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5 SQL Injection Test Methods and Why to Automate Your Testing

May 12, 2022
Oliver Moradov

What Is SQL Injection Testing?

SQL injection tests insert data into your application to verify that you can run user-controlled SQL queries on your database. A test successfully finds a SQL injection vulnerability when a certain user input, which could be used for a malicious input, is accepted by the application without proper validation. 

SQL injection testing is critical to protect web applications that rely on databases. Successful exploitation of SQL injection vulnerabilities could allow unauthorized users to access and manipulate data in the database, and in some cases, compromise the web application and server.

In this article:

5 SQL Injection Testing Methods

SQL injection testing requires understanding an application’s interaction with a database server to access data. Applications often communicate with a database to authenticate web forms (checking credentials against the database) and perform searches (user-submitted input can extract data from the database via SQL queries). Testers must list the input fields with values that could end up in an SQL query. 

Usually, the first test involves adding a quotation mark or semicolon to a parameter or field. If the application doesn’t filter the input, the value in quotation marks could produce a flawed query, while the semicolon could produce an error. 

Testers can also use SQL keywords (e.g., AND, OR) and comment delimiters like — and /* */ to try modifying a query. They can insert a string in the place of a number to generate an error. The testers should monitor all web server responses and inspect the source code. The responses may contain an error without presenting it to the user. Proper error messages offer invaluable information, allowing testers to recreate an injection attack successfully. 

Unfortunately, applications do not always provide the full details of an error, issuing simple 500 errors. In these cases, testers must use blind SQL injection methods. Testers should check every field individually to identify the vulnerable parameters.

Here are some of the testing methods to help identify SQL vulnerabilities:

1. Stacked Query Testing

In the stacked query method, testers complete an SQL statement and write a new one. Testers and developers should ensure that their applications do not support stacked queries (where possible). For example, developers should avoid using a multi-query statement that enables stacked queries.

2. Error-Based Injection Testing

Error-based injection exploits the SQL error messages displayed to users. Users attempt something that likely causes an error and retrieve data from the error message produced. Users with access to information like the names of tables can more easily compromise the underlying database.

To prevent error-based injection attacks, teams must ensure the application never displays internal SQL errors to the user. The application should handle errors internally. 

Related content: Read our guide to error based SQL injection

3. Boolean-Based Injection Testing

The boolean method involves appending conditions to conditional statements (true in some cases, false in others). Attackers can perform several conditional queries to learn about the database. Testers can use this attack method to identify boolean-based injection vulnerabilities.

To prevent boolean-based injection attacks, teams must ensure the application never runs user input as SQL code. One way to achieve this is with prepared statements that ensure SQL does not interpret user input as code. 

Related content: Read our guide to SQL injection payloads

4. Out-of-Band (Blind) Exploit Testing

Out-of-band exploit tests are useful for assessing blind SQL injection vulnerabilities, where the attacker doesn’t know anything about the operation’s outcome. This method uses Database Management System (DBMS) functions to perform out-of-band connections and deliver query results to the attacker’s server.

Related content: Read our guide to blind SQL injection

5. Time Delay Exploit Testing

Time delay exploits are useful for blind SQL injection situations. This method involves sending injected queries and monitoring the server’s response time (if the conditional is true). A delayed response indicates that the conditional query’s result is true.

SQL Injection Testing: Manual vs Automated Testing

Before an organization can secure its applications or websites, it is essential to know about any SQL injection vulnerabilities they contain. SQL injection is a popular attack technique that often impacts businesses severely. Testing teams should test application code for SQL injection vulnerabilities regularly.

Organizations should ideally test their code upon each update. Frequent testing allows security and development teams to identify and address issues introduced in code changes. Testers can look for SQL injection vulnerabilities using manual or automated methods, leveraging scanning tools to accelerate the process. 

Manual SQL injection testing involves manually applying user-supplied inputs to various fields to assess the application or website’s input validation. It is often a time-consuming method, especially when testing many fields. Manual techniques may be inadequate to test everything thoroughly. Given the sheer scale of the task, testers can easily overlook some vulnerabilities. 

Organizations often use automated scanning tools to identify SQL injection vulnerabilities, allowing developers to address coding issues. Web security scanning tools offer a fast, comprehensive testing technique, returning detailed results about any vulnerabilities they discover. Testers can more easily identify affected parameters and URLs, saving time and enabling frequent software updates.

Automated SQL Injection Testing with Bright Security

Bright Security’s Dynamic Application Security Testing (DAST) helps automate the detection and remediation of many vulnerabilities including SQLi, early in the development process, across web applications and APIs. 

By shifting DAST scans left, and integrating them into the SDLC, developers and application security professionals can detect vulnerabilities early, and remediate them before they appear in production. NeuraLegion completes scans in minutes and achieves zero false positives, by automatically validating every vulnerability. This allows developers to adopt the solution and use it throughout the development lifecycle. 

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