No Single Layer Is Enough: The Web Security Stack I Actually Trust

After several years in web security, my biggest takeaway is this: no single layer of defense is enough. If your code isn't thoroughly scanned, you haven't deployed a WAF in production, or you're not keeping a close eye on CDN traffic, any one of those gaps can be exploited. Today I'm laying out the things I've repeatedly validated in real projects—static scanning, dynamic scanning, WAF, and how to defend against DDoS and MJJ attacks.

Static Scanning: Defusing Bombs Before the Code Even Runs

My take on static scanning (static code analysis) is that it has to be baked into the development phase—you can't wait until after launch to catch up. I learned this the hard way once: an internal service went live before anyone ran a scan, and it turned out that SQL injection and cross-site scripting vulnerabilities were embedded right in the business logic. Fixing them took a full week longer than the original development cycle.

The whole advantage of static scanning is that it's early. Before the program even runs, it can comb through the source code line by line and catch the classic vulnerabilities—SQL injection, XSS, and the like—right in the CI pipeline. Lowest cost, highest return.

Dynamic Scanning: Problems You Can Only See at Runtime

But static scanning alone isn't enough. From my hands-on experience, some vulnerabilities only surface once the application is actually running: misconfigured settings, authentication logic that can be bypassed under specific request sequences—none of which static analysis can see.

Dynamic application security testing (DAST) is exactly what fills that gap—it simulates attacker behavior against the application while it's running. I typically run DAST in a staging environment, specifically to catch those cases where the code looks fine on paper but falls apart in practice. Using both types of scanning together gives you complete coverage.

WAF: My Last Line of Defense

A WAF (Web Application Firewall) isn't a nice-to-have in my architecture—it's a must. It monitors all inbound HTTP/HTTPS traffic, identifies and filters out malicious requests. Attacks like SQL injection and XSS are essentially stopped at the WAF layer.

There's also an easily overlooked point: many industry compliance requirements (PCI DSS, for example) explicitly mandate WAF deployment. I've seen clients fail an audit outright because they hadn't deployed a WAF, and the rushed deployment afterward put them in an even more reactive position. My advice: don't wait for an incident, don't wait for an audit—set it up from day one.

DDoS and MJJ: Two Entirely Different Playbooks

I don't need to explain DDoS in detail—massive traffic floods take your service down, and the goal is simply to make you unavailable. My standard response involves three things: real-time traffic monitoring with alerts, multi-layered network-level protection, and elastic infrastructure capable of absorbing sudden traffic spikes. If the budget allows, plugging in a professional DDoS mitigation service (Cloudflare, for instance) saves a lot of headaches. In my experience, the response time and traffic scrubbing capability are genuinely better than trying to handle it all in-house.

MJJ attacks take a different approach—they don't try to take you down; they flood your CDN traffic until your bill explodes. I got burned by this once: CDN traffic suddenly spiked to dozens of times the normal level, and after a long investigation I found someone was making bulk requests for static assets. I made several adjustments afterward: capping bandwidth usage, running periodic CDN traffic monitoring, and optimizing content delivery strategies (adding caching, limiting origin-fetch frequency for hot resources). I also maintain close communication with the CDN provider, and if malicious traffic abuse does occur, I'm not above pursuing legal action.

One Last Thing

Prevention is always cheaper than remediation. Static scanning covers the code, dynamic scanning covers runtime, WAF covers inbound traffic, and DDoS/MJJ monitoring covers the infrastructure—stack all four layers together and you've actually secured your web service. Don't expect any single layer to cover everything, and don't skip any of them.