Attack surface management explained
ASM is the practice of maintaining continuous visibility into an organization’s attack surface - the sum of all systems, services, identities, and technologies that could be targeted by an attacker.
This includes on-premises infrastructure, cloud workloads, SaaS applications, internet-facing assets, third-party integrations, and shadow IT. Unlike point-in-time inventories or periodic scans, ASM is continuous by design, reflecting how quickly modern environments change.
Forrester defines ASM as the process of continuously discovering, identifying, inventorying, and assessing the exposure of an organization’s IT asset estate. In practice, ASM helps security teams answer three critical questions:
- What assets exist today?
- Which of those assets are exposed or vulnerable?
- Which exposures represent the greatest risk right now?
Without this visibility, organizations are left with blind spots - assets they don’t know exist, vulnerabilities they can’t prioritize, and risks that remain unaddressed until attackers find them first.
To understand ASM fully, it helps to start with the concept of an attack surface itself - the collection of potential entry points attackers may attempt to exploit across your environment.
Why is attack surface management important?
Attack surface management is important because it gives security teams the visibility, context, and prioritization needed to address vulnerabilities before they are exploited.
Modern organizations face constant change: New cloud resources are deployed, SaaS tools are adopted without security review, identities are created and modified, and third-party services are integrated into critical workflows. Each change expands the attack surface, often without clear ownership or oversight.
Effective ASM helps organizations:
- Improve visibility into known and unknown assets across cloud, SaaS, and on-prem environments.
- Add context to exposures by understanding how assets are configured, connected, and accessed.
- Prioritize risk so teams focus remediation efforts on what matters most, not just what is easiest to find.
By making attack surface risk visible and understandable, ASM also helps align IT, security teams, and leadership around shared risk priorities and more informed decision-making.
Key challenges of attack surface management
Managing an attack surface is difficult because it is constantly evolving. Some of the most common challenges organizations face include:
Distributed IT ecosystems
Traditional network perimeters no longer exist. Cloud services, remote workforces, and hybrid environments mean assets are distributed across regions, providers, and platforms. This makes it difficult to monitor and secure everything using perimeter-based approaches alone.
Siloed teams and ownership gaps
Attack surface visibility often spans multiple teams — security, IT, cloud, DevOps, and third parties. When responsibilities are fragmented, critical exposures can fall between teams or go unaddressed due to unclear ownership.
Continuous change and asset sprawl
New assets appear daily, while others are modified or decommissioned without documentation. Unknown or unmanaged assets are especially risky, as they may be exposed to the internet, misconfigured, or unpatched.
These challenges are especially pronounced for external-facing assets, which is why many organizations incorporate external attack surface management (EASM) as part of a broader ASM strategy.
What are the core functions of attack surface management?
While implementations vary, most attack surface management programs include several core functions that work together to reduce risk.
Discovery
Discovery focuses on identifying all assets that make up the attack surface, including systems that may not be fully documented or intentionally deployed. This can include cloud workloads, SaaS applications, identities, endpoints, and third-party resources.
Because attackers actively look for unknown or forgotten assets, discovery must be continuous rather than periodic.
Testing
Testing evaluates whether discovered assets contain vulnerabilities or weaknesses that could be exploited. This may include techniques such as dynamic application security testing (DAST), static application security testing (SAST), and penetration testing.
Regular testing helps organizations understand not just what assets exist, but how they could be compromised.
Context
Context adds meaning to raw findings. Not all vulnerabilities carry the same risk, and not all assets are equally important.
Contextual information — such as public exposure, business criticality, identity permissions, and threat intelligence — helps security teams understand which issues pose the greatest real-world risk.
Prioritization
Prioritization ensures teams focus remediation efforts where they will have the greatest impact. Rather than chasing every vulnerability, ASM programs emphasize addressing exposures that are most likely to be exploited and most damaging if compromised.
Effective prioritization is essential for reducing alert fatigue and making limited security resources more effective.
Remediation
Remediation is the process of reducing or eliminating risk by fixing vulnerabilities, tightening configurations, removing unnecessary exposure, or decommissioning unused assets.
As environments grow, remediation must scale with them. Automation and repeatable workflows are often key to maintaining progress over time.
Attack surface management vs. CAASM vs. EASM
Attack surface management is often discussed alongside related approaches such as CAASM and EASM. While these concepts overlap, they serve different purposes.
Attack surface management (ASM) is the broad discipline focused on discovering, understanding, and reducing exposure across the entire attack surface - internal and external.
Cyber asset attack surface management (CAASM) focuses specifically on internal asset visibility and relationships, helping organizations understand how devices, identities, applications, and services connect across complex environments.
External attack surface management (EASM) concentrates on assets exposed to the public internet, such as domains, IP addresses, cloud services, and third-party-facing systems that attackers can directly see and target.
In practice, organizations often use these approaches together to gain a more complete understanding of exposure and risk.
How attack surface management supports exposure management
Attack surface management plays a foundational role in modern exposure management strategies.
By continuously identifying assets, vulnerabilities, and misconfigurations, ASM provides the visibility needed to assess exposure. When combined with risk context, threat intelligence, and prioritization frameworks, this visibility helps organizations move from reactive security toward proactive risk reduction.
In exposure management programs, ASM enables teams to understand not just where vulnerabilities exist, but how attackers could realistically exploit them and which paths pose the greatest risk to the business.
Related reading
Cyber Asset Attack Surface Management 101
Understanding your attack surface: Different approaches to asset discovery
The importance of asset context in attack surface management