hardMultiple Choice
CS0-003 Practice Question: During a security assessment, you discover that…
During a security assessment, you discover that an organization's web application is vulnerable to SQL injection because it concatenates user input directly into SQL queries. Which of the following is the BEST remediation strategy?
⚠ Common exam trap
The CS0-004 exam often tests the misconception that input validation or a WAF is sufficient to prevent SQL injection, but the exam expects you to recognize that only parameterized queries/prepared statements address the root cause by enforcing data vs. code separation.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use parameterized queries or prepared statements.
Parameterized queries (prepared statements) separate SQL logic from user data by using placeholders, ensuring that user input is always treated as data, not executable code. This directly prevents SQL injection by eliminating the ability to alter the query structure, regardless of the input content.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Encode all output data.
Why it's wrong here
Encoding output data is a crucial defense against Cross-Site Scripting (XSS) attacks, where malicious scripts are injected into web pages and executed by end-users' browsers. However, it does not prevent SQL injection. SQL injection occurs when an attacker manipulates input to alter the logic of a database query *before* the data is retrieved or processed, making output encoding ineffective as the malicious query has already executed on the backend.
- ✗
Deploy a web application firewall (WAF).
Why it's wrong here
Deploying a Web Application Firewall (WAF) can provide an additional layer of defense by inspecting HTTP traffic and blocking known attack patterns, including some SQL injection attempts. While a WAF acts as a valuable compensating control, it does not eliminate the underlying vulnerability in the application's code that allows for SQL injection. Relying solely on a WAF leaves the application susceptible if the WAF is bypassed or misconfigured, failing to address the fundamental security flaw.
- ✓
Use parameterized queries or prepared statements.
Why this is correct
Parameterized queries, also known as prepared statements, are the most effective defense against SQL injection because they fundamentally separate the SQL code from user-supplied data. The database engine first compiles the query structure, then binds user input as literal data values, ensuring that any special characters in the input are treated as data, not executable SQL commands. This prevents attackers from altering the query's intent by injecting malicious SQL syntax.
- ✗
Implement input validation using a whitelist.
Why it's wrong here
Implementing input validation, especially using a whitelist approach, is a strong security practice that restricts user input to only known-good characters, formats, or values. While it can filter out many malicious inputs and reduce the attack surface, it is not a complete defense against all forms of SQL injection. Complex or highly specific injection techniques might still bypass even robust validation, making it an an important complementary control rather than a standalone solution for preventing SQL injection.
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Related to this question
Learn chapter
Executive Security Reporting
Key term
Remediation
Remediation is the process of fixing or eliminating vulnerabilities, misconfigurations, or security weaknesses in an IT environment.
Key term
SQL injection
SQL injection is a web security vulnerability that allows an attacker to interfere with the queries an application makes to its database, often to read, modify, or destroy data.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CS0-004 practice question is part of Courseiva's free CompTIA certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the CS0-004 exam.