersecurity threats.
What Is an Attack Tree Model?
In cybersecurity, an attack tree is a model of how a malicious actor might seek access to an IT asset, such as a system or network. Computer security professional Bruce Schneier was one of the first to develop and publicize the notion of attack trees.
Attack trees have the shape of a tree diagram:
- A single root node at the top represents the hacker’s ultimate goal.
- The children of the root represent different methods that can be used to achieve this objective.
- The children of these children represent subproblems that must be solved along the way.
What Is the Purpose of Attack Trees?
The purpose of an attack tree is to help identify the potential dangers to a system or network. Above all, attack trees outline malicious actors’ various techniques to achieve their goals. This helps organizations better understand the methodologies of their opponents and take steps to counter them.
For example, consider an attack tree whose root node represents the ultimate goal of opening a safe:
- The children of this node represent the various methods that could accomplish this goal. These include picking the lock, learning the safe’s combination, and cutting open the safe.
- Some of these children have their own children. For example, to learn the safe’s combination, an attacker could find the combination written somewhere or obtain it from someone who knows it.
- This second grandchild node (obtaining the combination) has its own great-grandchildren. For example, to get the combination from someone, the attacker could threaten, bribe, or eavesdrop on that person. Although this is a toy example, it shows how highly complex attack trees can be. Multiple levels and nodes of the tree represent different stages and methods of attack.
What Are the Advantages of Using Attack Trees?
Attack trees are an essential concept in the field of threat modeling in cybersecurity. Threat modeling involves finding, analyzing, prioritizing, and preventing threats to an IT environment, system, or network. By using threat modeling, businesses can conceptualize the risks they face and strengthen their cybersecurity posture.
Of course, attack trees are just one example of how security professionals can perform threat modeling. Other examples include the STRIDE model developed at Microsoft (Microsoft, 2022).
The STRIDE model splits cyberthreats into six groups. These categories are spoofing, tampering, repudiation, information disclosure, denial of service, and elevation of privilege. Threat modeling techniques such as attack trees and the STRIDE model can be tremendously valuable. However, they also come with a drawback: they require companies to “think like an attacker.” In other words, attack trees will only contain the goals and methods that businesses themselves can conceive of.
Suppose attackers devise an entirely unexpected approach or have an unexpected objective for the attack. Companies need to anticipate these factors to be protected.
For this reason, working with so-called “ethical hackers” is an excellent idea. Ethical hackers are benevolent cybersecurity experts who use hacking techniques to help companies identify and fix vulnerabilities in their IT environment. Because ethical hackers are external to the organization, they can bring new perspectives, novel insights, and a fresh set of eyes.
The Difference Between Attack Trees and Attack Surfaces
An attack tree and an attack surface are two distinct yet closely related concepts in cybersecurity. So when it comes to the question of attack tree vs. attack surface, what’s the difference?
What Is an Attack Surface?
An attack surface is the set of points where a malicious actor could gain unauthorized access to an IT environment. The possible entry points in an attack surface include network ports, software and website vulnerabilities, and access controls. These entry points are digital, but attack surfaces also have a physical component. For example, hackers can wreak havoc by plugging in an infected USB drive or gaining physical access to a company’s server room.
Having a large attack surface is generally seen as a negative. For this reason, businesses speak of the need for “attack surface reduction” or “attack surface management.” This involves limiting the number of ways hackers could potentially exploit flaws in the environment.
Let’s continue with the safecracking example above. The attack surface would include all the components of the safe that an attacker could exploit if flaws are present. These include the lock and its combination, the physical construction of the safe, and the humans surrounding it (e.g., security guards or people who know the combination).
What Is an Attack Tree?
An attack tree is a way to partially model the attack surface by visualizing an attacker’s goal and the various methods of possibly achieving that goal. Perhaps the best way to understand the difference between an attack tree and an attack surface is the distinction between entry points and methods:
- An attack surface is a written description of the various entry points of an IT environment via which attackers could gain access and achieve their objectives.
- In contrast, an attack tree is a diagram that illustrates the attacker’s objective and the methods of achieving that objective.
Conclusion
To sum up, attack trees are an invaluable concept in cybersecurity. They help security professionals comprehend and model the threats they face by identifying potential dangers to a system or network.
By using attack trees, security professionals can better understand the various ways in which attackers could try to enter an IT system. Businesses can then develop strategies for mitigating and thwarting these threats.
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