01
DNS names the obvious ones.
Mail and sender records, verification tokens, CNAMEs and the sign-in realm show who runs a client’s mail, identity, hosting and software. All of it public.
02
Job ads and case studies name the rest.
“Experience with our payroll platform required.” A vendor’s case study that names your client as a customer. Each supplier goes to your client to confirm, with where we found it.
03
Ranked by blast radius.
How much damage a failure there would do. Catastrophic: the identity provider, and an endpoint agent that updates itself on every laptop. Severe: processors of regulated data. High: hosting. Moderate: peripheral software.
04
Seen across every client you manage.
Say you look after 40 clients. 14 of them use the same payroll provider, and 31 the same identity provider. No spreadsheet shows you that.
05
When a supplier is breached, you know within hours.
The payroll provider files a breach notice. All 14 clients are flagged in one view, with the evidence, within 6 hours. You raise it with all of them the same morning.