What is external attack surface management?

    External Attack Surface Management (EASM) is a cybersecurity methodology that involves the continuous detection, analysis, prioritization, and remediation of vulnerabilities across an organization’s external attack surface. External Attack Surface Management is critical to how modern organizations maintain cyber hygiene and strengthen their security posture. 

    Understanding external attack surface management

    The term “external attack surface” refers to the sum of an organization’s digital assets and all of the possible attack vectors associated with them. Depending on the nature of an organization, this can include a wide range of assets, such as web applications, operating systems, cloud services, APIs, and IoT devices, among others. 

    Essential elements in managing your external attack surface

    External attack surface management is a multi-faceted that comprises several core elements:

    • Asset discovery: To effectively manage the external attack surface, organizations must first identify all internet-facing assets to determine where potential attack vectors might exist.
    • Asset Inventory: Once all relevant assets have been identified, they are systematically cataloged so that they can be effectively assessed and managed on an ongoing basis.
    • Risk scoring: Internet-facing assets are assessed to identify potential attack vectors and are assigned a risk score based on the impact of a potential breach. This allows organizations to prioritize remediation activities to minimize business risk.
    • Remediation: Once vulnerabilities have been identified and prioritized, they are systemically remediated through patches and updates to improve cyber resilience
    • Continuous monitoring: After remediation, assets are continuously monitored and scanned so that emerging attack vectors can be detected and remediated as early as possible.

    The need for external attack surface management

    Through external attack surface management, organizations continuously monitor and assess their digital assets and map their external attack surface. This enables them to identify attack vectors and swiftly remediate them before real attacks can take place. As such, external attack surface management empowers organizations to be proactive in mitigating risk.

    Case studies

    Research from Verizon indicates that 83% of breaches involve external actors, further highlighting the need for external attack management. To date, there have been many high-profile cases of attacks that could have been prevented through external attack surface management. One well-known example is the WannaCry ransomware attack of 2017. 

    The WannaCry attack was a global attack in which hackers exploited the EternalBlue vulnerability in the Microsoft Windows OS, encrypting files on devices and demanding ransom payments in Bitcoin. The attack hit approximately 230,000 computers globally, including Telefónica, a leading Spanish telecommunications company. Had the principles of external attack surface management been applied, the exploited vulnerability in the operating system could have been identified and patched, enabling Telefónica and other victims to avoid having their systems breached.

    Minimizing the exploitable attack surface with external attack surface management

    In contemporary cybersecurity, external attack surface management is a vital component of a strong cybersecurity strategy. As organizations’ digital estates continuously evolve and expand, the number of potential attack vectors simultaneously increases, so mitigating risk from internet-facing assets is critical. Through external attack surface management, organizations can continuously detect, catalog, prioritize, and remediate attack vectors to enhance their security posture and minimize risk.

    Glossary related terms
    Automated Penetration Testing Automated Security Breach and Attack Simulation (BAS) Ransomware Readiness Assessment Red Teaming Security Control Validation Security Validation Vulnerability Management