Anatomy of a Web Application Scan | HackTool Blog

Running a web scanner feels like a black box: you enter a URL, wait, and get results. Here is what actually happens inside, stage by stage.

Stage 1: Discovery

Before testing anything, the scanner needs to map the target. This starts with DNS resolution, then moves to port scanning and service identification. We check which ports are open, what services are running, and whether the target uses a CDN or WAF.

HackTool's tech fingerprinting module identifies the web server, framework, CMS, and JavaScript libraries in use. This matters because it determines which vulnerability tests are relevant — there is no point testing for PHP deserialization on a Node.js app.

Stage 2: Crawling

The scanner follows links, submits forms, and observes JavaScript to build a map of the application. This includes static paths from HTML, dynamic routes discovered by observing client-side navigation, and API endpoints found in JavaScript source.

Modern SPAs make this harder since much of the application lives behind JavaScript rendering. HackTool handles this by analyzing JavaScript bundles and extracting route definitions and API calls.

Stage 3: Fuzzing and Payload Testing

This is where the real testing happens. For each discovered endpoint and parameter, the scanner sends crafted inputs designed to trigger vulnerabilities:

SQL injection payloads that test for error-based, blind, and time-based injection

XSS payloads across reflected, stored, and DOM-based contexts

SSRF payloads that attempt to reach internal services

Path traversal sequences targeting local file inclusion

Template injection strings for SSTI detection

Each module runs independently and uses its own payload set. The scanner tracks responses, looking for evidence of successful exploitation: error messages, response time changes, reflected content, or behavioral differences.

Stage 4: Analysis

Raw results go through validation to reduce false positives. The scanner compares baseline responses against payload responses, checks whether reflected content is actually exploitable, and correlates findings across endpoints.

Stage 5: Reporting

Results are organized by severity, grouped by vulnerability type, and presented with the actual request/response evidence. You can verify every finding by replaying the exact request that triggered it.

Understanding these stages helps you interpret scan results and know when to dig deeper with manual testing.