Q: A critical vulnerability in a popular Java logging framework (like Log4j) is announced on a Friday night. It allows Remote Code Execution (RCE) via a simple HTTP header. You have 500 microservices. How do you respond systematically?

I would execute a defense-in-depth response:

• Immediate Mitigation (Edge Filtering): I cannot patch 500 services instantly. Immediately deploy a WAF rule (AWS WAF/Cloudflare) globally to block incoming HTTP requests containing the known malicious exploit strings (e.g., ${jndi:ldap...}). This protects the perimeter instantly.
• Identification (Scanning): Run an emergency vulnerability scan across all container registries and codebases using tools like Trivy or Snyk to identify exactly which of the 500 services actually use the vulnerable version of the library.
• Internal Mitigation (Egress Control): The RCE requires the compromised server to make an outbound connection to the attacker's server to download the payload. Ensure strict Egress Network Policies / Security Groups are in place. If a backend service doesn't need the internet, block its outbound traffic.

• Remediation & Rollout (Patching): Work with developer teams to upgrade the library in the identified services, build new images, and deploy them systematically over the weekend.