What Is an Attack Surface and 7 Ways to Minimize It

An organization’s attack surface encompasses the entire area of a system or network that is vulnerable to cyber attacks. It includes all externally visible systems and therefore all potential entry points for unauthorized users to infiltrate the network. Once inside a network, a malicious user can exfiltrate or manipulate data or escalate their position to carry out further attacks and damage the organization.

A smaller attack surface is easier to protect, so minimizing the attack surface is an important part of an organization’s security strategy. The first step toward reducing the surface is to analyze the existing network and identify points of weakness. The organization can then implement a protection strategy to minimize the risk of a costly cyber attack.

This is part of a series of articles about cyber threats.

Attack Surface vs. Attack Vector

Attack vectors are cyber attack techniques that exploit a system vulnerability that allows the hacker to access the target network without authorization. Attackers usually collect sensitive data from their victims for financial gains, such as to extort the target organization.

An attack surface encompasses all the possible attack vectors that hackers can use to infiltrate the computer system or network and steal data. The limits of the attack surface are the overall number of exploitable vulnerabilities — e.g., the total number of data access and extraction points and every exposed system element.

Attack vectors can result in a data breach when utilized, where unauthorized individuals or hacker groups access confidential, sensitive, or otherwise protected data.

Types of Attack Surfaces

An attack surface can include physical or digital access points or human vulnerabilities.

Physical Attack Surfaces

An organization’s physical attack surface is the physical environment housing its assets, such as the server room, data center, and branch offices. Attackers can access sensitive machines and perform malicious actions when they enter a protected building or room. This approach is most common among disgruntled employees (malicious insiders), intruders, and hackers who use social engineering techniques to access physical assets.

Physical attack methods may include:

• Installing malware on target devices.

• Accessing and exposing confidential data.

• Infiltrating workstations to access source code.

Digital Attack Surfaces

A digital attack surface covers all digital elements that may allow unauthorized users to access an organization’s network. Examples include servers, ports, applications, websites, system access points, and code. The digital attack surface contains all vulnerabilities relating to exposed APIs, weak passwords, poorly maintained software, and insecure coding.

Any endpoint outside the network firewall that can access the system via the Internet is also part of the digital attack surface. Generally easier to infiltrate than a physical attack surface, many cybercriminals prefer to exploit poor cybersecurity controls to gain unauthorized system access.

An attack surface usually includes three types of digital assets:

• Known assets — All inventoried and managed assets like websites, servers, and dependencies. These are easy to identify and track.

• Unknown assets — All assets outside the security team’s view, also known as shadow IT—these range from software installed independently by employees to forgotten sites.

• Rogue assets — All malicious assets created by a threat actor, including typo-squatted websites, domains, or mobile applications that impersonate the target company. Malware also falls under this category.

Human Attack Surfaces

The human attack surface is an organization’s most vulnerable point. Many cyber attacks exploit employees, for example, with social engineering techniques. Hackers may target users for their credentials, especially if they have access privileges to sensitive systems, applications, and networks. Malicious actors can also steal corporate and personal devices.

Attack Surface Assessment Technologies

The following tools allow organizations to identify and evaluate their attack surfaces.

1. Cyber Asset Attack Surface Management (CAASM)

CAASM solutions help security teams address vulnerability management challenges and visibility of persistent assets. It works by integrating APIs with existing tools. CAASM allows cybersecurity professionals to make queries against consolidated data, assess the scope of security vulnerabilities, identify gaps in the organization’s defenses, and apply fixes. CAASM solutions don’t provide a source for records; rather, they aggregate data from various external sources.

2. Digital Risk Protection Service (DRPS)

A DPRS is a fully managed service that provides digital risk protection (DRP) capabilities. It helps address the demand for scalable DRP solutions. DRPS services augment the capabilities of third-party security teams by providing sophisticated threat detection. Organizations can leverage these capabilities to eliminate the need to maintain an in-house security team, which can be expensive and is often less flexible. Thus, a DRPS makes it easier to scale an organization’s DRP efforts.

A digital risk protection service helps organizations achieve their business goals, protect the outward-facing parts of the IT ecosystem, and ensure secure, uninterrupted access to digital technologies.

3. External Attack Surface Management (EASM)

EASM solutions use technologies and processes to automate the discovery of all assets exposed to the Internet. They help provide visibility and identify vulnerabilities associated with external servers, credentials, and software. EASM is useful for many practical purposes in a modern ecosystem because it doesn’t require integration with other processes and tools and can work without penetrating the network.

Best Practices for Attack Surface Management

To reduce their attack surface, organizations must first understand what comprises the attack surface. Attack surface assessments should reveal the known and unknown aspects of the software environment, providing more in-depth visibility into potential vulnerabilities.

The key principle for ensuring security is focusing on proactive measures rather than on defensive actions to mitigate attacks and recover from the damage. Here are some best practices to ensure effective attack surface management.

4. Implement Firewalls and Encryption

Organizations should start with basic security controls like firewalls to reduce the attack surface. For example, every open TCP port represents a vulnerability, so the firewall should restrict the number of TCP ports that outsiders can access. Another important task is to apply the latest security patches and updates. All communication should be encrypted with SSL and HTTPS certificates.

5. Remove Unneeded Code, Applications, and Modules

Depending on the specific environment, it is usually possible to limit the amount of exposed code, to reduce the opportunities for attackers to exploit it. Less code means less risk of vulnerabilities.

When applications mature and incorporate more features, the key modules usually add more functionality. Developers should hide unused parameters and eliminate dead code to minimize what an attacker can target. If no one uses a parameter, the team should consider removing it.

Another way to reduce the attack surface is to avoid using too many third-party apps — these are often risky because their source code is widely available. The team must carefully test and review the code when using a third-party application to avoid introducing third-party vulnerabilities.

6. Eliminating Entry Points

Another way to control the attack surface is to restrict the features that are accessible to external users. For example, only authorized users and registered customers should access intranet modules or online demos that expose code. Administration and content management modules should also have access restrictions.

Additional measures to limit the number of accessible entry points include:

• Enforce IP restrictions

• Use client certificates and obscure ports and client certificates

• Keep admin modules on an isolated site

• Validate and sanitize the input in web forms (this prevents SQL injection attacks)

• Only collect necessary data

• Anonymize sensitive data wherever possible

• Ensure secure uploads by limiting the types of files users can upload and only allowing authorized users to upload

• Implement cloud workload protection to enhance cloud security (this helps protect against breaches in cloud workloads and containers)

7. Eliminating Redundant Functionality

New digital assets like operating systems and servers usually require configuring. Default configurations often turn on all application services and open all ports. Another reason to configure assets is to ensure ports and applications have the necessary updates — otherwise, they can present a vulnerability.

The security process should include reviewing all digital assets and disabling unnecessary functions, services, or applications. By minimizing the attack surface and eliminating redundancy, malicious actors will have a harder time infiltrating the environment.

Related content: Read our guide to attack surface analysis