EASM

What is External Attack Surface Management?

EASM, or External Attack Surface Management, is a category of security tooling that discovers and monitors everything your organization exposes to the internet. Your external attack surface includes every asset that an attacker could find and potentially target: domains, subdomains, IP addresses, cloud services, APIs, web applications, exposed databases, email servers, and anything else that's publicly reachable.

What makes External Attack Surface Management different from an internal asset inventory is perspective. EASM works from the outside in, mimicking what an attacker would see when they start reconnaissance on your organization. It doesn't require agents installed on your servers or access to your cloud accounts. It discovers assets the same way an attacker would: through DNS enumeration, certificate transparency logs, WHOIS records, port scanning, and web crawling.

EASM tools typically discover:

• Domains and subdomains, including forgotten ones still pointing to active services
• Cloud resources exposed to the internet (S3 buckets, Azure blobs, GCP storage)
• APIs and web applications, including staging or development environments accidentally left public
• SSL/TLS certificates that are expired, misconfigured, or about to expire
• Exposed credentials and secrets that have leaked to public repositories or paste sites
• Shadow IT, meaning services and infrastructure that teams spun up outside of official processes

Why External Attack Surface Management matters for startups

Your external attack surface is almost certainly larger than you think. According to CyCognito, organizations typically have 30% to 50% more internet-facing assets than they're aware of. For startups that move fast and iterate constantly, that gap is often even wider.

Here's why EASM deserves attention early:

1. You can't secure what you don't know exists. Every forgotten subdomain, orphaned staging environment, or test API running on a developer's cloud instance is an entry point you're not monitoring. EASM finds these assets before an attacker does.
2. Shadow IT is a startup reality. Startups don't usually have procurement processes or strict infrastructure governance. Developers spin up services to test ideas, marketing launches a microsite on a separate hosting provider, and nobody remembers to decommission anything. EASM provides continuous visibility into what's actually out there.
3. Attackers start with reconnaissance. Before attempting to exploit a vulnerability, attackers map their target's external surface. They look for the weakest point of entry, which is usually the asset nobody is watching. Running your own EASM means seeing your organization through the attacker's eyes and closing gaps proactively.
4. Compliance and due diligence. SOC 2 and ISO 27001 both expect you to maintain an accurate inventory of your assets and monitor for unauthorized changes. EASM automates that inventory for your external-facing infrastructure and provides evidence that you're actively managing your exposure.

How Fencer helps with EASM

External Attack Surface Management is one of Fencer's core capabilities. Fencer continuously discovers and monitors your internet-facing assets, then correlates what it finds with your internal security data from code scanning and cloud configuration monitoring.

What makes Fencer's approach different:

• EASM plus internal context. Most standalone EASM tools tell you what's exposed. Fencer tells you what's exposed and cross-references it with your code vulnerabilities and cloud misconfigurations. An exposed subdomain running a service with a known code vulnerability and a misconfigured security group is a different priority than an exposed subdomain hosting a static marketing page.
• Continuous, not periodic. Fencer's EASM runs continuously, not quarterly. Your attack surface changes every time someone deploys code, modifies DNS, or spins up a new cloud resource. Continuous monitoring means new exposures are flagged in near-real-time.
• Actionable, not just informational. Fencer doesn't just hand you a list of exposed assets and wish you luck. Findings are prioritized by actual risk, mapped to compliance controls, and linked to the specific remediation steps needed.