What is a SQL Injection?
SQL Injection (SQLi) is a kind of an injection attack that makes it possible to execute malicious SQL statements. These statements control a database server behind a web application. Attackers can utilize SQL Injection vulnerabilities to bypass application safety measures. They can circumvent validation and approval of a site page or web application and retrieve the content of the whole SQL database. They can likewise utilize SQL Injection to add, change, and erase records in the database.
A SQL Injection vulnerability may affect any site or web application that utilizes a SQL database, for example, MySQL, Oracle, SQL Server, or others. Attackers may utilize it to gain unauthorized access to your delicate information: client data, individual information, exchange privileged insights, protected data, and the more. SQL Injection attacks are one of the most seasoned, generally predominant, and most hazardous web application vulnerabilities. The OWASP organization (Open Web Application Security Project) lists injections in their OWASP Top 10 archive as the main danger to web application security.
Types of SQL Injection
- In-band SQL injection (Classic SQL injection): In this method, the attacker utilizes same method to hack the database and get the information from database i.e. result from the database.
- Error based SQL injection: In this type, the attacker gets the error pattern of the database and access it. We can say this one is sort of in-band SQL infusion.
- Union based SQL injection: This method is likewise a part of in-band SQL infusion. In this method, the user combines the query and get the outcome back as some part HTTP reaction.
- Inferential SQL injection (Blind SQL injection): As the name proposes, here attacker doesn’t utilize the band to get information from the database. Attacker has the capability to change the structure of the database by watching patterns of the database. This is a very dangerous sort of SQL injection. This attack takes longer time to execute. Attacker can’t see the output of attack by this strategy.
- Boolean-based (content-based) Blind SQL injection: This is a piece of Inferential SQL injection. In this strategy attacker forces to the database to bring result dependent on true or false condition. Depending on this condition result of HTTP response gets changed. This sort of attack to gather if the payload utilized returned true or false, despite the fact that no information from the database is returned back. These particularly slows the attack.
- Time based Blind SQL injection: This method is additionally the piece of Inferential SQL injection. This strategy is utilized by attackers to put the payloads. In these method attacker offering time to the database to execute the inquiry. Meantime attacker gets an idea regarding the output whether it is true or false. This attack is likewise slow in nature.
- Out-of-band SQL injection: This is a feature based assault. This isn’t very common. This attack is utilized by a attacker when attacker needs to utilize various channels to attack and others to get the result. Out-of-band SQL injection procedures are reliant on the database server’s capacity to make DNS or HTTP requests to deliver data to the attacker.
How to test for SQL injection vulnerabilities
SQLi attacks are simple and have since a long time been automated. Tools like SQLninja, SQLmap, and Havij make it simple to test your own web applications, yet in addition make it simple for hackers.
Automated testing tools can keep you a step in front of hackers searching for a simple payday. Pentesting your web applications with a device like SQLmap is a quick method to check whether your mitigations are satisfactory. SQLmap supports essentially every significant database being used today and can recognize and exploit most known SQL infusion vulnerabilities.
How to Prevent against SQL Injection Attacks
An organization can adopt the following policy to protect itself against SQL Injection attacks.
- User input must always be sanitized before it is used in dynamic SQL statements.
- Stored procedures can encapsulate the SQL statements and treat all input as parameters.
- Prepared statements to work by creating the SQL statement first then treating all submitted user data as parameters. This has no effect on the syntax of the SQL statement.
- Regular expressions can be used to detect potential harmful code and remove it before executing the SQL statements.
- Only necessary access rights should be given to accounts used to connect to the database. This can help reduce what the SQL statements can perform on the server.
- Error messages should not reveal sensitive information and where exactly an error occurred.