SQL injection that gets around mysql_real_escape_string()

🦠 SQL Injection: Outsmarting mysql_real_escape_string()

Are you familiar with the term SQL injection? If not, let me bring you up to speed. SQL injection is an attack technique where malicious actors insert malicious SQL code into an application's database query. These attacks can be dangerous as they allow attackers to manipulate, steal, or even delete your valuable data. 😱

You may have heard that using mysql_real_escape_string() function in PHP can safeguard your application from SQL injection attacks. But is it really foolproof? 🤔

Let's explore a sample situation to understand the potential vulnerabilities of mysql_real_escape_string(). In the PHP code below, we're using mysql_real_escape_string() to sanitize user input before constructing an SQL query:

$login = mysql_real_escape_string(GetFromPost('login'));
$password = mysql_real_escape_string(GetFromPost('password'));

$sql = "SELECT * FROM table WHERE login='$login' AND password='$password'";

On the surface, it appears that we're taking the necessary precautions by sanitizing user inputs. However, there are still instances where this code can be hacked, and your application's security is compromised. 😮

When it comes to SQL injection, it's important to consider the different types of attack vectors and how they can be used to bypass mysql_real_escape_string(). It's true that classic injections using patterns like aaa' OR 1=1 -- would not work in this case. But that doesn't mean we're completely safe.

There is always a possibility of attackers exploiting certain edge cases and leveraging creative techniques to outsmart our security measures. In this case, they could potentially bypass mysql_real_escape_string() by utilizing input variations that the function fails to account for. Let's dive into one such example.

Exploiting Input Variations

Consider the following scenario: the website has a multi-language support feature, allowing users to input their login and password in different languages. The code snippet that handles this scenario may look something like this:

$login = mysql_real_escape_string(GetFromPost('login'));
$password = mysql_real_escape_string(GetFromPost('password'));

$sql = "SELECT * FROM table WHERE login='$login' AND password='$password' AND lang='en'";

While we're still using mysql_real_escape_string(), the code assumes that all characters used for login and password will be in English. This assumption leaves room for exploitation.

Let's say an attacker inputs their login and password using a different character set, such as Japanese or Arabic. Since mysql_real_escape_string() only accounts for English characters, it will not properly escape the non-English characters in the query. As a result, an attacker can inject malicious code using non-English characters and bypass our security measures.

For instance, an attacker could input the login as ' OR lang='en' -- in Japanese or Arabic characters. Since our code assumes that the input will be in English and does not properly escape the non-English characters, the attacker can sneak in their malicious SQL code.

Safeguarding Against SQL Injection

Now that we understand the vulnerabilities of mysql_real_escape_string(), how can we protect our applications against SQL injection attacks? Here are a few measures you can take:

1. Prepared Statements: Instead of manually constructing SQL queries, use prepared statements. Prepared statements separate the SQL code from the user input and ensure that inputs are treated as data, minimizing the risk of SQL injection. For example:

$stmt = $conn->prepare("SELECT * FROM table WHERE login=? AND password=?");
$stmt->bind_param("ss", $login, $password);

1. Input Validation: Implement strict input validation techniques to ensure that only expected characters and formats are accepted. Employ regular expressions or other validation methods to sanitize user inputs effectively.

2. Least Privilege Principle: Ensure that your application's database user has limited privileges to mitigate potential damage. Grant them only the necessary permissions for the application to function correctly.

3. Updating Libraries and Frameworks: Keep your programming language, database, and other relevant libraries up to date. Regularly check for security patches or updates to ensure you have the latest security enhancements.

By adopting these best practices, you can significantly reduce the risk of SQL injection attacks and ensure the safety of your application and your users' data.

📣 Call to Action: Let's Secure Your Applications Together!

SQL injection is a real threat, but armed with knowledge and proper safeguards, you can protect your applications and users from falling victim to these attacks. Remember to always validate and sanitize user inputs, use prepared statements, and keep your software up to date.

Have you encountered any SQL injection issues in your applications? Share your experiences and best practices in the comments below! Let's empower each other to build more secure applications that stand up against these relentless attacks. 👊🔒