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🧪 DVWA LAB SERIES
FREE
Part of the DVWA Lab Series — 30 Labs
Lab 21 of 30 · 70% complete
⚠️ Authorised Lab Environment Only. All SQL injection techniques in this lab must be performed exclusively on your own local DVWA installation or authorised platforms. Testing SQL injection against production applications without written permission violates computer misuse legislation. All exercises target http://localhost/dvwa/ only.
DVWA SQL Injection High Security Lab for 2026 :— Labs 1 through 11 covered SQL injection at Low and Medium security where the injection point was obvious and filters were minimal. High security changes the game: input sanitisation blocks the classic ' payloads, WAF-like filtering removes obvious keywords, and the application’s SQL logic is restructured to reduce direct injection surfaces. This lab teaches the techniques that work when the obvious paths are closed: second-order injection that stores and later executes payloads, blind injection that confirms vulnerabilities through timing and boolean responses when direct output is suppressed, and the cookie-based injection path specific to DVWA High that demonstrates how sanitisation in one code path can miss another.
🎯 What You’ll Master in Lab 21
Understand why mysql_real_escape_string() stops classic injection and what it misses
Exploit DVWA High’s cookie-based injection path that bypasses URL parameter sanitisation
Execute second-order SQL injection — store payload, trigger later retrieval
Apply time-based blind injection to confirm vulnerabilities when output is suppressed
Use sqlmap’s –level and –risk flags to reach high-security injection points
⏱️ 55 min lab · 3 terminal exercises · Localhost DVWA only #### 📋 Prerequisites — Complete Before Lab 21 - Lab 7: DVWA SQL Injection Low/Medium — foundational SQL injection payloads and UNION-based extraction; Lab 21 builds directly on this - Lab 20: DVWA CSRF Advanced — cross-layer vulnerability chaining context; Lab 21’s second-order injection shows the same stored-then-triggered pattern ### 📋 DVWA SQL Injection High Security 2026 1. Why High Security Is Different — What mysql_real_escape_string() Does 2. The Cookie-Based Injection Path in DVWA High 3. Second-Order SQL Injection — Store, Retrieve, Execute 4. Time-Based Blind Injection — Confirm When Output Is Gone 5. Using sqlmap at High Security Level 6. What Properly Fixes SQL Injection — Parameterised Queries ## Why High Security Is Different — What mysql_real_escape_string() Does DVWA Low security concatenates user input directly into the SQL query with no filtering whatsoever. Medium security applies basic filtering but using methods that can be bypassed. High security uses PHP’s mysql_real_escape_string() function to sanitise input before it reaches the query. This function escapes the characters that SQL injection depends on: single quotes, double quotes, backslashes, null bytes, carriage returns, and line feeds. A payload like 1' OR '1'='1 becomes 1\' OR \'1\'=\'1 after escaping — the escaped quotes cannot close the SQL string context, so the injection fails.
For most input paths, mysql_real_escape_string() is effective when used correctly. The DVWA High security implementation has a specific architectural decision that creates an alternative injection path: rather than using the URL parameter directly, the application stores the user ID in a PHP session cookie and reads the SQL query parameter from that cookie. The session storage and retrieval introduces a path where the value is used without consistent sanitisation — this is the bypass specific to DVWA High.
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DVWA SQL Injection — Low vs High Security Code Comparison
LOW SECURITY (vulnerable)
$id = $_GET[‘id’];
$query = “SELECT … WHERE user_id = ‘$id'”;
// $id goes in raw — injectable
HIGH SECURITY (sanitised)
$id = $_COOKIE[‘id’];
$id = mysql_real_escape_string($id);
$query = “SELECT … WHERE user_id = ‘$id'”;
// Read from COOKIE not GET!
High security reads the id from the COOKIE header — direct cookie manipulation in Burp bypasses URL parameter sanitisation
📸 DVWA SQL injection source code comparison between Low and High security. Low security reads directly from the GET parameter with no sanitisation. High security reads from a cookie and applies mysql_real_escape_string(). The important architectural detail: the cookie is set by the form submission, but you can modify the cookie value directly in Burp Suite or browser DevTools before the server reads it — bypassing the sanitisation by manipulating the value at the point where it enters the cookie rather than through the sanitised form input.
The Cookie-Based Injection Path in DVWA High
DVWA High security’s SQL injection page reads the user ID from a PHP session cookie named id. When you submit the form by clicking “Submit”, the value you entered is stored in this cookie, and the page then reads that cookie value to run the SQL query. The sanitisation applies to the form input at submission time. However, between form submission and the SQL query execution, the value passes through the cookie — and if you intercept and modify the cookie directly in Burp Suite before the query runs, you can inject into the cookie value without going through the sanitised form input path.
DVWA HIGH — COOKIE INJECTION VIA BURP SUITECopy
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