How do we stop hackers?

One way is with Web Application Firewalls (WAFs)!

Web Application Firewalls

i.e. Main leading providers: Imperva, Akamai, Cloudflare

Protection at different OSI Layers

• DNS Level
• HTTP Request Level (i.e string matching)

Can protect against

• SQL Injection
• XSS
• XXE

• etc

• Tuning and stopping false positives is resource intensive

• There are whole careers and vendors dedicated to detecting and blocking attacks.

Buuuutttttttttt!
You can't protect against everything, they need to be constantly improved upon as new exploits are found.