What Is Attack Surface Management?

Introduction

Today’s security teams struggle with an ever-expanding attack surface, which is the total number of possible points where an unauthorized user can try to enter or extract data from a system. As organizations move to the cloud, adopt IoT devices, extend their infrastructure to include OT, and rely on third-party vendors, their attack surface grows exponentially.

The challenge for CISOs and security teams is ensuring that all assets are accounted for, monitored, and secured. Unfortunately, unmanaged and unknown assets often introduce serious vulnerabilities, exposing organizations to cybercriminals who exploit these blind spots. Traditional security tools often fail to provide complete visibility into these hidden risks.

This is where Attack Surface Management (ASM) becomes crucial. A robust ASM strategy empowers organizations to identify, monitor, and reduce cyber exposure by continuously discovering assets and assessing their security posture. This sense of control is invaluable in the ever-evolving landscape of cybersecurity.

However, Attack Surface Management isn’t just about external scanning; it requires deep network visibility, and this is where Corelight’s Network Detection and Response (NDR) solution plays a pivotal role. Corelight helps security teams discover unmanaged assets, detect anomalous behavior, and strengthen their attack surface defenses.

What is Attack Surface Management?

Attack Surface Management (ASM) is a continuous process that helps organizations identify, monitor, and reduce cyber risks associated with their assets. These assets include on-premise infrastructure, cloud services, SaaS applications, ICS/OT, IoT devices, and even user endpoints. ASM provides security teams with real-time visibility into all known, unknown, and unmanaged assets, helping them prevent attacks before they happen.

Types of attack surfaces

Understanding the different types of attack surfaces is key to implementing an effective Attack Surface Management strategy:

• External attack surface. These are public-facing assets such as web applications, cloud instances, APIs, and DNS services. These assets are the first point of contact for external attackers and are often probed for misconfigurations, outdated software, or exposed credentials. A single exposed API or forgotten subdomain can serve as an entry point into the organization. Attackers frequently use automated tools to scan for these vulnerabilities at scale, making visibility and continuous monitoring essential.
• Internal attack surface. This category includes endpoints, IoT devices, ICS/OT systems, and network hardware that connect to internal infrastructure. These assets may be harder to detect and monitor, especially in hybrid and remote work environments. Unmanaged or misconfigured internal devices can facilitate lateral movement once an attacker gains initial access. Organizations often struggle with maintaining visibility over internal assets due to network complexity and device proliferation.
• Human attack surface: Threats to this surface include phishing, social engineering, and insider threat risks. Employees, contractors, and third-party users can inadvertently expose the organization to risk through poor cyber hygiene or by falling victim to manipulation. Human error remains one of the leading causes of data breaches, making awareness training and user behavior monitoring essential. ASM strategies must include visibility into user interactions and access patterns to flag anomalies that could indicate compromise.

Attack Surface Management helps organizations track and secure these assets continuously, reducing the likelihood of cyber incidents stemming from overlooked vulnerabilities.

Why is Attack Surface Management critical for CISOs and security teams?

Regulatory and compliance pressures

Security leaders must ensure compliance with frameworks like NIST, CIS, GDPR, and ISO 27001, which mandate that organizations monitor and protect their digital assets. A weak Attack Surface Management strategy can lead to compliance violations, financial penalties, and reputational damage. Non-compliance also increases the likelihood of data breaches, which often trigger mandatory breach disclosures and legal scrutiny. ASM helps CISOs maintain accurate asset inventories, enforce policy controls, and generate audit-ready reports, streamlining regulatory efforts.

Lack of visibility leads to breaches

According to industry reports, most cyberattacks involve assets that security teams weren’t aware of. These could be forgotten cloud instances, unpatched servers, or unauthorized SaaS applications. Without complete visibility, security teams are left reacting to incidents instead of proactively preventing them. Attackers routinely scan for unmonitored and exposed systems, knowing these are less likely to be protected. ASM closes this visibility gap by continuously identifying and tracking assets across hybrid environments.

Key benefits of a strong Attack Surface Management strategy

A strong ASM program supports asset lifecycle management, streamlines vulnerability prioritization, and enhances collaboration between security, IT, and DevOps teams. Organizations that implement continuous Attack Surface Management are better prepared to withstand sophisticated cyber threats through:

• Proactive risk reduction. A key objective is for defenders to identify security gaps before attackers do. By continuously mapping the entire attack surface, ASM enables teams to spot misconfigurations, unknown assets, and policy violations. Early detection reduces the window of exposure and allows organizations to patch or isolate vulnerabilities before they’re exploited. ASM also empowers security leaders to prioritize risk based on asset criticality and business impact.
• Faster incident response. Knowing all assets improves investigation and containment speed. When an incident occurs, having a comprehensive inventory of assets helps responders quickly identify affected systems and contain the breach. ASM tools that integrate with SIEM or NDR solutions streamline forensic investigations by linking alerts to specific assets. This visibility eliminates blind spots and reduces time-to-resolution during critical events.
• Cost savings. Preventing breaches reduces financial losses from remediation and compliance fines. Breaches caused by unknown or unmanaged assets often incur high costs in the form of legal fees, regulatory fines, and operational downtime. ASM helps organizations avoid these costs by proactively reducing the attack surface and ensuring assets are properly secured. Additionally, asset discovery and risk scoring automation lower operational overhead for security teams.

The risk of unmanaged and unknown assets

One of the biggest security challenges today is identifying and securing unknown assets. Without proper Attack Surface Management, organizations face the following risks:

1. Shadow IT

Employees frequently deploy unauthorized SaaS applications and cloud instances, creating security gaps that go unnoticed by IT and security teams. These tools often bypass security policies, lack proper access controls, and may store sensitive data externally. As a result, security teams struggle with visibility and cannot enforce consistent protections. Shadow IT increases the chance of data leakage, compliance violations, and unmonitored data exposure.

Breach example: Okta (2023). In one notable incident, Okta experienced a breach stemming from an employee signing into a personal Google account on a work device—an act of Shadow IT that created a pathway for attackers to infiltrate internal systems.

2. Legacy systems

Old, unpatched servers and applications often become easy targets for attackers. Organizations may lose track of these assets, leaving them vulnerable. Legacy systems may not support modern security updates or integrations with monitoring tools. They often rely on outdated protocols or configurations, making them ideal entry points for attackers who exploit known vulnerabilities.

Breach example: Volt Typhoon (2023). The China-linked Volt Typhoon campaign targeted legacy infrastructure in critical industries, exploiting outdated systems with unpatched vulnerabilities to establish long-term access and avoid detection.

3. Third-party risks

Vendors and partners increase an organization’s attack surface, often introducing vulnerabilities that cybercriminals can exploit. These external entities may have access to sensitive data or internal systems, and their security practices are not always transparent. A breach in a third-party system can have a cascading effect on connected organizations. Managing these risks requires constant assessment and continuous trust evaluation.

Breach example: SolarWinds Supply Chain Attack (2020). Attackers inserted malicious code into SolarWinds’ Orion software updates, compromising thousands of organizations via a trusted third-party provider, and highlighting how third-party access can become a backdoor.

4. IoT and unmanaged endpoints

Unmonitored IoT devices and employee-owned devices (BYOD) often lack proper security controls, making them potential entry points for attackers. These devices are typically outside the direct control of IT teams and may not receive timely updates or patches. Attackers can exploit them to establish persistence or pivot to other systems within the network. The sheer volume and diversity of IoT devices further complicate visibility and risk management.

Breach example: Verkada IoT Camera Hack (2021). Hackers gained access to over 150,000 internet-connected security cameras through a misconfigured admin account, exposing footage from Tesla, jails, and schools — and showing how IoT devices can become silent vulnerabilities.

5. Forgotten or misconfigured cloud resources

Organizations frequently spin up cloud storage, VMs, or containers and forget to decommission or properly secure them, leaving them exposed. These neglected assets often lack proper access controls, encryption, or visibility within centralized security tooling. Misconfigured permissions, such as open S3 buckets or overly permissive IAM roles, are common attack vectors for threat actors. Dynamic and decentralized DevOps workflows can also lead to configuration drift, where security settings diverge from policy over time. Without continuous monitoring and inventory, these forgotten resources become low-hanging fruit for attackers scanning for exposed cloud infrastructure.

Breach example: Capital One AWS S3 Misconfiguration (2019). A former AWS employee exploited a misconfigured web application firewall to access Capital One’s S3 buckets, exposing personal data of over 100 million customers — and underscored the risks of forgotten or misconfigured cloud infrastructure.

Common misconceptions about attack surface management (from a network security perspective)

ASM has become a strategic priority in cybersecurity, but it is often misunderstood, especially when viewed through a purely perimeter-based or endpoint-centric lens. Many security teams fail to connect ASM with what’s happening inside their networks, leading to blind spots in detection and response.

Here are some of the most common misconceptions about Attack Surface Management and how Corelight helps overcome them:

“ASM is just external scanning”
A prevalent misconception is that Attack Surface Management simply means scanning internet-facing assets for exposure. While external reconnaissance is important, it only tells part of the story. In this framing, internal assets — unmanaged endpoints, rogue devices, lateral movement paths, and shadow IT — are often missed.
Corelight insight: Corelight’s NDR platform goes beyond surface-level scanning by analyzing east-west and north-south traffic, identifying internal assets and behaviors that external scanners miss. This includes discovering unauthorized SaaS apps, rogue cloud services, and newly connected devices in real time.

“ASM is redundant if I have EDR”
Endpoint Detection and Response (EDR) solutions are essential but only monitor managed endpoints, typically leaving out unmanaged assets, IoT devices, and BYOD. They also can’t track network behavior across segments or cloud-native infrastructure.
Corelight insight: Corelight fills the visibility gap left by EDR with full-spectrum traffic analysis, detecting unmanaged or agentless devices and surfacing behavioral anomalies that indicate compromise, even when endpoint agents are absent.

"ASM is only for large organizations”
Some assume Attack Surface Management is only necessary for enterprises with sprawling infrastructures and vast IT teams. However, small and medium-sized businesses (SMBs) are equally vulnerable, if not more so, due to limited security staff and constrained budgets. Cyber attackers don’t discriminate by size; they look for exposed assets and easy entry points.
Corelight insight: Corelight’s scalable architecture supports organizations of any size, from lean security teams to global SOCs. With out-of-the-box asset discovery, behavioral analytics, and integrations into existing workflows, Corelight makes enterprise-grade ASM capabilities accessible and impactful for SMBs.

“Network visibility isn’t part of ASM”
The most dangerous myth is that Attack Surface Management can be complete without network visibility. In truth, the network is where unknown assets reveal themselves — whether it’s a rogue access point, a forgotten container, or a third-party device transmitting sensitive data.
Corelight insight: Corelight turns the network into a source of truth for asset discovery and threat detection, enabling ASM that is grounded in real-world behavior and communication patterns, not just static inventories or perimeter checks.

How Corelight NDR enhances attack surface management

Many traditional Attack Surface Management tools focus on external scanning and asset discovery but miss critical internal blind spots within the network. This is where Corelight’s Network Detection and Response (NDR) solution provides deeper visibility and better attack surface monitoring.

Why traditional Attack Surface Management tools fall short

External scanners provide an inventory of public-facing assets but don’t track internal unmanaged endpoints or shadow IT. They often fail to provide context around asset behavior, making it challenging to prioritize risks effectively. These tools are inherently reactive and can miss transient assets that appear only briefly.

Configuration management databases (CMDBs) rely on manual updates, leading to outdated asset inventories. They also lack real-time responsiveness, which means new or transient assets can go unrecorded for extended periods. Security teams can’t act on stale data, and it undermines the integrity of broader risk management initiatives.

EDR solutions only monitor managed endpoints, leaving IoT devices, rogue hosts, and cloud services unseen. In addition, in most organizations, EDR coverage is about 65-70%. This leaves a large portion of the internal environment unmonitored, creating blind spots that attackers can exploit. Even where coverage exists, EDRs often miss threats originating outside the endpoint or moving laterally across the network.

Corelight’s unique approach to completing ASM

Corelight NDR helps security teams see beyond traditional Attack Surface Management tools by monitoring real-time network traffic to identify all known and unknown assets. It enables a more holistic approach to ASM by adding network-centric visibility that complements existing tools. By acting as a passive observer, Corelight introduces no friction to endpoints or infrastructure, and provides:

Real-time network visibility
Corelight analyzes all network traffic, detecting new devices and unknown assets the moment they connect. This allows security teams to build a live, dynamic asset inventory without relying on static scans or manual inputs. It ensures assets are discovered as they appear, not days or weeks later.

Identification of shadow IT and rogue devices
The platform automatically detects unauthorized cloud services, SaaS applications, and unapproved endpoints. It flags these assets based on behavioral patterns rather than relying solely on agent-based detection. This helps security teams catch misused or risky assets even when employees bypass formal provisioning channels.

Behavior-based anomaly detection Corelight uses network telemetry and machine learning to flag unusual communications that could indicate an exploited asset. This includes lateral movement, data exfiltration attempts, or communication with suspicious external domains. It helps surface threats that signature-based tools often miss.

Threat intelligence integration
Corelight matches observed network activity with known indicators of compromise (IoCs). This contextual awareness allows faster detection and response to active threats operating within the organization’s attack surface. The integration also supports proactive defense by correlating asset activity with real-world threat campaigns.

Security telemetry for deep insights: The Corelight platform generates detailed Zeek® logs and packet-level data, helping analysts quickly investigate suspicious activity. This high-fidelity data integrates easily into SIEM and SOAR platforms, enabling automated workflows and deeper threat hunting capabilities. By enriching ASM efforts with detailed context, Corelight enables faster triage and more accurate incident response.

Use case: Corelight in action

Imagine a security team using Corelight to monitor network traffic. One day, Corelight detects a new device communicating with an external IP associated with known malware. Further investigation reveals the device is an unauthorized IoT sensor deployed by a third-party vendor. Without Corelight’s ASM capabilities, this rogue device could have remained undetected, exposing the organization to serious cyber risks.

Conclusion: Gain control with NDR

As attack surfaces continue to expand, CISOs and security teams must adopt continuous Attack Surface Management to protect their organizations from cyber threats. However, traditional ASM tools alone aren’t enough; they miss internal blind spots, unmanaged assets, and real-time network threats.

Corelight’s Network Detection and Response platform fills this gap by providing deep network visibility, real-time asset discovery, and threat detection. By leveraging Corelight, organizations can enhance their ASM efforts, reduce risk, and stay ahead of attackers.

In today’s cyber landscape, attack surface management without network visibility is incomplete. Corelight ensures that security teams gain complete control over their digital footprint, detect threats proactively, and secure every asset, known and unknown.