Insecure Use of SQL Queries

Fixing Insecure Use of SQL Queries

About SQL Injection (SQLi)

What is SQL injection (SQLi)?

SQL injection (SQLi) is a type of security vulnerability that allows attackers to exploit an application's interaction with a SQL database.

This occurs when an application fails to properly sanitize user input and includes untrusted data in an SQL query, allowing attackers to inject malicious code or modify the intended behavior of the query.

SQL injection can affect various types of applications that interact with SQL databases, such as web applications, content management systems, and e-commerce platforms.

Attackers can use various techniques, such as crafted queries or filter values, to inject malicious code or entities into the application.

Check out this video for a high-level explanation:

What is the impact of SQL injections?

SQL injection can lead to various security threats and risks, such as:

• Information disclosure: SQL injection can expose sensitive information, such as user data, login credentials, or other types of confidential information, to unauthorized parties.
• Unauthorized access: SQL injection can allow attackers to gain unauthorized access to databases, perform unauthorized actions, or modify data.
• Denial-of-service: SQL injection can cause denial-of-service (DoS) attacks by injecting malicious queries or values that consume system resources, such as CPU or memory, leading to system crashes or slowdowns.
• Arbitrary code execution: SQL injection can execute arbitrary code on the database server by injecting malicious queries or values that exploit vulnerabilities in the application or the underlying operating system.

SQL injections are very common and have been the cause of many high-profile breaches.

How to prevent SQL injections?

To prevent SQL injection, it is important to follow security best practices and implement appropriate security measures, such as:

• Use parameterized queries: Use parameterized queries and other secure coding practices to ensure that user input is properly sanitized and not used to construct SQL queries directly.
• Use input validation: Validate user input to ensure that it is safe and does not contain malicious code or characters that can be used for injection attacks.
• Limit user access: Limit user access to databases to authorized users and restrict access to sensitive information and actions.
• Use secure coding practices: Follow secure coding practices, such as code reviews, vulnerability scanning and testing, and threat modeling, to ensure that the source code is free of vulnerabilities and that SQL injection vulnerabilities are addressed.
• Use a web application firewall: Use a web application firewall (WAF) that can help prevent SQL injection by filtering and blocking malicious traffic.

References

Taxonomies

• OWASP Top 10 - A03 Injection
• SANS TOP 25 - #3
• CWE-89: Improper Neutralization of Special Elements used in an SQL Command ('SQL Injection')

Explanation & Prevention

• OWASP: SQL Injection Attacks
• OWASP: SQL Injection Prevention Cheat Sheet
• OWASP: Query Parameterization Cheat Sheet
• CAPEC-66: SQL Injection
• NoSQL Injection explanation video
• Holistic Info-Sec: Injection risks
• Holistic Info-Sec: Injection countermeasures

Related CVEs

• CVE Details: CWE-89

Training

• Secure Code Warrior: SQL Injection

Option A: Use Prepared Statements - Mysqli

Solution-specific references:

• ORM
• Mysqli documentation

1. Go through the issues that GuardRails identified in the PR/MR

2. Replace the code that looks like this:

   mysql_query("SELECT * from users where email = '" . $_GET['email'] . "';");

   with:

   // $mysqli instance of mysqli class
   if ($stmt = $mysqli->prepare("SELECT * FROM users WHERE email=?")) {
   
       /* bind parameters for markers */
       $stmt->bind_param("s", $_GET['email']);
   
       /* execute query */
       $stmt->execute();
       [...]
   }

3. Test it

4. Ship it 🚢 and relax 🌴

Option B: Use Prepared Statements - PDO

Solution-specific references:

• ORM
• PDO documentation

1. Go through the issues that GuardRails identified in the PR/MR

2. Replace the code that looks like this:

   mysql_query("SELECT * from users where email = '" . $_GET['email'] . "';");

   with:

   // $pdo instance of PDO class
   $stmt = $pdo->prepare('SELECT * FROM users WHERE email=?');
   $sth->execute($_GET['email']);
   $result = $stmt->fetchAll();

3. Test it

4. Ship it 🚢 and relax 🌴

Option C: Use Prepared Statements - Doctrine ORM

Solution-specific references:

• ORM
• doctrine/orm
• Getting Started with Doctrine

1. Go through the issues that GuardRails identified in the PR/MR

2. Replace the code that looks like this:

   mysql_query("SELECT * from users where email = '" . $_GET['email'] . "';");

   with:

   // $em instance of EntityManager
   $qb = $em->createQueryBuilder();
   $qb->select('u')
    ->from('users', 'u')
    ->where('u.email = ?1')
    ->setParameter(1, $_GET['email']);
   
   $query = $qb->getQuery();
   $result = $query->getResult();

3. Test it

4. Ship it 🚢 and relax 🌴