Discover Your Attack Surface - Tips From a Cybersecurity Engineer

Photo of Sonia Anna Puton

Sonia Anna Puton

Updated May 26, 2024 • 11 min read
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In cybersecurity, your attack surface is the total sum of the different ways an attacker could access your systems and data.

The more ways an attacker has to get in, the greater your attack surface.

Attackers are constantly looking for new ways to break into systems, so you should regularly assess your attack surface and take steps to reduce it where possible. By understanding your attack surface, you can make informed decisions about how best to protect your data and systems from threats.

Learn what an attack surface is and how you can discover yours. Check out tips on how you can reduce your attack surface and make it harder for attackers to gain access to your systems.

What is an attack surface?

An attack surface is the total of an asset's vulnerabilities that could be exploited by an attacker. The larger the attack surface, the greater the potential for an attacker to find and exploit a vulnerability.

A software program has an attack surface that includes all places where an attacker could potentially enter code or data. It consists of input and output fields, files, libraries, environment variables, and more.

But the attack surface also applies to hardware devices. For example, a computer has USB ports, network ports, and other (physical and wireless) connection points vulnerable to attaching malicious devices or inserting malicious code.

The term "attack surface" is often used in security discussions to refer to the ways an attacker can potentially gain access to a system or data. Remember that not all of the vulnerabilities on an asset's attack surface will be used by attackers. However, the larger the attack surface, the greater the chances they will abuse at least one of those vulnerabilities.

When assessing security risks, consider both the size of an asset's attack surface and the severity of the vulnerabilities present on that surface. Reducing the size of the attack surface is one way to minimize overall security risks.

For example, if a software program only accepts input from a few trusted sources, its attack surface is much smaller than if it accepted input from any source. Similarly, if a hardware device only has physical connection points necessary for its operation, then its attack surface is smaller than if it had additional unnecessary connection points.

Common attack surface areas in web applications

One common attack surface area is the app's login page. Attackers often try to brute force their way into an account by guessing passwords. Another typical attack surface area is any page that allows users to input data. Attackers can try to inject malicious code into these pages to exploit the application.

To help protect your app, you should consider using security measures like two-factor authentication, behavioral challenges (like Captcha), and input validation. Keep your software up-to-date, as new vulnerabilities are constantly being discovered. Taking these precautions, you can help keep your application safe from attack.

Why is reducing your app attack surface important?

You likely know that you should keep your app's attack surface as small as possible. But why is this?

The answer is simple: the smaller your app's attack surface, the fewer opportunities for attackers to exploit vulnerabilities and gain access to sensitive data.

Ways to reduce your attack surface

There are many ways to reduce your attack surface and make it more difficult for attackers to access your systems. One way is to ensure that you have a good understanding of your application architecture. This will help you to identify potential vulnerabilities and take steps to mitigate them.

Patch management

Patch management is a process of identifying, acquiring, installing, and verifying patches for software and hardware products.

It can seem like a daunting task, but it is essential to the security of your business. By following these steps, you can ensure that your systems are up-to-date and protected against vulnerabilities.

The first step in effective patch management is to keep track of the vulnerabilities that affect your software. There are many ways to do this, but one of the most effective is to use a vulnerability management system. It allows you to track vulnerabilities, assign them to specific users or groups, and track their status.

Example patch management tools:

Once you know what vulnerabilities affect your software, you need to decide how to address them.

In some cases, it may be possible to fix the vulnerable code. In other, you may need to apply a patch provided by the vendor. Either way, it is essential to test a fix or a patch before deploying it to production.

Finally, once you have deployed a fix or patch, you need to monitor your systems closely to ensure that you properly addressed the vulnerability. If you find that a vulnerability has not been properly fixed, you need to take corrective action immediately.

Patch management is an essential part of web application security. By keeping track of vulnerabilities and applying fixes or patches on time, you can help keep your software safe from attack.

Access Control

Implementing proper access control measures can significantly reduce your application attack surface. By adequately managing who has access to what, you can make it much more challenging for attackers to gain access to sensitive data or functionality.

There are a few different ways to approach access control, but one of the most effective is role-based access control (RBAC). RBAC allows you to assign users to specific roles with defined permissions. For example, you might have a read-only role that can only view data or an admin role that can add/edit/delete data.

Another significant aspect of access control is the least privilege. This principle states that users should only have the permissions they need to do their job – no more and no less. It helps to further reduce the attack surface by ensuring that users cannot accidentally or maliciously abuse their privileges.

Implementing proper access control measures is a crucial step in securing your application. By carefully managing who has access to what, you can make it much more difficult for attackers to gain access or cause damage.

Least Privilege

Application attacks are on the rise. A recent study by Veracode found that 86% of applications have at least one high-severity security flaw. While many factors contribute to this problem, one of the most important is the concept of least privilege.

Least privilege is the practice of granting users and processes the bare minimum permissions they need to perform their jobs. By reducing the permissions of users and processes, you can significantly reduce your application's attack surface.

There are a few key ways to implement the least privilege in your organization:

  • Segment your network so that different parts of the organization have different levels of access. This way, if one part of the network is compromised, the rest will remain safe.
  • Use role-based access control (RBAC) to give different users different permissions. This way, you can be sure that only those who need access to sensitive data have it.
  • Keep track of your environment changes by performing regular audits and locating privileged accounts.

By following these best practices, you can significantly reduce your application attack surface and make it much harder for attackers to succeed.

Application allowlisting

One of the most effective ways to reduce your attack surface is by using the application allowlisting. This security measure allows you to specify which applications can run on your system and block all others. It can be a useful way to prevent malicious software from running and reduce the overall number of potential attack vectors.

There are a few different ways you can implement the application allowlisting, but one of the most popular is through group policy objects (GPOs) in Active Directory. This method allows you to centrally manage your allow lists and easily deploy them to multiple systems. Another popular approach is through third-party software, such as AppLocker from Microsoft or Whitelister from Symantec.

No matter which method you choose, the application allowlisting can be a very effective way to reduce your attack surface and improve your overall security posture.

Data Security

Minimize the amount of data that is stored and processed. The more data that is stored and processed, the greater the risk of a security breach. Therefore, it is crucial to minimize the amount of data handled by the application. Additionally, ensure that all data transmitted by the application is securely encrypted.

Popular solutions to reduce the application attack surface include data masking, tokenization, and encryption:

  • Data masking is a process of hiding sensitive data by replacing it with a non-sensitive equivalent. You can do it by substituting characters with other characters or providing null values.
  • Tokenization is a process of replacing sensitive data with non-sensitive random values called tokens.
  • Encryption is a process of transforming readable data into an unreadable format using an encryption algorithm.

When selecting a solution to reduce your app's attack surface, consider the security requirements of the application as well as the performance impact of the solution. In some cases, you may need to implement multiple solutions to provide adequate protection.

Tools to help reduce your app attack surface

There are many tools available to help you reduce your app's attack surface. Some of these tools are listed below:

  • AppScan - AppScan scans your code for vulnerabilities and provides recommendations for fixes.
  • X-Ray - a tool that helps you find hidden dependencies in your code that could be exploited by attackers.
  • Dependency Checker - the dependency Checker scans your dependencies for known vulnerabilities and provides recommendations for fixing them.
  • RetireJS - RetireJS helps you find and fix potential vulnerabilities in your JavaScript code.

For a full list of recommended tools, please visit the OWASP website.

Protect your business with the attack surface discovery process

Cybersecurity is a complex and ever-evolving field, and your attack surface management is just one aspect to consider. However, by understanding your attack surface and taking steps to reduce it, you can make your systems and data more secure.

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Sonia Anna Puton

Sonia is a Cybersecurity Engineer specializing in networks and cloud security.
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