An attack surface is the sum total of all the various ways that a cyber threat actor could attack an organization. This includes everything from software vulnerabilities, like SQL injection, to lost and stolen devices to social engineering attacks against the organization’s employees or third-party partners.

An organization’s overall attack surface can further be divided into its external and internal attack surfaces. The external attack surface includes the elements of its digital attack surface that are accessible via the public Internet. This includes:

• Public-facing web applications and APIs.
• Open network ports.
• Email and social media.
• Remote access systems, such as VPNs.
• Cloud infrastructure.

An internal attack surface includes those vulnerabilities that could be exploited by an attacker who already has access to an organization’s internal systems. Examples include:

• Internal applications and APIs.
• User devices.
• Network infrastructure.
• Databases.

The importance of reducing your attack surface

An organization’s attack surface includes all of the potential ways that an organization can be targeted by an attacker. Reducing this attack surface makes a cyberattack more difficult and decreases an organization’s cyber risk exposure.

By decreasing its external attack surface, an organization increases the difficulty of gaining initial access to its environment. Most threats originate from outside the business, and gaining an initial foothold is an important first step in a cyberattack. Eliminating some attack vectors from the corporate attack surface reduces the attacker’s options for achieving initial access and carrying out their attack objectives.

Reducing an organization’s internal attack surface decreases the threat that an attacker with this access poses to an organization’s systems. Often, an attacker’s initial foothold in a corporate environment is on a low-value system (such as a user workstation or public-facing webserver), forcing lateral movement through the corporate network to their intended objective. By decreasing the collection of attack vectors an intruder can use to perform this lateral movement, an organization lowers their probability of success and increases their likelihood of being detected.

Challenges of attack surface reduction

Reducing attack surfaces is a common goal of corporate security programs. However, these efforts face various challenges, including:

• Distributed Deployments: Many companies have multi-cloud deployments consisting of infrastructure scattered across on-prem and multiple cloud environments. The distribution and diversity of these environments increase the difficulty of securing these environments and enforcing consistent policies throughout the enterprise.
• Growing Vulnerability Numbers: Since 2017, more new vulnerabilities have been discovered in production software than in the previous year, and 2024 had more new vulnerabilities than in 2017 and 2018 combined. This rapid growth in the number of vulnerabilities can overwhelm security teams and result in vulnerabilities being left unpatched and open to attack.
• Cloud Misconfigurations: The rise in cloud adoption has coincided with a rise in shadow IT as unauthorized cloud tools and resources are used for business purposes. Securely configuring cloud infrastructure is a common challenge, and this problem is exacerbated when cloud-based resources are deployed without the knowledge or guidance of the IT and security teams.
• Third-Party Risk: Many organizations have trusted partners with access to their environments or that they rely upon for key services. These partners are also part of an organization’s attack surface, but these threats can be difficult to monitor and manage.

Best practices for attack surface reduction

Attack surface reduction involves identifying and addressing potential attack vectors in an organization’s environment. Some best practices for accomplishing this include the following:

• Performing Continuous Monitoring: An organization’s attack surface can change at any time as new software is deployed and existing solutions are updated or reconfigured. Continuous monitoring provides up-to-date visibility into potential attack vectors and ensures that security personnel focus remediation efforts on the highest-risk attack vectors.
• Applying Updates Promptly: Many attack vectors in an organization’s digital attack surface involve vulnerabilities for which patches are available. Promptly applying updates when they are released reduces the risk of falling prey to these publicly known security issues.
• Implementing Least Privilege: The principle of least privilege specifies that a user or application should only have the rights and access needed to do their job. Implementing least privilege decreases an organization’s internal attack surface because an attacker can only exploit vulnerable systems that they can access.
• Segmenting Corporate Networks: Network segmentation breaks the corporate network into discrete pieces based on business role and potential sensitivity. Implementing network segmentation increases the difficulty for an attacker to move laterally through a corporate network without detection.
• Deploying Zero Trust: The zero trust security model builds on least privilege access by adding explicit verification of every access request. By eliminating implicit trust in insiders, zero trust makes it easier to detect unauthorized access requests for corporate resources or attackers’ attempts to move laterally through the corporate network.
• Educating Employees: Social engineering attacks, such as phishing, are an important part of an organization’s attack surface. Educating employees about these threats and the risks of shadow IT reduces the set of potential attack vectors that can be used to target the business.

Attack Surface Reduction with IONIX

Attack surface reduction begins with achieving visibility into an organization’s attack surface. With continuous monitoring, security teams can be made aware as new attack vectors emerge and prioritize their efforts to ensure that the most significant threats are addressed first.

IONIX automatically maps an organization’s digital attack surface, identifying potential attack vectors across SaaS, cloud services, APIs, and other IT assets. It also maps out digital supply chains, identifying sources of critical services and third-party components. To find out how IONIX can provide your security team with the intelligence needed to effectively manage your digital attack surface, sign up for an IONIX demo.