SQL Injection is a type of web application security vulnerability in which an attacker is able to submit a database SQL command which is executed by a web application, exposing the back-end database.
A SQL Injection attack can occur when a web application utilizes user-supplied data without proper validation or encoding as part of a command or query. The specially crafted user data tricks the application into executing unintended commands or changing data. SQL Injection allows an attacker to create, read, update, alter, or delete data stored in the back-end database. In its most common form, a SQL Injection attack gives access to sensitive information such as social security numbers, credit card number or other financial data. SQL Injection is one of the most prevalent types of web application security vulnerability.
Key Concepts of a SQL Injection Attack
SQL injection is a software vulnerability that occurs when data entered by users is sent to the SQL interpreter as a part of an SQL query
Attackers provide specially crafted input data to the SQL interpreter and trick the interpreter to execute unintended commands
Attackers utilize this vulnerability by providing specially crafted input data to the SQL interpreter in such a manner that the interpreter is not able to distinguish between the intended commands and the attacker’s specially crafted data. The interpreter is tricked into executing unintended commands
A SQL Injection attack exploits security vulnerabilities at the database layer. By exploiting the SQL injection flaw, attackers can create, read, modify, or delete sensitive data
Attacks can also be characterized based on the goal, or intent, of the attacker. Therefore, each of the attack type definitions.
Identifying Injectable Parameters: The attacker wants to probe a Web application to discover which parameters and user-input fields are vulnerable.
Performing Database Finger-printing: The attacker wants to discover the type and version of database that a Web application is using. Certain types of databases respond differently to different queries and attacks, and this information can be used to “fingerprint” the database. Knowing the type and version of the database used by a Web application allows an attacker to craft database specific attacks.
Determining Database Schema: To correctly extract data from a database, the attacker often needs to know database schema information, such as table names, column names, and column data types. Attacks with this intent are created to collect or infer this kind of information.
Extracting Data: These types of attacks employ techniques that will extract data values from the database. Depending on the type of the Web application, this information could be sensitive and highly desirable to the attacker.
Adding or Modifying Data: The goal of these attacks is to add or change information in a database.
Performing Denial of Service: These attacks are performed to shut down the database of a Web application, thus denying service to other users. Attacks involving locking or dropping database tables also fall under this category.
Evading Detection: This category refers to certain attack techniques that are employed to avoid auditing and detection by system protection mechanisms.
Bypassing Authentication: The goal of these types of attacks is to allow the attacker to bypass database and application authentication mechanisms. Bypassing such mechanisms could allow the attacker to assume the rights and privileges associated with another application user.
Executing Remote Commands: These types of attacks attempt to execute arbitrary commands on the database. These commands can be stored procedures or functions available to database users.
Performing Privilege Escalation: These attacks take advantage of implementation errors or logical flaws in the database in order to escalate the privileges of the attacker. As opposed to bypassing authentication attacks, these attacks focus on exploiting the database user privileges.
Preventing SQL Injection Vulnerabilities
- SQL injection can be prevented if you adopt an input validation technique in which user input is authenticated against a set of defined rules for length, type, and syntax and also against business rules.
- You should ensure that users with the permission to access the database have the least privileges. Additionally, do not use system administrator accounts like "sa" for Web applications. Also, you should always make sure that a database user is created only for a specific application and this user is not able to access other applications.
- Another method for preventing SQL injection attacks is to remove all stored procedures that are not in use.
- Use strongly typed parameterized query APIs with placeholder substitution markers, even when calling stored procedures.
- Show care when using stored procedures since they are generally safe from injection. However, be careful as they can be injectable (such as via the use of exec() or concatenating arguments within the stored procedure).
Also Read : Hack Website using SQL Injection
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