Detailed Technical Analysis of "SQL POST Search Injection on bWAPP"

Overview:
In this write-up, the author explores an SQL Injection vulnerability found in the bWAPP (buggy web application) platform. A structured methodology is described to identify, exploit, and understand the SQL Injection flaw through a practical example involving a SQL search function.

Key Technical Details:

1. Environment Setup:
   bWAPP, a deliberately vulnerable web application, provides an environment for testing security concepts. The author uses a local bWAPP instance installed on XAMPP to demonstrate the SQL Injection vulnerability.

2. Identifying the Vulnerability:
   The author focuses on a search functionality within the bWAPP application (search.php) that takes user input via a POST request. This user input is not sanitized properly before being included in a SQL query, leading to an injection point.

3. Understanding the Injection Point:
   The vulnerability occurs because the user-supplied input is directly concatenated into an SQL query without proper sanitization or parameterization. For instance:

php $sql = "SELECT * FROM movies WHERE title LIKE '%$search%'";

In this case, if an attacker supplies an input such as %' OR '1'='1, the resulting query becomes:

sql SELECT * FROM movies WHERE title LIKE '%%' OR '1'='1'

This transformed query will always be true, potentially exposing all rows in the movies table.

1. Exploiting the Vulnerability:
   The author methodically tests several payloads to demonstrate exploitation. Key payload examples include:

2. Simple Injection: sql %' OR '1'='1 This payload will expand to a query that always evaluates true, causing the database to return all entries.

3. Extracting Database Information: The author escalates the attack using payloads designed to extract information about the database, such as the current user or database version: sql %' UNION SELECT 1,2,database() -- This payload attempts to union the initial result set with specific database information (current database name).

4. Mitigation Strategies:
   To defend against such SQL Injection vulnerabilities, the author suggests the following countermeasures:

5. Parameterized Queries: By using prepared statements and parameterized queries, user input is safely handled: php $stmt = $pdo->prepare("SELECT * FROM movies WHERE title LIKE ?"); $stmt->execute(['%'.$search.'%']);
6. Input Validation: Validating and escaping user inputs ensures that inputs conform to expected patterns.
7. Using ORM/Frameworks: Object-Relational Mapping (ORM) tools and modern web frameworks typically incorporate protections against these types of vulnerabilities.
8. Database Permissions: Restrict database user permissions to minimize the impact of a successful injection.

Key Takeaways:

• Direct Concatenation Vulnerability: The vulnerability arises from directly concatenating user inputs into SQL queries without sanitization.
• Union-based SQL Injection: Using UNION in SQL Injection can help an attacker retrieve additional database information beyond the intended query results.
• Prepared Statements: Employing prepared statements is one of the most robust defenses against SQL Injection as they separate code from data.
• Holistic Input Handling: Proper input validation, escaping, and using higher-level abstractions (e.g., ORM) enhance security significantly.

Conclusion:

The write-up serves as a practical guide for understanding and exploiting SQL Injection in a controlled environment using bWAPP. It underscores the importance of input sanitization and the adoption of secure coding practices to mitigate SQL Injection risks.

For an in-depth demonstration, review the original post on Medium here.