With the shift to the cloud, the rise in software-as-a-service (SaaS) applications and a sudden increase in remote work capabilities, most organizations’ attack surface has become larger and more complex, making it exponentially more difficult to define and defend. Since virtually any asset is capable of being an entry point to a cyberattack, it is more important than ever for organizations to improve attack surface visibility across assets — known or unknown, on-premises or in the cloud, internal or external.

What is Attack Surface Management?

Attack surface management is the continuous discovery, monitoring, evaluation, prioritization and remediation of attack vectors within an organization's IT infrastructure.

While similar in nature to asset discovery or asset management, often found in IT hygiene solutions, the critical difference in attack surface management is that it approaches threat detection and vulnerability management from the perspective of the attacker. In so doing, the organization is driven to identify and evaluate risk posed not just by known assets, but unknown and rogue components as well.

What is an attack surface?

The attack surface is the term used to describe the interconnected network of IT assets that can be leveraged by an attacker during a cyberattack. Generally speaking, an organization’s attack surface is comprised of four main components:

1. On-premises assets: Assets located on-site, such as servers and hardware.
2. Cloud assets: Any asset that leverages the cloud for operation or delivery, such as cloud servers and workloads, SaaS applications or cloud-hosted databases.
3. External assets: An online service purchased from an external vendor or partner, that stores and processes company data or is integrated with the corporate network.
4. Subsidiary networks: Networks that are shared by more than one organization, such as those owned by a holding company in the event of a merger or acquisition.

It’s important to note that the organization’s attack surface will evolve over time as devices are constantly added, new users are introduced and business needs change. For this reason, organizations must continuously monitor and evaluate all assets and identify vulnerabilities before they are exploited by cybercriminals.

The Value of Attack Surface Management

By assuming the mindset of the attacker and mimicking their toolset, organizations can improve visibility across all potential attack vectors, thereby enabling them to take targeted steps to improve the security posture by mitigating risk associated with certain assets or reducing the attack surface itself. An effective attack surface management tool can enable organizations to:

• Automate asset discovery, review and remediation
• Map all assets on a continuous basis
• Quickly identify and disable shadow IT assets and other previously unknown assets
• Eliminate known vulnerabilities such as weak passwords, misconfigurations and outdated or unpatched software

What are the core functions of attack surface management?

There are five core functions of an effective attack surface management strategy:

Phase 1: Discovery

In this initial phase, organizations identify and map all digital assets across both the internal and external attack surface. While legacy solutions may not be capable of discovering unknown, rogue or external assets, a modern attack surface management solution mimics the toolset used by threat actors to find vulnerabilities and weaknesses within the IT environment. This enhances visibility across the entire attack surface and ensures the organization has mapped any asset that can be used as a potential attack vector.

Phase 2: Testing

The attack surface changes constantly as new devices are connected, users are added and the business evolves. As such, it is important that the tool is able to conduct continuous attack surface monitoring and testing. A modern attack surface management solution will review and analyze assets 24/7 to prevent the introduction of new security vulnerabilities, identify security gaps, and eliminate misconfigurations and other risks.

Phase 3: Context

While any asset can serve as an attack vector, not all IT components carry the same risk. An advanced attack surface management solution conducts attack surface analysis and supplies relevant information about the exposed asset and its context within the IT environment. Factors such as when, where and how the asset is used, who owns the asset, its IP address, and network connection points can help determine the severity of the cyber risk posed to the business.

Phase 4: Prioritization

Because the attack surface management solution is intended to discover and map all IT assets, the organization must have a way of prioritizing remediation efforts for existing vulnerabilities and weaknesses. Attack surface management provides actionable risk scoring and security ratings based on a number of factors, such as how visible the vulnerability is, how exploitable it is, how complicated the risk is to fix, and history of exploitation. Unlike penetration testing, red teaming and other traditional risk assessment and vulnerability management methods which can be somewhat subjective, attack surface management scoring is based on objective criteria, which are calculated using preset system parameters and data.

Phase 5: Remediation

Based on the automated steps in the first five phases of the attack surface management program, the IT staff are now well equipped to identify the most severe risks and prioritize remediation. Since these efforts are often led by IT teams, and not cybersecurity professionals, it’s important to ensure that information is shared across each function and that all team members are aligned on security operations.