External Attack Surface Management (EASM) is the ongoing process of discovering, inventorying and monitoring all of an organisation’s externally facing assets: domains, subdomains, cloud services, third-party integrations, developer environments, exposed APIs, and more; so you can spot unexpected exposures before attackers do.
Why bother? Because attackers scan the internet for insecure, forgotten, or misconfigured assets. If you don’t know what’s exposed, you can’t protect it! EASM gives you visibility of these assets and the control to turning unknown risks into manageable items on your security roadmap. Attack Surface Management (ASM) platforms and tools help organisations to automate the discovery and monitoring of their attack surface.
What is an External Attack Surface?
An external attack surface is essentially a business or organisation’s internet-facing assets. This can include their websites, APIs, cloud services, VPNs, and any other services that are exposed to the public internet. These are considered part of an “attack surface” because it is an entry-point for attackers to target and attempt to exploit vulnerabilities with an aim to gain unauthorised access to systems, data, or networks.
As an example, a financial services company may have an external attack surface that includes their main website, a customer portal, an API for third-party integrations, and a cloud-based data storage service.
Each of these assets represents a potential entry-point for attackers, and it is important for the company to understand and manage their external attack surface to reduce the risk of a successful cyberattack.
Why Attack Surface Management is Important
Determined attackers are not limited to targeting the most obvious assets, like your company website or customer portal. They will actively search for any publicly accessible assets for weaknesses to exploit.
Without enhanced visibility, you may not know that these assets exist or may have forgotten about them, leaving you vulnerable to attack.
By implementing an external attack surface management (EASM) programme, organisations can:
- Maintain an up-to-date inventory of all internet-facing assets
- Identify and assess vulnerabilities in these assets
- Prioritise remediation based on risk and asset impact
- Continuously monitor for new exposures or changes
- Reduce the risk of data breaches and cyberattacks
A Practical Approach to External Attack Surface Management
A successful EASM programme utilises a combination of skilled analysis, automated tools, and strong operational processes. Here are the key steps to implement an effective EASM strategy:
Discovery
Monitoring
Prioritise
Remediation
Integrate
Continuous Improvement
What does an attack surface management tool do?
An attack surface management tool automates the discovery, monitoring, and management of an organisation’s external attack surface. It provides a view of all internet-facing assets. Key features should include:
- Attack Surface Map: An interactive visualisation of the external attack surface , showing relationships between assets, services, and vulnerabilities.
- Asset Discovery: Automatically discover and inventory all external assets, including domains, subdomains, IP addresses, and cloud services.
- Vulnerability Scanning: Identify known vulnerabilities in external assets, such as outdated software, misconfigurations, and security weaknesses.
- Risk Assessment: Evaluate the risk associated with each asset based on its criticality, exposure, and potential impact on the organisation.
- Continuous Monitoring: Continuously monitor for changes in the external attack surface, such as new assets, modifications, or vulnerabilities.
- Reporting and Analytics: Provide detailed reports and analytics on the external attack surface, including asset inventory, vulnerability status, and risk scores.
- Integration: Integrate with other security tools , such as vulnerability management , incident response, and risk management platforms, to provide an overall view of the organisation’s security posture.
Sign up to the Attack Surface Center to get an interactive view of your attack surface using automated discovery, integrate with vulnerability and risk management.Get Started with Attack Surface Management
Common Challenges in attack surface management
Despite the benefits of EASM, organisations often face challenges in implementing and maintaining an effective attack surface management programme. Some common challenges include:
- Treating EASM as a one-time audit rather than an ongoing process
- Lack of visibility into all internet-facing assets, especially in complex or cloud environments
- Failing to integrate EASM into other security processes like remediation management
- Overlooking risks from developer environments
Measuring the success and the effectiveness of EASM
There are a number of key performance indicators (KPIs) that can be used to measure the success and effectiveness of an EASM programme. Many of these can be subjective, but some common KPIs include:
- Decrease in the number of publicly exposed services
- Reduced risk score for internet-facing assets
- Fewer vulnerabilities discovered in external assets
- Faster response times to new exposures or vulnerabilities
EASM in context: Beyond Vulnerability Scanning
Vulnerability scanning is a central component of EASM, allowing organisations to identify known security vulnerabilities in their external assets. However, EASM goes beyond just scanning for vulnerabilities - it allows the discovery of systems, services, and other assets that may have gone under the radar.
Together, along with operational processes like risk management, these capabilities can strengthen an existing defence-in-depth strategy.
A modern approach to managing your external attack surface
External attack surface management is a modern buzzword, but it isn’t a new concept. Hardening your external attack surface is as crucial today as it was 10 years ago, if not more so.
As organisations continue to expand into more complex environments, especially with the rise of cloud services, the need to standardise and automate the processes of discovery, monitoring, and management of external assets has never been greater.
Our EASM solution provides a collaborative platform for managing your external attack surface by seamlessly integrating the features you need to discover and monitor your assets, assess and remediate vulnerabilities, and manage the identified risks.
