SQL injection is a form of cyberattack in which an attacker manipulates a database with SQL (Structured Query Language) code to gain access to sensitive valuable information. Because it can possibly be used against any online application or website that uses a SQL-based database, it is one of the most common and dangerous types of attacks. Famous examples include attacks on Sony Pictures and Tesla, among others.
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Types of SQL Injection
SQL injections are generally classified into three types: in-band SQLi (Classic), inferential SQLi (Blind), and out-of-band SQLi. SQL injections can be classified based on how they access backend data and how much damage they can cause.
In-Band SQLi
The hacker uses the same line of communication to initiate attacks and collect data. Because of its simplicity and efficiency, in-band SQLi is one of the most commonly used types of SQLi attacks. This method is divided into two sub-variations:
- SQLi based on errors: The hacker performs actions that cause the database to generate error messages. The attacker could possibly use the information provided by these error messages to learn about the database’s structure.
- Union-based SQLi: This technique uses the UNION SQL operator to combine multiple select statements created by the database into a single HTTP response. This reply may contain information that the attacker can use.
Inferential SQLi (Blind)
To gain knowledge more about the server’s configuration, the hacker sends data packets to it and inspects its response and behavior. Because the information is not transmitted from the server database to the hackers, the attacker is unable to see details about the attack in-band.
Blind SQL injections depend on the server’s reaction and behavior tendencies, so they are generally slower to execute but just as dangerous. Blind SQL injections can be divided into two types:
- Boolean: The hacker sends a SQL query to the database, requesting that the application return a result. Based on whether the query is true or false, the outcome will differ. The data in the HTTP response will change or remain unchanged depending on the outcome. The attacker can then determine whether the message produced a true or false result.
- Time-based: The hacker sends a SQL query to the database, which causes the database to wait (for a set number of seconds) before responding. The attacker can determine whether a query is true or false based on the time it takes the database to respond. Based on the outcome, an HTTP response will be generated either immediately or after a short delay. The hacker can thus determine whether the message they used was restored true or false without depending on database data.
Out-of-band SQLi
The hacker can only carry out this type of attack if certain features on the system server used by the web-based application are activated. This type of attack is typically used as a backup to in-band and inferential SQLi techniques.
Out-of-band SQLi is used when the attacker is unable to use the same channel to start the attack and collect information, or when a server is too slow or unsafe to perform these actions. These techniques rely on the server’s ability to generate DNS or HTTP requests in order to transfer data to hackers.
How Does SQL Injection Work?
An SQL query is mainly a request sent to a database—an automated repository of information—for some sort of activity or operation to be performed, such as data querying or SQL code execution. One example is when a user’s login credentials are submitted via a web form to gain access to a site.
This type of web form is commonly built to handle only very particular types of data, such as a user name and/or password. When that information is entered, it is compared to a database, and if it matches, the user is granted access. If they don’t, they won’t be able to enter.
Potential issues arise because most web forms do not have a way to prevent additional details from being entered. Hackers can take advantage of this flaw by using the form’s input boxes to submit their own requests to the database. This could enable them to engage in a variety of illegal deeds, such as accessing sensitive data or manipulating the data in the database for their own purposes.
Prevention Against SQL Injection Attack
Though SQL injection attacks remain the most harmful threat to web admins, the best part is that there are many things website owners can do to reduce the risk. Here are three steps you can take to substantially lower your chances of becoming a victim of a SQL injection attack:
Make Prepared Statements and Parameterization Mandatory
All database queries must be written using prepared statements with generalized queries, also known as variable binding. You can differentiate between user input and code by identifying all SQL code engaged with queries, also known as parameterization.
While dynamic SQL as a coding approach can provide more flexibility in app development, it can also introduce SQLi vulnerabilities as approved code instructions. By using standard SQL, the database will handle malicious SQL statements as data rather than a potential command.
Toughen Your Operating System and Applications
This step goes beyond preventing SQL injection attacks to ensure that your complete physical and virtual framework is functioning properly. With the big news of supply chain glitches in 2020, many people are turning to NIST and other industry-standard protection checklists to harden their operating systems and applications.
Adopting application vendor security guidelines can improve an organization’s defensive posture by assisting in the identification and deactivation of unnecessary applications and servers.
Keep Your Secrets Safe with Encryption
It’s best to assume that internet-connected apps aren’t secure. As a result, password encryption and hashing, private information, and connection strings are essential.
For good reason, encryption is almost universally used as a data protection method today. Sensitive information could be in plain sight for an intruder if appropriate encryption and hashing policies are not in place. While encryption is only one component of the security checklist, Microsoft notes that it “converts the problem of data protection into the problem of securing cryptographic keys.”
