SQL injection sometimes referred to as SQLI, is a popular attack method that uses malicious SQL code to manipulate backend databases and access data that was not meant to be shown.
What may an attacker do if a SQL injection attack is successful?
A successful attack may result in unauthorized access to user lists, deletion of whole tables, and, in certain situations, the attacker acquiring administrator rights to a database, all of which are extremely damaging to a corporation.
How and Why Do SQL Injection Attacks Happen?
- An attacker must first locate weak user inputs inside the web page or web application to launch a SQL Injection attack. A web page or web application with SQL Injection vulnerability directly utilizes such user input in a SQL query.
- The attacker can generate input material. This type of material is sometimes referred to as a malicious payload and is a critical component of the assault. Upon the attacker’s transmission of this material, malicious SQL statements are executed in the database.
What Is It?
See Exploiting SQL Injection: a Hands-on Demonstration to understand how a SQL Injection attack is carried out step by step and what significant implications it may have.
Example of a Basic SQL Injection
The first illustration is quite basic. It demonstrates how an attacker may get past application security and authenticate as the administrator by using SQL Injection vulnerability.
On a web server, the following script is pseudocode. It is a straightforward illustration of a username and password authentication. The user’s table in the sample database includes the columns username and password.
- # Create POST variables
- Name is a request.
- Request = POST[‘username’] passed.
- # SQLi SQL statement SQL = “SELECT id FROM users WHERE username='” + name + “‘ AND password='” + password + “‘”
- # Run the database SQL query.
Union-Based SQL Injection Example
The UNION operator is used in one of the most prevalent varieties of SQL Injection. It enables the attacker to create a single result from the output of two or more SELECT operations. It is known as union-based SQL Injection.
This method is demonstrated in the following. It makes advantage of the deliberately insecure website testphp.vulnweb.com, which Acunetix hosts.
SQL injection types
The SQL injection attack comes in several forms. The main types to be aware of are listed below:
The simplest and most prevalent type of SQL injection attack is in-band SQL injection. Hackers assemble the data they require to create a query from error messages. The attack and data collection can both be carried out by the hacker using the same communication channel.
Error-based SQL injection – This technique uses error messages to gather details about the database’s structure. Making error messages general is vital to prevent them from giving hackers too much information, such as table names and contents.
While utilizing this variant, the hacker is oblivious to the web application’s or page’s vulnerability.
Example of a blind SQL injection
When a hacker cannot “see” flaws in the system, such as when error notifications are blocked, they attempt to trigger conditional responses that will allow them to piece the puzzle together. This is done through blind SQL injection techniques.
Hackers could search for minute variations in the HTTP responses generated by tracking cookies when running SQL queries against the system doesn’t give any results. Even when data is hidden, this determines whether the query returns data. They are referred to as conditional reactions. Advanced hackers utilize a process of elimination to decode data character by character once they’ve located where it is to factor in the potential cost of an SQLi should personal information such as phone numbers be included.
What are SQL statements?
SQL is a standardized language used to access databases and change them to provide user-customizable data representations. These duties are carried out by various SQL elements, such as queries that retrieve data using the SELECT statement and user-supplied parameters.
A typical SQL database query for an eStore would resemble the following:
SEARCH FOR ITEM NUMBER, ITEM NAME, AND ITEM DETAIL FROM THE ITEM
A string query is created from this by the web application and delivered to the database as a single SQL statement:
& Request.QueryString & sql query= “SELECT ItemName, ItemDescription FROM Item WHERE ItemNumber = ” (“ItemID”)
The following SQL query can then be produced from a user-provided input at http://www.estore.com/items/items.asp?itemid=999:
Choose the item’s name and description from the item where the item number is 999.