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What is SQLi?

What is SQLi?

SQL injection (SQLi) is a cyberattack that threatens web applications and databases. It involves injecting malicious SQL code into an application, allowing attackers to view, modify, or even delete data within a database. 


Understanding a SQL injection attack

To execute an SQL injection attack, malicious users exploit vulnerabilities in web applications that interact with databases. SQL, or Structured Query Language, is a programming language specifically designed for managing data in relational database management systems. Attackers insert malicious SQL code into strings passed to a SQL server, tricking the server into executing unintended commands.


Consequences of SQLi

The impact of a successful SQL injection attack can be severe and can have various negative consequences for an organization: 

  • Exposes sensitive company data: SQL injection attacks can enable attackers to retrieve and alter data, potentially exposing sensitive company information stored on the SQL server.
  • Compromises users' privacy: When SQL injection attacks target databases containing user information, such as credit card numbers, attackers can expose private user data, posing a risk to individuals' privacy.
  • Provides attackers administrative access: If a database user has administrative privileges, an attacker can gain unauthorized access to the system using malicious SQL code. 
  • Compromises the integrity of your data: SQL injection attacks can lead to unauthorized changes or deletions of data within the system, compromising the integrity and reliability of the information.


Types of SQL injection attacks

To effectively protect against SQL injection attacks, it is necessary to understand the different types of techniques employed by attackers. SQL injection attacks can be categorized into three main types: 


In-band SQL injection

In-band SQL injection is the most common type of attack. It involves the attacker using the same communication channel for the attack and to gather results. 


Error-based SQL injection

Error-based SQL injection uses SQL commands to generate error messages from the database server. By examining these error messages, attackers can gain insights into the database structure, which can later be exploited. 


Union-based SQL injection

Union-based SQL injection uses the UNION SQL operator to combine multiple select statements and return a single HTTP response. Attackers can leverage this technique to extract information from the database.

Read also: Common cyberattack vectors 


Best practices

To minimize the risk of SQL injection vulnerabilities, consider implementing the following security measures:

  • Install the latest software and security patches: Stay updated with the latest software versions and security patches vendors provide. These updates often include security fixes that address known vulnerabilities.
  • Grant minimal privileges to SQL database accounts: Only provide SQL database accounts with the minimum privileges necessary to perform their intended tasks. 
  • Configure error reporting: Instead of sending detailed error messages to the client web browser, configure error reporting to capture and log errors on the server side. 
  • Avoid shared accounts and limit database error exposure: Avoid using shared accounts to mitigate the potential impact of a compromised account. 

See also: HIPAA Compliant Email: The Definitive Guide  

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