The Ultimate Guide to External Attack Surface Management (EASM)

What is an External Attack Surface?

Your external attack surface encompasses all the digital assets your organization exposes to the public internet. This includes known assets like your main website and web applications, but more importantly, it includes unknown assets.

Shadow IT, forgotten staging environments, abandoned subdomains, and exposed cloud storage buckets all contribute to a bloated and dangerous external attack surface.

Why EASM is Critical Today

Traditional security focuses on the perimeter you know about. External Attack Surface Management (EASM) is the continuous process of discovering, monitoring, and evaluating the security of all internet-facing assets, especially those you don't know about.

Attackers don't attack the heavily fortified front door. They look for the forgotten side window.

Key Components of EASM:

1. Discovery: Continuously scanning the internet to map your organization's digital footprint.
2. Inventory: Cataloging assets, IPs, domains, and certificates.
3. Classification: Understanding the business context of each exposed asset.
4. Vulnerability Monitoring: Identifying weak points, expired certificates, and open ports on those assets.

How to Manage Your Attack Surface

To effectively manage your attack surface, you must adopt an attacker's mindset. Automated tools are essential here. A platform like Exarlo continuously enumerates subdomains, maps exposed services, and flags shadow IT before an attacker can exploit it.