Websites utilizing SQL databases such as Oracle, SQL Server, or MySQL face significant risks from SQL injection attacks. These attacks are often considered even more severe than cross-site scripting (XSS) due to their ability to compromise vast amounts of data at an alarmingly rapid pace, leading to potentially major consequences. In this blog, we will explore SQL injection attack in detail. 

What is SQL Injection (SQLi) and SQL Injection Attack?

If you are quite familiar with the cyber world, then you must have probably heard of “SQL” or “SQL Injections” terms floating around. In simple words, SQL is a database language that stands for Structured Query Language. It was designed for operating database systems like MySQL, Oracle, Microsoft SQL Server, or SQLite. On the other hand, SQL injection is a cyber-attack that targets the database with the help of specific SQL statements that are crafted to trick the system into performing uncalled and undesired tasks. The SQL injection attack changes the code to modify the command.  

A successful SQL injection attack is capable of:

• Modifying, altering, or deleting data from the database
• Reading sensitive and confidential data from the database
• Retrieving the content of a specific file present on the database management system (DBMS)
• Enforcing administrative operations like shutting down the DBMS

Without proper mitigation controls and security measures, the SQL injection attack can leave an application at a huge risk of data compromise. It can impact the data’s confidentiality and integrity as well as the authentication and authorization with respect to the application. It can also empower an adversary to steal confidential information like user credentials, financial information, or trade secrets by misusing the vulnerability existing in an application or program.

Types of SQL Injection Attacks

Attackers can exploit an SQL injection in various ways, each requiring a different level of knowledge—from amateur to expert. Here are some common SQL injection types:

In-band SQL Injection

It is the most common type of SQL injection attack in which the attacker uses the same communication channel for launching attacks and gathering their results. In-band SQL Injection is infamous among SQL injection attacks for its simplicity and efficiency. It has two sub-variant methods:  

1. Error-based SQL Injection: 

A technique in which the attacker determines the vulnerabilities of the system by deliberately causing the database to produce error messages. Later, these error messages are used for returning full query results and revealing all the confidential information from the database. Attackers can also use this technique to identify vulnerabilities in a website or web application and gather additional information to craft malicious queries.

2. Union-based SQL Injection: 

In this technique, the attacker extracts information from the database by expanding the results returned by the original query. But the Union operator is only useful in case the original or new queries have the same number and data type of columns. 

Inferential (Blind) SQL Injection

Blind SQL injections mainly rely on the server’s behavior and response patterns, where the attacker closely observes the indirect clues. For this observation, the attacker sends the server data payloads. Experts call this technique Blind SQL Injection because the attacker doesn’t receive data directly from the website’s database, making it impossible to view the attack details in-band. The Blind SQL injection is classified into two methods:

1. Boolean:

Here, the attacker sends an SQL query to the database that prompts the application to return a result. However, depending on the query, true or false, the result varies, and based on the result, the information modifies or stays the same, that is there in the HTTP response. With its help, the attacker finds out whether the result is true or false in the message generated. 

2. Time-based: 

The attacker sends an SQL query to the database, and the database waits for a few seconds before responding. By observing the period taken by the database to respond, the attacker gets to analyze whether the query is true or false. Thus, without relying on the data from the database, the attacker can determine if the message used has returned true or false.

Out-of-band SQL Injection

The most uncommon approach to attack an SQL server, this technique relies on particular features of the SQL-enabled database.  It involves the submission of a DNS or HTTP query to the SQL server that has an SQL statement.  If successful, the Out-of-band attack can transmit the contents of the database, escalate user privileges, and perform the same actions that other types of SQL injection attacks perform.

The Recent SQL Injection Attack Examples

Hackers have carried out many SQL injection attacks over the past decade, proving that SQL injections are among the most rapidly evolving types of cyber attacks. Between the years 2017 and 2019, SQL injection attacks accounted for 65.1 % of all attacks on software applications. Here is the list of top SQL injection attack examples of all time that every user must be well aware of!

1. In one incident of an SQL injection attack, hackers exploited a vulnerability in the legacy web portal of a British telecommunications company and stole the personal details of 156,959 customers.
    
2. According to HelpNet Security, 60+ government agencies and universities were successfully targeted using SQL injection attack by a hacker who was involved in penetration of the US Election Assistance Commission and subsequent database sale in November 2016.
    
3. The officials at Johns Hopkins University on March 7, 2014, publicly announced that their Biomedical Engineering Servers became victims of an SQL injection attack. The hackers compromised the personal information of 878 students and University staff. They posted a press release and the leaked data on the internet. (source: Wikipedia)
    
4. In May 2020, a New Yorker was charged with hacking into e-commerce websites with the motive to steal credit card information. It was reported that the hacker, along with its gang, used SQL injection techniques to hack into vulnerable e-commerce websites to steal payment card data.

How To Prevent SQL Injection Attacks?

In order to secure your organization and mitigate SQL injection attacks, the developers, system administrators, and database administrators in the organization must follow these below-mentioned steps:

• Ensure to keep all web application software components up to date with the latest security patches and leaving no place for vulnerabilities.

• Avoid using shared database accounts between different applications or websites.

• Regularly monitor SQL statements from database-connected applications.

• Reduce the attack surface by removing any unnecessary database functionality to prevent hackers from misusing it.

• Error messages are key for attackers to learn a great deal about your database architecture, so make sure to display only minimal information.

• Always keep the database credentials encrypted and separate safely.

• Most importantly, these inculcate the practice of periodic VAPT, i.e. vulnerability assessment and penetration testing. A regular VAPT provides a detailed picture of exploitable vulnerabilities existing within an application and all the risks that are associated with these vulnerabilities. It allows IT, security teams, to focus on the process of mitigating critical vulnerabilities. 

Conclusion

SQL injection attacks remain a significant threat to application security, capable of compromising sensitive data and disrupting database operations. Their evolving nature requires organizations to adopt proactive measures to mitigate risks effectively. By keeping systems updated, encrypting credentials, monitoring SQL statements, and conducting regular vulnerability assessments and penetration testing (VAPT), businesses can secure their applications and prevent potential exploits. Implementing strong security practices and maintaining vigilance are essential to protecting IT infrastructures from SQL injection attacks.