What is a SQL injection (SQLi) attack and how can you prevent them?

How secure is your system? You may have locked the front door, but did you leave the back window unlatched? You could have provided bad actors with the perfect opportunity to conduct SQL injection – all without knowing.

If left unaddressed, this unguarded attack vector can cause an extensive list of devastating consequences.

No matter how small, a gap in your security system may allow attackers to manipulate database queries, gain unauthorized access to sensitive data, and disrupt your entire organization.

That’s why implementing robust security measures and minimizing the risk of SQL injection attacks is essential. This guide will cover everything you need to know, including:

• What is a SQL injection (SQLi) attack and how do they work?
• A brief history of SQL injections
• Different types of SQL injections
• Why do SQL injection attacks exist?
• What is the business impact of a SQLi attack?
• A real-life example of a SQLi attack
• How to detect SQL injection vulnerabilities
• How to respond to SQL injection attacks
• How to prevent SQL injection attacks
• Final thoughts

What is a SQL injection (SQLi) attack and how do they work?

A SQL injection attack is a type of cybersecurity vulnerability that targets web applications by interacting with databases. It occurs when an attacker exploits improper handling of user input within a web application’s SQL queries, allowing them to manipulate the application’s database or access sensitive information.

Wondering how it works? Let’s break it down.

When a web application dynamically generates SQL queries by concatenating user-supplied data without proper validation or sanitization, it creates an opening for SQL injection attacks. Bad actors can exploit this vulnerability by inputting specially crafted strings.

These strings contain malicious SQL commands through the application’s input fields or parameters. If the application fails to adequately validate or sanitize the input, the malicious SQL commands seamlessly integrate with the legitimate query.

Once successful, the consequences can be severe.

Attackers gain the power to execute arbitrary SQL commands, bypass authentication mechanisms, extract or modify sensitive data, and even take control over the entire database server.

This may lead to unauthorized access to accounts, exposure of Personally Identifiable Information (PII), financial losses, website defacement, and reputational damage.

A brief history of SQL injections

The origins of SQL injection can be traced back to the late 1990s when web applications started to rely heavily on databases for data storage and retrieval. As websites began accepting user input without proper validation and sanitization, hackers discovered that they could exploit this vulnerability by inserting malicious SQL statements into input fields. 

By doing so, attackers could bypass authentication, extract sensitive data, modify, or delete database records, and even execute arbitrary commands on the underlying server.

Over the years, SQL injection attacks have remained prevalent and damaging, leading to significant data breaches and financial losses for organizations worldwide.

The continuous evolution of web technologies, the increasing complexity of web applications, and the adoption of different database management systems have kept SQL injection attacks relevant. 

Different types of SQL injections

SQL injection attacks can take on various forms, each exploiting different vulnerabilities within web applications. Here are some of the most common types of SQL injection attacks:

Classic SQL injection

This is the most basic type of SQL injection attack and it occurs when an attacker injects malicious SQL code into a vulnerable application by manipulating user input. The injected code alters the intended behavior of the SQL query, enabling the attacker to perform unauthorized operations on the database.

Blind SQL injection

An attacker leverages the application’s response to determine if the injected SQL code is executing successfully. By carefully constructing queries that generate true or false responses, the attacker can extract information or gain control over the database even without seeing the query results.

Error-based SQL injection

Error-based attacks exploit error messages and responses generated by the database to extract information. By injecting malicious SQL code that triggers an error, the attacker can obtain details about the database structure, table names, or specific data.

Union-based SQL injection

Union-based attacks take advantage of the UNION operator in SQL to combine the result sets of multiple SELECT statements. By injecting a crafted UNION statement, the attacker can retrieve data from other database tables or extract additional information not intended to be exposed.

Time-based SQL injection

Time-based attacks exploit the delay or timing differences in the database’s response to determine if the injected SQL code is executing. By injecting time-delayed SQL statements, the attacker can extract information or manipulate the database by observing the time it takes for the application to respond.

Second-order SQL injection 

A type of vulnerability in web applications where user-supplied data is stored in a database and the malicious SQL code is executed later when the stored data is used in a different context. This can occur when the application fails to properly sanitize or validate the stored data. 

Why do SQL injection attacks exist?

SQL injection attacks exist due to various factors and vulnerabilities present in web applications. Here are some key reasons why SQL injection attacks continue to be a prevalent threat:

• Insufficient input validation: developers fail to validate and sanitize user input which allows bad actors to manipulate queries and inject malicious code. 
• Legacy code and poor security practices: outdated applications may lack robust security measures like parameterized queries.  
• Complexity of web applications: complex architectures increase the chances of overlooking vulnerabilities and failing to implement proper security measures.
• Lack of security awareness: insufficient training and awareness among developers can result in the unintentional introduction of vulnerabilities. 
• Persistence and profitability for attackers: successful SQL injection attacks provide access to valuable data, making them a lucrative endeavor for cybercriminals. 
• Rapidly evolving techniques: attackers adapt and develop sophisticated methods to bypass defenses.  

What is the business impact of a SQLi attack?

A SQL injection attack can have a severe impact on your organization. Here are some of the key consequences:

Data breach

SQLi attacks can result in unauthorized access to sensitive data stored in databases. This can include PII of clients, financial records, intellectual property, trade secrets, or confidential business information.

A data breach can lead to legal liabilities, regulatory penalties, loss of client trust, and damage to the organization’s reputation.

Financial losses

SQLi attacks can cause direct financial losses resulting from stolen financial information, fraudulent transactions, or ransom demands from attackers.

They can also cause indirect losses, which arise from the costs associated with Digital Forensics and Incident Response investigations, legal actions, data recovery, and implementing enhanced security measures.

Reputational damage

An attack can tarnish an organization’s reputation, erode client trust, and impact its brand image. The disclosure of a data breach or compromise can lead to negative media coverage, public scrutiny, and loss of existing and potential clients. Plus, rebuilding trust can be a long and challenging process.

Legal and compliance issues

Organizations are often subject to various legal and regulatory obligations regarding data protection and privacy. Data breaches can lead to legal and compliance issues, including violation of data protection laws, breach notification requirements, and potential lawsuits from affected individuals or regulatory bodies.

Operational disruptions: 

SQLi attacks can disrupt business operations, leading to system downtime, unavailability of services, or compromised functionality. This can impact employee productivity, client experience, and overall business continuity.

Organizations may incur additional costs for incident response, system restoration, and implementing security measures to prevent future attacks.

Competitive disadvantage 

A SQLi attack can give competitors an advantage by damaging the targeted organization’s reputation, client trust, and brand value. Clients may choose to switch to competitors they perceive as more secure and trustworthy.

The loss of market share and decreased client loyalty can also have long-term consequences for the organization’s competitiveness and growth.

A real-life example of a SQLi attack

In 2015, hackers known as “The Impact Team” exploited a SQL injection vulnerability on Ashley Madison – a dating website that focused on facilitating extramarital affairs. By injecting malicious SQL code through input fields, they gained unauthorized access to the database and released the personal information of millions of users.

The breach had significant consequences, causing emotional distress, damaged relationships, and even instances of extortion.

The incident garnered widespread media attention and created a massive reputational crisis for Ashley Madison, resulting in a loss of trust and severe financial repercussions. 

The Ashley Madison breach serves as a prominent example of how SQL injection attacks can have far-reaching consequences. Although the company suffered financial losses and legal implications, the attack also took a personal and emotional toll on clients. 

How to detect SQL injection vulnerabilities

Detecting SQL injection vulnerabilities requires a combination of manual code review and automated security testing. Here are some methods and techniques to help detect SQL injection vulnerabilities:

Code review

• Conduct a manual review of the application’s source code. 
• Look for places where user input is concatenated directly into SQL queries without proper validation or sanitization. 
• Pay attention to functions or methods that construct dynamic SQL queries using user-supplied data.

Input validation and sanitization 

• Check if the application performs thorough input validation and sanitization of user-supplied data. 
• Look for proper usage of input validation techniques such as whitelisting, blacklisting, and regular expressions.

Parameterized queries or prepared statements 

• Review the code to see if it uses parameterized queries or prepared statements instead of dynamically concatenating user input into SQL statements. 
• Parameterized queries separate the SQL code from user input, preventing direct execution of injected SQL code.

Web application security testing 

• Utilize specialized and automated web application security testing tools. 
• These tools send various input payloads and analyze the responses to identify potential SQL injection points. 
• Examples include OWASP ZAP, Burp Suite, and Nessus.

Error messages and exception handling 

• Examine the application’s error messages and exception handling. 
• Error messages that reveal database-related information or display SQL queries can indicate potential vulnerabilities.

Boundary testing

• Perform boundary testing by providing input values that exceed the expected length or range.

Web Application Firewall (WAF) and security audits 

• Deploy a WAF to help detect and mitigate SQL injection attacks. 
• WAFs can monitor and filter incoming requests, blocking potential SQL injection attempts. 
• Periodic security audits and penetration testing can also help identify SQL injection vulnerabilities.

How to respond to SQL injection attacks

In the face of a SQL injection attack, acting swiftly and efficiently is of the essence. Here are key steps to take to mitigate damage and prevent further exploitation.

1. Identify and confirm the attack: detect and confirm SQL injection attacks through log analysis, system monitoring, and identifying suspicious behavior, including abnormal queries, error messages, and unexpected data access patterns.
2. Contain and isolate: immediately isolate the affected system or application from the network to prevent further damage and limit the attacker’s access. 
3. Preserve evidence: document and preserve evidence like logs, server images, network traffic, and database backups.
4. Engage security experts: involve cybersecurity experts, incident response teams, or forensic analysts to assess the extent of the attack, identify vulnerabilities, and provide guidance on remediation.
5. Patch vulnerabilities: identify and patch the vulnerabilities that allowed the attack to occur. This may involve updating software, fixing code flaws, or applying security patches to eliminate exploited vulnerabilities.
6. Remediate compromised data: assess the impact of the attack and determine if sensitive data has been compromised. If so, follow appropriate data breach notification procedures.
7. Improve security measures: strengthen security measures to prevent future attacks, such as implementing secure coding practices, input validation, and parameterized queries.
8. Monitor and review: establish monitoring mechanisms and implement Intrusion Detection Systems (IDS) or Intrusion Prevention Systems (IPS).
9. Learn and improve: conduct a post-incident review to analyze the root causes of the attack and identify areas for improvement.

How to prevent SQL injection attacks

Preventing SQL injection attacks is all about outsmarting intruders before they have the chance to breach your defenses. Here’s what you should consider: 

1. Input validation and sanitization: validate and sanitize user-supplied data before using it in SQL queries to prevent direct SQL injection. Use server-side validation, parameterized queries, or prepared statements.
2. Parameterized queries or prepared statements: bind user input as parameters and eliminate the need for string concatenation to prevent SQL injection attacks. It is also possible to layer these first two methods – first perform input validation on the general user input and then use parameterized queries or prepared statements.
3. Principle of least privilege: apply the principle of least privilege when configuring database user permissions and avoid using privileged accounts for routine operations.
4. Secure coding practices: educate developers on input validation, parameterized queries, and proper handling of user-supplied data. Encourage adherence to secure coding guidelines and conduct regular code reviews.
5. Web Application Firewalls (WAFs): employ WAFs to detect and block suspicious or malicious traffic, including attempts at SQL injections.
6. Regular security updates and patching: stay up to date with security updates for web servers, frameworks, and database management systems to address known vulnerabilities.
7. Security testing and code review: conduct regular security testing, vulnerability assessments, and code reviews to identify and fix SQL injection vulnerabilities.
8. Security awareness training: train personnel on secure coding practices and common attack vectors or risks.
9. Database security configuration: implement secure practices like strong passwords, disabling unnecessary features, restricting access, and implementing appropriate database security controls and auditing mechanisms.
10. Regular monitoring and logging: establish comprehensive monitoring and logging systems to track, analyze, and detect suspicious application behavior, database activities, or user inputs.

Final thoughts

Understanding what a SQLi attack is and how it can affect your bottom line is crucial if you hope to enhance your security posture and safeguard your reputation. It is much easier to prevent the consequences of an attack than to recover from them. 

By prioritizing security at every stage and continuously staying vigilant, you can protect your applications and databases from the damaging effects of SQL injection attacks. And, most importantly, ensure the confidentiality, integrity, and availability of your data.

Cyber attacks are a constant threat, which is why you should partner with a cybersecurity firm that offers persistent vigilance. CovertSwarm will help you identify potential breach points in your organization’s security before they materialize into significant threats. And they’ll do so incessantly. 

To find out more about our Swarm, what we do, and how we can help your business, get in touch today.