Glossary
Attack surface management (ASM / EASM)
The continuous discovery and monitoring of an organization's exposed assets, especially those reachable from the internet.
Attack surface management is the practice of continuously discovering, inventorying and assessing the assets an attacker could target. External attack surface management (EASM) focuses on internet-facing assets, using sources such as DNS records, certificate transparency logs, IP address registrations and internet-wide scan data to find domains, hosts and services that belong to the organization — including those nobody remembered to register.
Its main value to vulnerability management is finding the unknown: forgotten test environments, legacy marketing sites, shadow IT and infrastructure inherited through acquisitions. These assets are often unpatched precisely because they are missing from the inventory and scanning scope.
In a VOC, ASM feeds the asset inventory and sets exposure attributes used for prioritization. See asset inventory for vulnerability management.