Inherited App Engine application: you want to check for insecure binaries and XSS vulnerabilities. Which service do you use?

Cloud Security Scanner is the correct choice because it's a web vulnerability scanner designed specifically for App Engine applications. It automatically scans your application for common vulnerabilities like Cross-Site Scripting (XSS), insecure binaries, mixed content, and outdated libraries. Cloud Armor is a WAF (Web Application Firewall) that protects against DDoS and common web attacks, but it doesn't scan for application-level vulnerabilities. Stackdriver Debugger helps you inspect the state of a running application to diagnose issues, not scan for security flaws. Stackdriver Error Reporting aggregates and analyzes errors in your application, which is useful for operational health but not security scanning.