Every day, businesses spin up new digital services (websites, APIs, and cloud instances) and it can be for security teams to keep track. Somewhere in that churn, an unmonitored subdomain or misconfigured bucket lurks, waiting for an opportunistic attacker to slip in.
External Attack Surface Management (EASM) flips the script: instead of reacting to breaches, you map and monitor every internet‑facing asset continuously. Hidden exposures become visible vulnerabilities you can close before they’re weaponized.
How does EASM work?
At its core, EASM is the practice of discovering, inventorying, and assessing every externally accessible digital asset. This includes domains, subdomains, IP addresses, cloud services, IoT devices, third‑party partners, and any other public-facing digital that could be used as an attack route.
Unlike traditional vulnerability scanning, which focuses on known assets within a perimeter, EASM casts a much wider net to discover both knowns and unknowns:
Automated discovery: Uses active scans, passive DNS analysis, certificate transparency logs, and OSINT (Open‑Source Intelligence) to uncover forgotten or shadow assets.
Uses active scans, passive DNS analysis, certificate transparency logs, and OSINT (Open‑Source Intelligence) to uncover forgotten or shadow assets. Continuous monitoring: Tracks changes over time (new subdomains, recently deployed cloud workloads, or exposed development servers) to detect drift from asset inventory.
Tracks changes over time (new subdomains, recently deployed cloud workloads, or exposed development servers) to detect drift from asset inventory. Risk prioritization: Scores exposures based on exploitability and business impact, enabling teams to focus on high‑priority threats first.
The result is a dynamic, always‑up‑to‑date map of what adversaries see, enabling organizations to shore up weak points before they’re exploited.
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