Describe SQL Injection and how you would prevent it.

Explanation:

SQL Injection is a type of security vulnerability that allows an attacker to interfere with the queries that an application makes to its database. It occurs when an attacker is able to insert or "inject" malicious SQL code into an input field, which is then executed by the database server. This can lead to unauthorized access to sensitive data, data manipulation, or even deletion of entire tables.

Key Talking Points:

• Definition: SQL Injection is a code injection technique that exploits a vulnerability in an application's software.
• Cause: Occurs due to improper handling of user input in SQL queries.
• Impact: Can lead to unauthorized database access, data leakage, data manipulation, or destruction.
• Prevention:
  • Use prepared statements and parameterized queries.
  • Employ stored procedures.
  • Validate and sanitize user inputs.
  • Employ least privilege principles for database access.
  • Implement web application firewalls (WAFs).

NOTES:

Reference Table:

Pseudocode:

Here is a simple example using prepared statements in Python with a SQLite database:

   import sqlite3

   # Connect to SQLite database (or create it if it doesn't exist)
   conn = sqlite3.connect('example.db')

   # Create a new SQLite cursor
   cursor = conn.cursor()

   user_id = input("Enter user ID:")
   
   # Using a prepared statement to prevent SQL Injection
   cursor.execute("SELECT * FROM users WHERE id = ?", (user_id,))
   
   # Fetch the results
   result = cursor.fetchall()

   # Print the results
   for row in result:
       print(row)

   # Close the connection
   conn.close()

Follow-Up Questions and Answers:

1. Question: What are some common types of SQL Injection attacks?

   • Answer: Common types include Classic SQL Injection, Blind SQL Injection, and Out-of-Band SQL Injection. Classic SQL Injection directly manipulates queries, Blind SQL Injection relies on indirect evidence (like true/false conditions), and Out-of-Band uses alternative channels for the attack.

2. Question: How can an attacker exploit a Blind SQL Injection vulnerability?

   • Answer: An attacker can exploit Blind SQL Injection by asking the database a series of true or false questions and observing the application's response to infer information about the database schema and its data.

3. Question: Why is input validation important in preventing SQL Injection?

   • Answer: Input validation is crucial because it ensures that only properly formatted data is processed by the application. It acts as the first line of defense by checking input data against defined criteria, reducing the risk of malicious data being processed.

By understanding these concepts and preventive measures, you'll be well-prepared to discuss SQL Injection in an interview setting.