The answer is that the application executes system commands and returns output, which is one of the two common indicators of a command injection vulnerability. This is correct because command injection fundamentally relies on an application passing unsanitized user input directly to a system shell, allowing an attacker to inject shell metacharacters such as semicolons, double ampersands, or pipes to chain arbitrary commands. When the application then echoes back the results of those commands—for example, displaying the output of a `whoami` or `ls` call—it confirms the vulnerability is exploitable. On the Certified Ethical Hacker CEH exam, this concept tests your ability to recognize injection points in web applications and APIs, often appearing in questions about input validation flaws or OWASP Top 10 risks. A common trap is confusing command injection with SQL injection, but remember that command injection targets the operating system shell, not a database. For a quick memory tip, think of the mnemonic “S.O.S.” — Shell metacharacters, Output returned, System call executed — to spot the three telltale signs.
CEH Web Application and Injection Attacks Practice Question
This CEH practice question tests your understanding of web application and injection attacks. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Which TWO of the following are common indicators of a command injection vulnerability? (Select 2)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The application allows input of shell metacharacters like ;, &&, or |
Command injection typically involves injecting shell metacharacters (;, &&, |) and can be confirmed by observing time delays with sleep commands.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
The application allows input of shell metacharacters like ;, &&, or |
Why this is correct
These metacharacters can be used to chain commands.
Related concept
Read the scenario before looking for a memorised answer.
✗
The application reflects user input in the page without encoding
Why it's wrong here
That indicates XSS.
✗
The application returns database error messages
Why it's wrong here
Database errors indicate SQL injection, not command injection.
✗
The application uses parameterized queries for database access
Why it's wrong here
Parameterized queries prevent SQL injection, not command injection.
✓
The application executes system commands and returns output
Why this is correct
Direct execution of commands is a clear indicator.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Trap categories for this question
Command / output trap
Database errors indicate SQL injection, not command injection.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the CEH exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CEH question in full detail.
Identify which CEH exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Web Application and Injection Attacks — This question tests Web Application and Injection Attacks — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The application allows input of shell metacharacters like ;, &&, or | — Command injection typically involves injecting shell metacharacters (;, &&, |) and can be confirmed by observing time delays with sleep commands.
What should I do if I get this CEH question wrong?
Identify which CEH exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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