EASM, CAASM, shadow IT: the vocabulary for a problem that's simple to state and hard to solve — truly mapping everything an attacker can see of your organization, including what you forgot about.
The continuous discovery, monitoring, and securing of everything an attacker could target — on-premises infrastructure, cloud workloads, SaaS applications, internet-facing assets, third-party connections, and "shadow IT". The core idea: you can't protect what you don't know exists.
Discovery deliberately done "from the outside in": you start from a plain domain name, with no access or prior knowledge — exactly an actual attacker's vantage point — then expand the map through DNS records, certificates, IP ranges. The goal: a living inventory of everything reachable from the internet, including what internal teams don't even know they own.
Our automated recon (SunuRecon-OSINT)The opposite approach, "from the inside": aggregating data already sitting in existing tools (EDR, cloud, directories) via their APIs into one unified view of known assets — ownership, configuration, software version. A mature program uses both: EASM finds what you didn't know you had, CAASM organizes what you already know you have.
EASM is unauthenticated and deliberately adversarial — it only sees what a real attacker would see, with no privileged access. CAASM has legitimate access to internal tools and aggregates their data. Asking "could an attacker see this without being invited to?" tells you which one answers your current need.
Systems exposed on the internet but never actively patched, monitored, or even known to the security team — often deployed by a business team outside official processes (a forgotten test server, an abandoned marketing subdomain). These are statistically the easiest targets, precisely because nobody is watching them.
The external surface is everything reachable from the internet with no prior access — websites, APIs, connected devices, cloud services. The internal surface is what an attacker can reach once already inside the network (lateral movement). Both matter, but the external one is almost always the initial entry point.
Every new cloud service, every SaaS app adopted by a team, every connected vendor, every remote employee adds a potential entry point. The attack surface is never static — it keeps expanding, often faster than security teams can map it manually — which is why continuous, automated discovery matters more than a one-off exercise.
Inventory continuously (not once a year), disable or isolate what's no longer in use, require strong authentication on everything exposed, and treat every new service or subdomain as something to monitor from the moment it's created rather than a discovery made after the fact.
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