A public signup form is the front door of your SaaS application. While keeping it open lets legitimate users join, it also leaves your application vulnerable to automated bots and bad actors looking to exploit your infrastructure.
Without proper security controls, an unguarded signup form can quickly turn from an onboarding tool into a major vulnerability.
Why Is a SaaS Signup Form a Major Attack Surface?
A SaaS signup form is a major attack surface because it exposes publicly accessible API endpoints that accept user input and create database records without prior authentication.
Since anyone on the internet can hit your registration endpoint, attackers can use automated scripts to send thousands of HTTP requests per minute. Unlike login forms that require existing credentials, signups allow arbitrary data submission. This makes them ideal targets for bot operators who want to test stolen data, waste system resources, or abuse free tier offerings.
