The external attack surface is the sum of all potential attack vectors originating outside your internal network, that is, your third-party attack surface. With reliance on third-party vendor relationships increasing, External Attack Surface Management (EASM) plays a more prominent role in data breach prevention programs.
https://www.upguard.com/product/breachsight>Difference Between Attack Surface Management and External Attack Surface Management External Attack Surface Management is a sub-process of Attack Surface Management (ASM) - the ongoing effort of discovering and remediating security risks mapping from IT assets in an organization’s attack surface. External Attack Surface Management solely focuses on vulnerabilities originating outside of your IT ecosystems, such as: Third-Party Cloud Services Supply chain risks External digital assets https://www.upguard.com/blog/best-attack-surface-management-software-solutions address the entire scope of an organization’s attack surface - on-premise and external internet-facing assets, offering EASM in this one ASM solution.