SQL Injections: Understanding the Threat & 10 Ways to Prevent Attacks

SQL Injection is a prevalent cybercrime tactic and is recognized as one of the top 10 critical security threats by OWASP, a leading document on web application vulnerabilities. Failing to protect your website from this attack could put your business and your customers at significant risk. This article explores SQL Injections: what they are, how they operate, their various types, and 10 practical ways to prevent such attacks.

What is a SQL injection?

SQL injection attacks, commonly referred to as SQLi, involve inserting altered SQL queries into input fields on web forms. This technique extracts sensitive information from the database, such as usernames, passwords, credit card details, and other personally identifiable information (PII). In some scenarios, attackers exploit vulnerabilities in a website’s input fields, passing malicious queries to the back-end database through forms designed for user input. In other cases, attackers manipulate cookies to corrupt database queries or inject malicious code by tampering with HTTP headers, especially when the web application does not properly validate or sanitize these inputs.

How Does It Work?

Structured Query Language (SQL) is a programming language that manages data in relational database systems. It allows users to perform various operations, including retrieving, updating, and deleting records. Attackers can exploit vulnerabilities by embedding malicious code into query strings sent to the SQL server. These attacks often target user-input fields, such as forms on web pages or web applications, which can act as entry points if not properly secured. Depending on the application’s vulnerabilities, various techniques are used to carry out such attacks.

SQL injection example

A typical SQL injection example involves a login form.  A website features a login form where users input their username and password. The SQL query running in the background might appear as follows: SQL SELECT * FROM users WHERE username = ‘user’ AND password = ‘password’; An attacker could input malicious code instead of valid credentials, such as: Username: admin’ OR ‘1’=’1 Password: anything The resulting query would become: SQL SELECT * FROM users WHERE username = ‘admin’ OR ‘1’=’1′ AND password = ‘anything’; Since ‘1’=’1′ constantly evaluates to true, the query bypasses authentication, potentially granting the attacker unauthorized access to the system.

Three Common Types of SQL Injection Attacks

1. In-Band SQL Injection

Also known as classic SQL Injection, in-band SQLi is a type of cyberattack in which an attacker injects malicious code into a web application’s input field. The code is then executed by the application’s database, allowing the attacker to retrieve, modify, or delete sensitive data.

This occurs when the attacker can directly retrieve the results of the injected query, making it a relatively easy attack. If not mitigated by proper input validation and secure coding practices, such injections can lead to unauthorized access, data leakage, and compromise of the entire application.

2. Inferential SQL Injection

Also known as Blind SQL Injection or Blind SQLi, inferential SQLi is a more complex attack. Hackers insert harmful SQL code into web application inputs and gauge the success of their attack by observing the application’s behavior or response, rather than directly extracting data.

 This type of attack is difficult to detect and defend against, as the signs of manipulation may not be immediately apparent. It poses a risk of unauthorized data access, and if defences are insufficient, it can compromise the app and its databases.

There are two primary types of inferential SQL injection attacks:

3. Boolean-based Injection: 

This strategy allows attackers to exploit a web application’s input to interact with a database using boolean-based queries. These queries lead to true or false responses, which attackers can use to gather information about the database’s structure and content, potentially extracting sensitive data or gaining unauthorized access.

4. Time-based Injection: 

Using this technique, attackers delay the application’s response time by injecting malicious SQL queries that introduce artificial time delays. Attackers can infer the database structure and extract valuable information by measuring the impact on response times.

As a result, unauthorized data access can occur, allowing attackers to extract sensitive information, gain control of an application, or compromise the underlying database if defences against blind SQLi attacks are inadequate.

5. Out-of-Band SQL Injection

Out-of-band SQL injection (OOB SQLi) is an advanced attack technique in which attackers exploit web application inputs to initiate communications with external systems they control, such as a server under their command. This allows them to extract confidential data or gain control of the targeted system while bypassing conventional in-band communication between the application and its database.

The consequences of data breaches

Cybercriminals highly value SQL injection attacks for their versatility. These attacks can modify or delete sensitive data, steal customer details, or even take complete control of a website. One danger is that SQL injections aren’t always easy to detect. Even when an application properly sanitizes user input to block immediate attacks, the malicious data can be stored locally and cause damage when used in different scenarios later on.

Cybercriminals launching SQL injection attacks primarily aim to access sensitive data. They typically target vulnerable database servers to hijack stored information, most often personally identifiable information (PII), which they can sell on the dark web.

Why is PII so valuable? Consider having access to the personal details of a healthcare provider who electronically bills insurers. This information could be exploited to submit fraudulent claims to insurers or Medicare, potentially yielding millions in profits. On the dark web, such records can be purchased for about $500, representing a massive return on investment.

However, medical records are not the only form of PII cybercriminals seek. Any organization collecting and storing data on local servers is at risk of SQL injection attacks. This includes eCommerce businesses, real estate firms, law offices, and financial institutions. Websites that gather information like addresses, phone numbers, birthdates, and Social Security numbers are desirable targets due to the data’s high value.

How to Safeguard Against SQL Injection Attacks

In certain situations, an attacker can infiltrate your site without detection, and the impact of a second-order SQL injection attack might not be evident until much later. In other cases, you may observe signs like altered posts or comments, the creation of new admin accounts, password changes, or a disconnected CMS. Fortunately, there are proactive measures you can take to prevent SQL injection attacks from happening. Begin by implementing the following steps:

  1. Regularly update your softwa

Every site owner must have security patches that are consistently updated. This means performing updates as soon as they become available. Regular updates for plugins, themes, and CMS core files are essential to prevent attacks and malware from exploiting vulnerabilities.

  1. Choose Plugins Carefully

Plugins can enhance your website’s functionality, such as improving SEO, social media engagement, and more, but they can also be potential targets for attackers. Each plugin adds another possible entry point for malicious actors, so be selective when choosing which ones to install. Remove unused plugins or those that haven’t been updated in over a year, as outdated code can create weak points for attackers.

  1. Add Multiple Layers of Security

Start by assigning SQL database accounts the minimum privileges required for operation. Avoid using duplicate accounts across multiple websites or applications to prevent cross-contamination. Implement comprehensive input validation for all user-provided data, including drop-down menus, to block malicious inputs. Configure error reporting settings to prevent exposing database error messages to client browsers, reducing opportunities for attackers to exploit these vulnerabilities.

  1. Sanitize Input Fields

User-submitted data, such as on contact forms or other input fields, is a common target for cybercriminals seeking unauthorized access to your database. Use input validation functions, like MySQL escape strings, to ensure that malicious data isn’t passed into SQL queries. Sanitizing input fields filters user data to provide only information that meets specific criteria that can be entered. For instance, the input field should only allow numbers, dashes, and parentheses if asking for phone numbers.

  1. Never Trust User Input

Use prepared statements and parameterized queries to secure your database. By defining SQL code within these statements and passing each parameter systematically, you can prevent attackers from altering query intent. Additionally, using stored procedures to create SQL statements with parameters stored in the database adds another layer of protection by minimizing exposure to raw SQL code, making it more difficult for attackers to exploit.

  1. Install a Vulnerability Scanner

Automated vulnerability scanners conduct thorough website scans to identify and patch vulnerabilities before attackers can exploit them. These tools strengthen your site’s defence against SQL injection attacks and other forms of malware, helping to keep it secure.

  1. Use a Web Application Firewall (WAF)

A Web Application Firewall (WAF) is critical for preventing SQL injection attacks by filtering out malicious bots and threats targeting your site. When choosing a WAF, it is beneficial to incorporate the OWASP Top 10 threats, offering more potent protection against these stealthy attacks.

Effective Mitigation Practices

Preventing future attacks is crucial for safeguarding against unauthorized access and data breaches. While measures like input validation, parameterized queries, database protection, and maintaining data integrity are essential, they are insufficient.en choosing a WAF, it is beneficial to incorporate the OWASP Top 10 threats, offering more potent protection against these stealthy attacks.

Train development teams

It is crucial to train development teams on how to address SQL injection vulnerabilities to enhance overall web security. By understanding the risks and adopting secure coding practices, developers can apply adequate safeguards during the design and development phases. This proactive strategy helps prevent security gaps, protects sensitive data, and ensures the development of strong web applications that are resistant to attacks.

Establish an incident response plan

Developing a structured response plan or a quick-reference guide to minimize the effects of potential attacks is essential for ensuring business continuity. The plan should include prompt detection of the attack, isolating impacted systems, and engaging cybersecurity experts to assess the scope of the breach. Clear communication with stakeholders, including customers and regulatory authorities, maintains transparency. Remediation involves fixing vulnerabilities, recovering compromised data, and strengthening security protocols to prevent future incidents. Regularly testing and updating the plan will ensure your team is well-prepared to handle security events efficiently.

Collaborate with cybersecurity specialists

You’re not alone if your business lacks in-house security experts to guard against SQL injection attacks. Site Lock offers comprehensive cyber security solutions tailored to businesses of all sizes, helping protect your site from these threats and other cyber risks. Leverage our services and competitive pricing to ensure cyber criminals can’t exploit vulnerabilities in your system.

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