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🧪 DVWA LABS
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Part of the DVWA Lab Series — 30 Labs
Lab 26 of 30 · 86.7% complete
Authentication is the front door of every web application. Break it and everything behind it is accessible regardless of what other controls exist. I’ve seen applications with excellent SQL injection protection, solid XSS filtering, and proper CSRF tokens — where the login form itself was vulnerable to a one-line SQL injection bypass that got you in as admin with no credentials at all.
Lab 26 covers three distinct authentication bypass attack classes that DVWA demonstrates explicitly: SQL injection in login forms, session ID prediction from DVWA’s Weak Session IDs lab, and cookie manipulation for privilege escalation. Each one is a different failure mode. The SQL injection failure is a query construction problem. The session ID failure is an entropy problem. The cookie manipulation failure is a trust problem — the application trusts values stored client-side without server-side validation.
Work through this lab and you’ll have bypassed DVWA’s login via SQL injection, predicted session IDs from DVWA’s Weak Sessions lab, and manipulated cookie values to confirm the privilege escalation pattern. Then chain them into a single documented attack path.
Which authentication bypass technique have you practised in a lab?
SQL injection login bypass Session token manipulation Forced browsing / direct URL None yet
DVWA Authentication Bypass Lab 26 Objectives
Bypass DVWA login with SQL injection — understand the vulnerable query structure
Analyse DVWA session cookies for entropy and predictability using Burp Sequencer
Exploit DVWA Weak Session IDs across all three security levels
Chain authentication bypass findings into a documented account takeover path
⏱️ Lab 26 · 3 terminal exercises · Burp Suite + DVWA ### ✅ Prerequisites - DVWA SQL injection from Lab 11 — the login bypass uses the same injection concept in an authentication context - Burp Suite session handling from Lab 24 — cookie analysis uses Burp Proxy and Sequencer - Automated scan baseline from Lab 25 — recall which authentication bypass types scanners miss ### 📋 DVWA Authentication Bypass Lab 26 – Contents 1. SQL Injection Login Bypass — Theory and Payload 2. Exercise 1: Bypass DVWA Login via SQL Injection 3. Session ID Analysis — Entropy and Prediction 4. Exercise 2: Exploit DVWA Weak Session IDs 5. Cookie Manipulation and Privilege Escalation 6. Exercise 3: Chain Authentication Bypass Findings ## SQL Injection Login Bypass — Theory and Payload The vulnerable login query structure is predictable: SELECT * FROM users WHERE username='INPUT' AND password='INPUT'. When the application drops user input directly into this query without parameterisation, injecting SQL syntax into the username field changes the query’s logic entirely.
The classic payload is ' OR 1=1--. What this does to the query: the first ' closes the username string. OR 1=1 adds an always-true condition. -- (note the trailing space) comments out everything after it, including the AND password check. The resulting query returns every row in the users table where the username is blank OR 1 equals 1 — which is every row. The application receives a result set, sees a valid user, and logs you in as the first user returned (typically admin).
SQL INJECTION LOGIN BYPASS — PAYLOADS AND QUERY ANALYSISCopy
Original vulnerable query
SELECT * FROM users WHERE username='[INPUT]’ AND password='[INPUT]’
Classic bypass payload (username field)
Username: ‘ OR 1=1–
Password: anything
Resulting query
SELECT * FROM users WHERE username=” OR 1=1– ‘ AND password=’anything’
^^ commented out
What the database sees
SELECT * FROM users WHERE username=” OR 1=1
→ Returns ALL rows (1=1 is always true)
→ Application takes first row → admin
→ Login succeeds as admin with no valid password
Login as specific user (if you know the username)
Username: admin’–
Password: anything
→ Authenticates as admin specifically, bypassing password check
Alternative payload variants (if single-quote is filtered)
” OR “1”=”1 # double quotes
OR 1=1# # MySQL comment alternative
⚡ EXERCISE 1 — KALI TERMINAL (20 MIN)
Bypass DVWA Login with SQL Injection and Analyse the Vulnerable Source
⏱️ 20 minutes · DVWA + Burp Suite
The login bypass is a two-part exercise: confirm the attack works, then read the source code to understand exactly why it’s vulnerable. Both parts are essential — the payload shows you the attack, the source shows you the fix.
Step 1: Set DVWA security to Low
DVWA Security → Low → Submit
Step 2: Intercept the login in Burp Enable Burp Intercept Go to DVWA login: http://DVWA_IP/login.php Enter any username/password → Submit → Burp catches the POST
Step 3: Modify the username parameter In Burp Intercept, change: username=test → username=’ OR 1=1– (include the trailing space after –) password=anything Forward the request
Step 4: Confirm bypass DVWA should now show the dashboard — login succeeded What username is shown in the DVWA interface? (You’re logged in as the first user in the database — admin)
Step 5: Read the vulnerable source code DVWA login form → View Source button (bottom right) Find the SQL query line Identify: where is the user input dropped into the query? Is there any input sanitisation? Is the query parameterised?
Step 6: Test at Medium security DVWA Security → Medium Retry: ‘ OR 1=1– Does it still work? If not, try: ‘ OR ‘1’=’1 What filtering is applied at Medium vs Low?
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