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Introduction to SQL Injection and Attacks

SQL Injection also is known as SQLi. It is basically a hacking technique which is the current topic of discussion in today’s IT world. It is being mentioned in a number of vulnerability reports today. This blog is written to provide you the complete information of SQLi, its introduction, details and how you can prevent the SQL injection attacks.

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Before diving into the topic it is quite important to know what Is SQL programming language and why is it beneficial?

Introduction to SQL Language

SQL is basically a query language. It consists of queries, clauses, predicates, statements and expressions. In this language statements are used to create tables which have columns and rows. SQL queries are used to retrieve the data from a database with a specific condition. For hacking procedures as well these queries are used. There are a number of commands to query the database which is directly used by SQL. These commands are like Select, Update, Alter or Create and much more are there.

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Most used SQL injection syntax and condition by hackers is “1=1” as the value returned by this statement is true. Hackers always try to use this feature to retrieve data from the database, while semicolons and apostrophes are also an integral part of SQL and are used to hack the data so are a great reason and source of vulnerability.

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A Brief Introduction to SQL Injection

Mostly the hackers exploit the log-in file or fields of the database of mobile and web applications. The un-protected log-in fields are vulnerable, so cannot be protected completely. In modern mobile and web application the data is stored centrally and can be used to render and deliver information and data. Such small but important vulnerabilities exist in almost all e-commerce, financial and social web portals.

SQLi is nothing new but is just a small SQL command which is inserted maliciously into the SQL statements by the hackers through any un-sanitized input field. By injecting these SQLi statements, the hackers can easily and illegally communicate with the database of applications, and can harvest the sensitive information.

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An example of SQLi

In the below-listed example, you can see the SQL injection case where the hacker is using the web page to access the database of a website or web application.

Here in the above example, there is a basic button and a text field. In this search field you can see there are the input C# written by the hacker. Here in this example the search button will search the database for the book, but the hacker can use the input field to access the complete database and for that they will have to use the SQL injections. Even some advanced hackers can access the complete database through this query and can crash the complete database or website.

How will the Hackers do?

Here the hackers will insert “” into the search field and the button may lead to an error page which can even display more information than required. The web application of the above example is not secure and cannot handle the SQL injections properly. By using just a few illegal characters and sniffing around the leads, the hacker can access the complete information like the query statement like “union select password from users”. He can easily harvest the passwords and username from the database through such query.

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This is a common and general way to exploit the database while other methods canalso be used by hackers to exploit the database. A few hackers use the third party tools to extract the data or information from the user's website, such tools are SQL Map and SQL Ninja.

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Damages Caused by SQL Injections   

Through SQL injections the hackers can steal the username and passwords for either criminal or commercial purpose, even they can wipe out the content completely from the website or hack the web page even.  So in short, they can harm the website in the following way:

  • Can silently spy or monitor the website
  • Can corrupt the entire database and delete the backups
  • Can also obtain the admin’s credentials through SQL injections, which can have serious consequences
  • Can take the control of your website remotely and manipulate or exploit the application
  • Can remove or update the server resident application by gaining its unauthorized access through the network.

Making the code Secure and Vulnerable from SQL Injections

The inputs by the users into the web application must be validated. Many programming frameworks also have their own input sanitation methods which should be used whenever any input is given by the user. Additionally, you can take the following steps to make the input secure and to neutralize the SQL injections:

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The validations should be based on the white list so the data should only be accepted through only a specified structure not the bad or rejected patterns. For that you can check for the following patterns:

  • Data Type
  • Size
  • Range
  • Format
  • Expected values

b) Again, you can also take some additional precautions like in place of using string concatenation you can take the following steps:

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  • You should use those database components which are safe like stored procedures, object bindings for commands and parameterized queries
  • Developers can use ORM libraries like Hibernate, iBatis or EntityFramework

c) The access can be restricted in functionality and database objects and for that least privilege should be granted to the user.

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How to Prevent SQL Cheat Sheet Attacks

Though SQL injections are not safe,they can be easily prevented through small steps. If the database software and application commands will be separated or the un-trusted user data will be prevented then the application can be secured. A variety of actionable ways to prevent the application from SQL attack can be:

  • Identify SQL Injection Attack Vectors for the solution of your database application.
  • Develop best practices and protections for SQL query
  • Train the developers for SQL risks and preventions
  • Find problems with the code
  • Find code vulnerabilities
  • Test and Check for SQL injections

Final Words

Today SQL injection is a topic of discussion among developers and the application owners. As the hackers are using new techniques to hack any web application or mobile application data so it has become important to make them secure and the developers are even securing their web application through protection and SQLi prevention techniques.

Read More: How to Restore a Database Backup from SQL?

There are even a number of third-party SQL injection tools available in the market, which the developers use to make their application free from SQLi attack and these tools have built-in capabilities to make the application secure. Still other developers make the application secure by coding. They code the application by using SQL validations or stored procedures to make the application secure. Here the application security is quite more important.

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