What is SQL Injection (SQLi) Attack and How to Prevent It

  • By Maria
  • May 20, 2022

SQL injection

Cybersecurity is a significant area of focus in technology, regardless of use and industry. Achieving security in applications and across networks is essential for individuals and businesses alike. New threats and attack types emerge regularly, but preventative and response tactics can keep your networks safe. Training staff and ensuring that everyone is aware of cyberattack trends can also serve as an effective strategy in preventing cyberattacks or minimizing the resulting damage. 

What is SQL Injection?

Structured Query Language (SQL) is a widely used programming language. SQL is commonly used for database programming to manipulate and manage data. SQL was first introduced in the 1970s and has since served as the go-to language for commercial and open source databases. When a programming language is around for a long time, its vulnerabilities can become known to hackers and potentially exploited. An SQL injection is a severe cybersecurity attack that attacks databases using specifically designed trick SQL statements. These statements can trigger actions in the system that hackers create. 

How Does an SQL Injection Work?

SQLI attack

The SQL injection communicates the system's actions that benefit the hackers and hurts its target database. The triggered actions vary from attack to attack, but some everyday SQL injection actions could be: 

  • Successfully bypassing authentication to gain unauthorized access to the database
  • Obtaining secure data by breaching safeguards and stealing it
  • Deleting data sets entirely
  • Changing and corrupting data
  • Running outside code 
  • Gaining root access to the system’s back end 

The types of SQL injections that can occur usually fall into three major categories:

  • Un-sanitized Input Injection
  • Blind SQL Injection
  • Out-of-Band SQL Injection

Hackers will often wait and watch the database they target before deciding on a particular SQL injection type. All of these SQL injection types have the potential to seriously, and sometimes irrevocably, damage the systems they attack. A brief explanation of each SQL injection type: 

Unsanitized Input

This popular SQL injection pushes data that isn’t correctly sanitized for characters that should be escaped and validated to be the correct and expected type. It uses an existing query to pull additional data. 

Blind SQL Injection

This attack type doesn’t reveal data directly from the targeted database but instead closely examines indirect clues from the system’s behavior. A cybercriminal may hone in on the details contained in HTTP responses or blank web pages that may have specific user input. They may also pay attention to how long it takes the database to process user input. This could lead to another SQL injection attack avenue being developed for the attacker. 

Out-of-Band Injection

When a hacker cannot achieve their goal in a single, direct query-response attack, they may explore crafting SQL statements that trigger the database system to create a connection to a separate, external server the cybercriminals control. They can then harvest data or even control the behavior of the database. Sometimes, these types of digital attacks are deferred for a later time and get triggered by an action later on. This is what is called a Second-Order Injection.

SQL Injections – an Example

A prevalent conceptual SQL injection example would be when a valid query is manipulated to retrieve additional data, often sensitive in nature. This data ends up in the hands of cybercriminals if the SQL injection is successful and can be used in unauthorized and fraudulent ways. A real-life example of an SQL injection attack was revealed in 2012 by a hacker group called GhostShell. They targeted financial services organizations, consulting firms, academia, law enforcement, and the CIA via an SQL injection attack and leaked over a million user accounts from 100+ websites. 

How to Prevent an SQL Injection

If you are exploring how to prevent SQL injection, there are several best practices to help avoid falling victim to this type of cyber-attack. SQL injection prevention can be aided by: 

  • Not placing user-provided input directly into SQL statements, but instead using prepared remarks and parameterized queries 
  • Sanitizing user-provided inputs
  • Not leaving sensitive data in plaintext
  • Encrypting all sensitive data that resides in the database
  • Limiting database permissions and privileges by granting only the privileges that users genuinely need to do their work
  • Avoiding sharing database error language directly with the user
  • Using a Web Application Firewall (WAF) for web applications that access databases
  • Keep databases upgraded and up to date with the latest available patches

There is no doubt that SQL injection attacks are common and can be pretty damaging. A lot is known about these attacks, as they have been around for an extended period. This knowledge has provided individuals and organizations with a simple toolkit of strategies to prevent such cyberattacks. By taking necessary precautions, coding carefully, and monitoring databases consistently, you can keep your databases safe.

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