What is External Attack Surface Management (EASM)?

External Attack Surface Management is an all-inclusive security approach dedicated to finding, managing, and reducing risks related to internet-facing assets. Organizations today own and rely upon a whole gamut of assets that do not just lie behind their traditional network boundaries but extend far and beyond into web applications, cloud services, mobile APIs, and third-party platforms. Each of these external-facing assets presents potential entry points for cyber threats and malicious actors and, thus, significantly complicates the task of security teams in monitoring, securing, and controlling the risks arising outside their direct internal networks.

The attack surface multiplies many times with companies embracing cloud-based services, digital transformation strategies, and remote work capabilities. This spread attack surface needs solutions in EASM to ensure continuous and real-time visibility of all potential external assets with possible vulnerabilities. The view by EASM for security posture is from an outside-in view where the digital footprint of an organization is perceived from the perspective of a hypothetical attacker. This proactive approach will help a business identify and correct their weaknesses prior to when their weaknesses can be exploited, giving them the likelihood to avoid breaches and strengthen the security of their external digital environment.

The Attack Surface Management (ASM) space is rapidly growing; Gartner named attack surface expansion its top trend in cybersecurity for 2022. Technologies like Digital Risk Protection Services (DRPS), External Attack Surface Management (EASM), and Cyber Asset Attack Surface Management (CAASM) are becoming essential tools for CISOs. These solutions help visualize internal and external business systems, automating the discovery of security gaps and supporting a more comprehensive view of organizational risks.

This article explores the essentials of External Attack Surface Management, its importance in modern security practices, and actionable steps for building an effective EASM program.

What is External Attack Surface Management (EASM)?

External Attack Surface Management is a set of processes and tools designed to monitor and secure an organization’s internet-exposed assets. Unlike traditional security solutions that focus on internal defenses, EASM operates from an external perspective, viewing an organization’s digital footprint as a potential attacker would. By continuously scanning the internet for assets related to an organization, EASM helps to discover and manage vulnerabilities before they can be exploited by malicious actors.

Why is EASM Critical?

EASM is much needed today because most organizations have adopted cloud technologies, remote work models, and complex third-party integrations that have expanded the attack surface of most organizations. Existing security controls typically only target traditionally defined internal assets without assuring proper protection for an organization’s external-facing elements such as cloud services, web applications, and APIs.

It provides visibility into such external assets as EASM allows discovery, monitoring, and management of these external risks proactively. Continuously monitoring in real-time, EASM minimizes security blind spots, promotes regulatory compliance, and reduces the probability of data breaches and cyber attacks, protecting an organization against evolving external threats.

Features of External Attack Surface Management (EASM)

Solutions from EASM enable organizations to track and safeguard their external digital assets by providing several features. These are integrative features that come together to support holistic visibility, assessment, and prioritization regarding the risks of internet-exposed assets, which enables security teams to maintain control over their attack surface. Here’s a closer look at these essential features of a robust EASM solution:

1. Asset Discovery: One of the fundamental capabilities of EASM is asset discovery. It simply means the identification and cataloging of all the internet-facing assets of an organization. This may include tracking the IP addresses, domains, subdomains, web applications, cloud instances, or any such digital asset exposed to the internet. This helps to give EASM a complete inventory of these external assets, thereby giving an all-rounded view of the organization’s footprint externally. Thus, it helps to reveal unnoticed shadow IT and third-party assets by internal IT and security teams.
2. Vulnerability Assessment: EASM solutions conduct an in-depth vulnerability scanning on the discovered assets to identify security gaps, misconfigurations, and outdated software that could leave an organization vulnerable to potential attacks. This scanning includes recognition of weak points such as exposed ports, insecure configuration, and also unpatched software which become one of the most common vectors for cyberattacks. Flagging such vulnerabilities will help EASM assist organizations in pinpointing weaknesses in their external assets before being exploited by hackers.
3. Threat Intelligence Integration: EASM solutions often integrate threat intelligence feeds to enhance the security context of each asset, thus allowing the enriched data to provide indications for the likelihood and severity of potential threats, which allows organizations to understand which vulnerabilities are being actively targeted by threat actors. Risk-level contextualization comes through assessing the asset’s exposure against known or emerging threats, which further supports more informed decision-making in managing and mitigating risks.
4. Continuous Monitoring: EASM solutions provide continuous, real-time monitoring of an organization’s external attack surface. Unlike a periodic scan, it detects changes to the attack surface-new assets added, changes to existing assets, and changes in exposure for those assets right away. Continuously on the watch ensures the new creation or modifications of internet-facing assets are recognized and accounted for while keeping up with the dynamic character of the attack surface and timely risk detection and remediating.
5. Risk Scoring and Prioritization: EASM lets the organizations score risks against each asset according to the severity of identified vulnerabilities, as well as exposure levels and threat intelligence insights. Risk scoring and prioritization, therefore, help security teams focus on the highest-value assets first and limit the use of rather limited resources in the best possible manner. Using the EASM may help to rank risks in order of priority to optimize efforts toward threat mitigation, potentially reducing exploitation and increasing the overall security posture.

Internal vs. External Attack Surface Management: Critical Differences

• Internal Attack Surface Management focuses on managing and protecting assets that sit within its network perimeter-things like servers, workstations, databases, and all other internal infrastructure. It essentially focuses on strategies that give access control, patch management, endpoint protection, and network security to curtail unauthorized access and vulnerabilities within the given network.
• On the other hand, External Attack Surface Management (EASM), refers to those assets reachable from outside the organization, such as web applications, cloud resources, APIs, and domains exposed over the internet. EASM does provide “an attacker’s view” of the organization, by covering security-specific risks as pertain to assets, which are easily accessible from a distance but less visible to internal security tools. Focusing on external elements exposed to attackers, EASM can identify external vulnerabilities and actual threats against the organization’s security capabilities, supplementing internal security controls.

Key Elements of External Attack Surface Management

An EASM strategy will encompass multiple things, all of which will allow for inclusive visibility, real-time risk management, and proactive threat mitigation. It accompanies the coverage of comprehensive asset inventory.

1. Comprehensive Asset Inventory: Keeping an updated inventory of all outward-facing assets is very much the center of comprehension and management of the attack surface. Examples include domains, IP addresses, cloud services, web applications, and other Internet-facing assets related to the organization. An asset inventory of this nature helps security teams in tracing shadow IT and third-party resources that can potentially introduce unknown risks within the organization.
2. Real-Time Monitoring and Detection: Continuous scanning in this case is essential in as much as the evolution of the attack surface may be noticed instantaneously. Real-time scanning of the internet by external attack surface management tools can thus spot new or modified assets and raise alarms as regards newly introduced vulnerabilities. It can thus spot changes as they occur and raise an alarm in case of a change that introduces potential risks or makes an organization vulnerable to potential threats.
3. Risk Assessment and Prioritization: Good risk assessment and prioritization capabilities in effective EASM enable an organization to focus efforts on the most important risks. In EASM, for every vulnerability, it assigns risk scores according to their severity and their likelihood, which helps security teams to utilize their resources more effectively, as they can tend to fix high-risk assets before they become worse.
4. Automated Remediation: The attack surface is constantly evolving, and remediation cannot be achieved without the ability of automation for remediation. Exposures and vulnerabilities trigger immediate automation response, including patching and changing configurations, and resetting permissions. It also scales remediation efforts while transferring the focus of security teams to more complex or strategic tasks.
5. Reporting and Analytics: Detailed reporting and analytics help organizations make informed decisions about their external attack surface. Tracking risks, asset changes, and remediation in detail should ensure this. Dashboards and reports in the EASM solution will help security teams and decision-makers review trends of their attack surface, understand the degree of effectiveness that security measures may have in place, and take on an informed direction on future security strategies. Such insights are critical in demonstrating compliance with regulatory standards as well as measuring a global security posture.

How Does EASM Work?

Solutions developed in EASM provide optimum functionality using automated scanning, data aggregation, and threat intelligence to always find and determine external digital assets by constant periodic searches.

Several critical steps in this regard focus on finding and closing as many potential vulnerabilities as possible:

1. Asset Discovery: EASM is based on asset discovery where tools make use of search engines, OSINT, and proprietary data sources to extract all internet-facing assets related to the organization. This consists of domains, IP addresses, cloud services, APIs, and other resources. Mapping these assets provides a thorough look into the external digital footprint of an organization which might otherwise go untracked by internal teams.
2. Vulnerability Identification: The tools scan the mapped assets and look for known vulnerabilities, misconfiguration, open ports, insecure endpoints as well as unpatched software. It is one of the vulnerability identification steps whereby entry points are revealed to attackers that might be used to breach the organization in case of planning ahead and seeing the risks early enough for their remediation.
3. Threat Detection: This integrates EASM into threat intelligence feeds. Through comparison of real-time threat intelligence and assets and vulnerabilities, external attack surface management tools can select high-risk indicators, such as those vulnerabilities actively exploited within current attacks. This will put in context for the security teams what threats are more critical, thus enabling them to start with critical vulnerabilities first.
4. Continuous Assessment: EASM continuously scans the external-facing attack surface and immediately notifies of any change, newly discovered asset, or emerging exposure. With continuous assessment, changes in the type of new cloud instances or changes on web applications are immediately identified, thus allowing the organization to make assessments and act on those changes from the time they are identified.
5. Remediation Recommendations: EASM tools, based on risk levels and potential impacts, prioritize remediation actions so as to enable the organizations to better plan and resource where remediation is most required. It streamlines the response process by enabling the team to mitigate vulnerabilities based on severity and potential impact on the organization.

How to Build an Effective EASM Program?

There is a structured approach that combines asset visibility, continuous monitoring, threat intelligence, and proactive response capabilities for the proper design of an effective EASM program.

Some of the major steps involved in establishing a robust EASM program are as follows:

1. Identify and Inventory Assets: Begin by conducting a comprehensive discovery process to establish a baseline inventory of all external-facing assets. This asset inventory serves as the foundation of the EASM program, ensuring that all potential attack vectors are accounted for and monitored.
2. Implement Continuous Monitoring: Develop continuous processes for scanning the external environment to identify new assets, vulnerabilities, and threats upon emergence. Continuous monitoring will enable an organization to have real-time visibility into change and the capacity to respond in real time to dynamic risk.
3. Integrate Threat Intelligence: Re-create asset information using real-time feeds from threat feeds to input contextual background about potential threats and means of exploitation. Threat intelligence integration supports better risk profiling and prioritizing that determines which vulnerabilities must be remediated first.
4. Prioritize Remediation Efforts: Use risk scoring and prioritization to identify the most risky assets and vulnerabilities to focus on first. Attacking at the highest-risk levels will maximize resource usage and minimize the likelihood that your really important assets are exposed.
5. Develop an Incident Response Plan: Design an externally facing-specific incident response plan that delineates escalation paths, communication strategies, and roles for the members involved. The incident response plan prepares an organization to quickly and effectively respond to incidents that have an effect on its assets facing the outside world.
6. Regularly Update Policies: Ensure updated security policies and procedures that will include changes both within the organization’s digital assets and new external threats. Proper alignment results in an EASM program that is on time yet shockproof to new onsets.

Benefits of Implementing an EASM Strategy

Utilizing an EASM strategy can serve to deliver significant benefits to organizations in terms of security, operations, and finances. Collectively, these serve to enable the organization to better safeguard itself against threats from external sources, protect its sensitive information, and ensure optimal utilization of security resources.

Here’s an elaborate overview of the major benefits of using an EASM strategy:

• Enhanced Visibility: EASM offers an outside-in perspective, hence an organization can see its entire internet-facing assets, including those shadowed IT, third-party platforms, and unmanaged resources. Total scope visibility is needed to understand and manage the external attack surface, which is usually bigger than anticipated due to new cloud services, efforts on digital transformation, and dependencies on third parties. Knowing exactly what assets exist and where they reside enhances the evaluation and security of all possible entry points, therefore strengthening the overall security posture.
• Proactive Threat Mitigation: EASM empowers security teams to take an active stance in threat management by identifying vulnerabilities early. The EASM tools allow teams to scan external assets and their exposures and weaknesses for remediation purposes before being targeted or exploited by attackers. This means that enhanced detection capabilities significantly reduce the chance of a successful cyberattack; thus, organizations can also minimize probable damages and ensure business continuity. Threat hunting as a proactive threat mitigation also inspires a preventive culture in which teams continually strive to outpace threats rather than waiting until breaches happen.
• Reduced Attack Surface: Continuous monitoring along with remediation continuously minimizes an organization’s external attack surface over time. For every weakness or exploitable condition of the system discovered, these hackers have a possible entry point to carry out their attacks. Scanning and repetition reduce the attack surface through risk prioritization and remediation offered by the EASM tools, such that the organizations reduce available assets in malicious actors’ hands. This continuous shrinkage of exposed assets translates to fewer potential attack doors, thus making it extremely difficult for hackers to break into the virtual space of the organization.
• Improved Compliance: EASM is one of the assets that may be helpful in realizing the regulatory requirements and standard compliance by maintaining data protection and risk management. Most of these regulations such as GDPR, HIPAA, and PCI-DSS require any company to track, protect, and document all its assets, but with a focus on the internet-facing ones. EASM contributes to meeting these requirements through regular scanning and reassessment of external assets, detailed reports, and efforts to safeguard the data along with the security requirements. This compliance assistance merely enables an organization to decrease its possibilities of penalties, but this develops trust among customers as well as partners.
• Cost Efficiency: EASM strategy will minimize the chances of expensive security incidents significantly because it provides an organization with the opportunity to know about its vulnerabilities proactively. This is significantly less expensive than the recoveries following an attack, in terms of financial and reputational losses, recoveries, legal fees, fines, and loss of customer trust. More importantly, EASM provides the means by which security resources can be better organized in terms of streamlining activities based on priorities of assets and vulnerabilities in order to provide effective time and budget allocation to the most critical areas.

Top Challenges in External Attack Surface Management

While EASM does provide significant security value, the implementation and management of an EASM solution with best practices prove to be challenging for most organizations. These should be managed for optimal EASM performance and a strong cybersecurity posture.

1. Shadow IT: Shadow IT refers to any IT systems, software, or services that are used within an organization without explicit approval or oversight from the IT department. Shadow IT assets include unauthorized cloud accounts, applications, and devices. These pose considerable risks since they often don’t make an appearance on typical asset lists. Since such assets remain unseen they are neither monitored nor protected against attack.
2. Asset Identification: Detection and classification of all external assets regardless of whether they are internally developed or outsourced by third parties, contractors, or legacy systems is relatively complex. EASM solutions should be able to detect unavailable or unaccounted assets in different cloud environments, third-party vendors, or old systems in an organization that might not easily identify them. Different techniques should be used to ensure that all external assets are properly inventoried so that unmanaged entry points are reduced.
3. False Positives: Automated scanning is an essential component of EASM, but sometimes it produces false positives, resulting in unnecessary alarms and significant work for security teams. False positives can be extremely common, leading to alert fatigue or security teams becoming lax so that they might fail to identify genuine threats in the future. The best EASM solutions must significantly minimize false positives and deliver a clean system to identify real threats from softer issues.
4. Complexity in Risk Prioritization: Organizations usually face challenges in prioritizing remediation efforts because the risk levels for different types of vulnerabilities vary. Without clear frameworks on risk prioritization, resources may not be appropriately spent, and time and effort can go to waste on low-risk issues while the most critical vulnerabilities are left unsolved. High-risk assets must therefore be targeted for action by a robust risk assessment methodology that guides security teams.
5. Scalability: As organizations grow and scale, so does their digital footprint, thereby expanding the external attack surface, making it bigger and more complex. Therefore they require EASM solutions that are scalable to be extended across new assets, locations, and services, with constant monitoring and protection. Scalability is a need for most organizations when adopting new technologies, expanding into new markets, or dynamic cloud environments, and therefore, in all these continue to expose themselves to increased external threats consistently.

Best Practices for External Attack Surface Management

To make EASM more effective, organizations should adopt best practices that foster proactive management, effective resource utilization, and continuous improvement in the following aspects:

1. Regular Asset Discovery: Conduct periodic asset discovery scans to ensure all external assets, including new or recently modified ones, are detected and added to the inventory. Regular discovery helps to catch changes in the external environment, including assets created without IT knowledge, reducing the risk of shadow IT and keeping asset records accurate and up-to-date.
2. Automate Monitoring and Alerts: Automating monitoring and alerts reduces the manual workload and ensures timely changes in the external environment. Routine scanning, vulnerability alerts, and real-time tracking of new assets help improve the responsiveness of security teams toward threats and their mitigation better before they become more significant.
3. Incorporate Threat Intelligence: Adding real-time threat intelligence to EASM will allow an organization to contextualize risk based on up-to-date threat data. Threat intelligence can enable the prioritization of vulnerabilities by showing which vulnerabilities are actually being actively exploited or targeted, thereby guiding more focused remediation efforts.
4. Integrate with Vulnerability Management: EASM should, therefore, integrate with vulnerability management tools to show an all-rounded security approach. This integration ensures security teams track both internal and external vulnerabilities from one source; hence, visibility is enhanced and supports more cohesive risk management of the entire digital ecosystem across the organization.
5. Review and Update Policies Frequently: The more a digital transformation initiative progresses, the more the external attack surface advances. It is thus imperative that security policies be reviewed and updated at regular intervals, especially following new digital initiatives, acquisitions, or changes in cloud usage. Keeping such policies updated ensures appropriate alignment with the most current security requirements and digital assets, hence keeping the organization ready to stand as a resilient exterior threat.

Considerations for Choosing an EASM Tool

The selection of an EASM tool should ensure that the solution is comprehensive, scalable, and adaptable to meet the emerging digital and security needs of an organization. Some considerations are as follows:

1. Comprehensive Coverage: A good EASM tool encompasses all the broad external assets such as domains, IP addresses to cloud services, APIs, and third-party systems. It is essential for this full coverage to avoid blind spots that will allow the security team to track the whole external attack surface. It is very important in such organizations with a lot of digital products, and all their internet-exposed components are under constant surveillance.
2. Scalability: Organizations often expand their digital environments through new cloud services, partnerships, and acquisitions. A scalable EASM tool can grow with the organization, accommodating additional assets, cloud environments, and remote offices without sacrificing performance. Scalability helps ensure that as the organization’s attack surface grows, security teams maintain consistent visibility and control.
3. Integration Capabilities: Integrating the EASM tool with other security solutions—such as SIEM platforms, vulnerability management systems, and incident response tools—streamlines workflows and centralizes monitoring. This integration supports coordinated alerting and response, reducing the time to detect and respond to threats. For instance, EASM integration with an SIEM can correlate external asset alerts with internal threats, providing a more comprehensive view of the security landscape.
4. User-Friendly Interface: Having an intuitive interface and customizable dashboards means that security teams can quickly access and analyze critical information. A user-friendly design can minimize training time with new users as well as reduce alert fatigue since teams are only focused on high-priority threats. Ease of use provides assurance that security professionals can sufficiently employ the tool’s functionality to monitor and protect external assets.
5. Threat Intelligence Enrichment: Threat intelligence gives flesh to the bones of risks, helping teams to prioritize vulnerabilities based on active, known threats. EASM tools that integrate threat intelligence provide real-time information on emerging risks, such as threat actor activity; exploit trends; and so forth, allowing the organization to focus on the most pressing issues. This enrichment is critical to an informed, proactive security decision-making process.
6. Automation Options: EASM automation will considerably cut down the effort made manually in terms of asset discovery, alerts, and prioritizing vulnerabilities. Automated workflows will also improve response times such that teams are focused on strategic initiatives rather than running repetitiveness. A well-automated EASM tool improves efficiency with minimal human error and by proxy, makes a security program more resilient.

How Can SentinelOne Help with External Attack Surface Management (EASM)?

SentinelOne can greatly enhance EASM by providing world-class visibility into internet-facing assets. It enables organizations to discover and catalog all devices, services, and entry points exposed outwardly through advanced scanning and monitoring capabilities. It integrates with real-time threat intelligence and vulnerability management capabilities. Its EASM feature can instantly identify vulnerabilities in exposed assets, such as unpatched software, open ports, or misconfigured services. Organizations can prioritize and remediate security issues rapidly, drastically reducing the exposure window that might be available to possible external threats.

SentinelOne for EASM provides automated risk remediation and mitigation. If vulnerabilities or potential entry points are identified, remedial actions, such as isolating assets, patching applications, or strengthening firewall rules, are automatically triggered.

SentinelOne continuously monitors external threat environments in real time. Its AI-driven engine analyzes changes, identifies new exposures, and automatically adjusts an organization’s security posture. SentinelOne’s unique Offensive Security Engine stays one step ahead of adversaries and predicts emerging attacks. It gets into their mindset, finds flaws and weaknesses in your existing infrastructure, and sorts them out with Verified Exploit Paths for additional assistance.

SentinelOne is built with interoperability, making it easy to integrate with various security information and event management systems, vulnerability scanners, and IT service management platforms. In-depth analytics and customizable reports show the security posture of the external attack surface, the extent to which vulnerability mitigation has been done, and compliance with security standards.

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Conclusion

EASM is playing a critical role in securing an organization’s internet-facing assets in this increasingly complex digital environment. It ensures they are continuously visible in real-time so that identifying vulnerabilities, prioritizing risks, and proactively responding to attacks by the outside world can be facilitated. This way, security teams can curb potential issues before they can be exploited, making their organizations face the lowest cyber threats.

An efficient EASM program is built from the combination of the right tools, ongoing monitoring, and best practices such as the ongoing asset discovery process and threat intelligence integration. A scalable EASM strategy ensures that it grows well with the organization while also integrating into other security platforms for a unified security posture.

Organizations benefit not only by affording themselves enhanced visibility and control of external risks but also by helping in compliance efforts, shrinking the attack surface, and overall resilience against cyberattacks through the implementation of EASM. As the threats from outside continue to evolve, EASM stands as a proactive defense that should not be avoided by an organization to protect its digital footprint.

FAQs

1. What is EASM?

EASM is an approach to cybersecurity that identifies, evaluates, and addresses risks across an organization’s internet-facing assets and services. It improves overall cybersecurity posture by closely monitoring and managing various attack surfaces.

2. Common External Attack Surfaces to Monitor?

Common external attack surfaces to monitor include websites and web applications, cloud storage services, publicly accessible databases, IoT devices, APIs, VPNs, and exposed network services like SSH or RDP. For phishing and brandjacking, social media presence, domains, and subsidiaries would need to be monitored. Scanning of these assets on a regular basis helps find hidden vulnerabilities and prevents unforeseen exposures.

3. What is the difference between Attack Surface Management and External Attack Surface Management?

ASM covers everything that could go wrong within the organization’s internal and external interfaces. EASM, however, only deals with the management and protection of internet-exposed resources and services. Here, ASM takes an insider look and EASM focuses on external vulnerabilities that are accessible and exploitable by external threats.

4. Why is EASM critical for modern cybersecurity?

EASM is important as today’s attack landscape is majorly focused on the exploitation of external vulnerabilities. The increased usage of cloud services, IoT, and work from anywhere has exponentially increased the attack surface area from external attackers and opened many more entry points for devastating cyber threats. Therefore, identification of vulnerabilities by using EASM can mitigate these risks before any devastating breach takes place on an organization’s reputation, data, or financial assets.

5. What are the main challenges of managing an external attack surface?

The main challenges are the rate at which the external assets grow every day, the complexity of discovering unknown or shadow IT, how fast new unknown vulnerabilities come into existence, and how it is to prioritize remediation activities. For many organizations, the cost management of a holistic EASM solution and its integration into existing security workflows is a very significant hurdle in its adoption.

6. How do EASM tools integrate with existing security workflows?

APIs enable an interface into existing security workflows between SIEM systems, vulnerability scanners, and ITSM platforms. Such integration allows for automated ticketing for vulnerability remediation, enhanced threat intelligence, and unified visibility across all security operations, therefore fortifying the overall cybersecurity ecosystem without disruption of established processes.

7. How can organizations get started with EASM?

To begin with EASM, organizations have to make a list of their internet-facing assets first. Then, implement a strong EASM platform that would offer continuous monitoring, automated vulnerability scanning, and prioritized remediation guidance. Additionally, they have to define clear security policies, conduct recurrent training of the IT and security teams, and make sure of C-level buy-in to create a culture of proactive cybersecurity management.