SQL injection is a set of techniques used by hackers to attack database information using flaws in integrated applications. These techniques can be used to extract and exploit critical user data in databases. Once hackers gain a foothold in this manner, they can easily access, modify, or even delete the data that is important to an organization. This may include things like login credentials, credit card information, and personal data. 

SQL attacks can have serious consequences for an organization, as they could lead to financial and reputational losses. It has become important to spread awareness among employees to keep a check on the links and queries they see while accessing critical records. 

SQL injection attacks, at their core, consist of hackers “injecting” SQL code into a web application through an already accessible web form.  The purpose of this code can have any of the following effects (for example purposes, we are considering a simple login page that checks for a username/password in the SQL database and then returns data associated with that specific username): 
 

1. Direct data extraction: These attacks modify the application’s SQL query to return more data than designed.   
   Example:  Hacker adds a statement to the login form to have the query return all tables in the database.  They can then create customized attack code to pull data from specific tables using the same web form 

2. Error-based attacks: These attacks take advantage of the error messages the database generates in response to improper SQL queries to extract data from the database.   
   Example:  Hacker injects code that modifies the SQL query so that the login checks for “username”, “password”, and “idontexist”.  Since the field “idontexist” doesn’t exist, the SQL query returns an error that can reveal the name of the table being checked.  This information can then be used in other attack methods to dive deeper. 

3. Blind SQL injection: In this form of attack, the attacker does not get any feedback from the database. To determine if a given query was successful or not, they can use timing delays.   
   Example:  Hacker injects code that has a simple “IF” statement that checks the SQL version, and if the version matches, it waits 15 seconds before continuing.  The hacker can then repeat the injection, changing the version the code checks for, and just review the time taken for each attempt to see which one succeeded. 

4. Stored Procedure: This kind of attack is not designed to extract data, but rather to create havok by disrupting normal activity.  This can be done by launching standard SQL commands (also called stored procedures): 
   Examples: 

1. Hacker injects code that runs the “shutdown” command as part of the web query.  This causes the database to go offline and require a manual restart. 

2. Hacker injects code that runs a “DROP” command.  This causes SQL to remove data from the database entirely, and recovery will involve restoration from backup. 
    

It is important to take proactive measures to prevent these attacks from happening. 

Some best practices include: 
 

1. Use parameterized queries: Instead of using plain text queries, isolate the SQL query from the form by using prepared statements or stored procedures to make sure that input values are treated as data and not as executable code. 

2. Validate and sanitize input data: Before accepting input from users, make sure that it conforms to expected values and sanitize the data by removing or encoding special characters that could be used to inject malicious code. 

3. Implement access controls: Limit the privileges of the web application user to the access required to perform the intended actions. This can prevent attackers from using SQL injection to perform unauthorized actions or stored procedures. 

4. Keep software up-to-date: Stay current with security patches and updates for your database software, web applications, and operating system to prevent known vulnerabilities from being exploited. 

5. Use web application firewalls: Implement a web application firewall (WAF) to monitor incoming traffic and block attacks, such as SQL injection, cross-site scripting (XSS), and other known attacks. 

By following these tips, you can reduce the risk of SQL attacks and protect your database and web applications from unauthorized access and data breaches. 

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