The best remediation is to replace the shell call with a safe library function and strictly allowlist approved host values. This directly addresses command injection, where an attacker exploits a user-controlled parameter passed to a shell command like `ping` to execute arbitrary system commands. By using a safe library function—such as `InetAddress.isReachable()` in Java or a dedicated ICMP library—you eliminate the shell interpreter entirely, removing the injection vector. The strict allowlist then ensures only pre-approved internal host values are accepted, preventing any unexpected input from reaching the function. On the Security+ SY-701 exam, this scenario tests your understanding of input validation and secure coding practices, often appearing as a multiple-choice question where the trap is choosing input sanitization alone, which is insufficient against shell metacharacters. Remember the mnemonic: “Kill the shell, allow the well”—remove the shell command and allowlist only trusted values for the most robust defense.
SY0-701 Threats, Vulnerabilities, and Mitigations Practice Question
This SY0-701 practice question tests your understanding of threats, vulnerabilities, and mitigations. 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.
Exhibit
Application log excerpt:
15:08:02 POST /tools/pingHost host=10.0.0.15
15:08:02 Application executed: /bin/sh -c "ping -c 1 10.0.0.15"
15:09:11 POST /tools/pingHost host=10.0.0.15;curl%20http://198.51.100.55/s
15:09:11 Application executed: /bin/sh -c "ping -c 1 10.0.0.15;curl http://198.51.100.55/s"
15:09:12 Outbound HTTPS session established to 198.51.100.55
Based on the exhibit, what is the BEST remediation for the application flaw shown?
A user-controlled parameter is being passed to a shell command on the server. The application is intended to test connectivity to approved internal hosts only.
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "best"
Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Application log excerpt:
15:08:02 POST /tools/pingHost host=10.0.0.15
15:08:02 Application executed: /bin/sh -c "ping -c 1 10.0.0.15"
15:09:11 POST /tools/pingHost host=10.0.0.15;curl%20http://198.51.100.55/s
15:09:11 Application executed: /bin/sh -c "ping -c 1 10.0.0.15;curl http://198.51.100.55/s"
15:09:12 Outbound HTTPS session established to 198.51.100.55
A
Keep the current shell command, but add HTML encoding to the response page.
Why wrong: Output encoding helps prevent browser-side issues, but it does not stop command injection on the server.
B
Replace the shell call with a safe library function and strictly allowlist approved host values.
The flaw is server-side command injection caused by passing user input into a shell. A safe library call removes shell interpretation, and an allowlist limits inputs to known-good targets.
C
Increase the web server timeout so the ping utility has more time to complete.
Why wrong: Timeout tuning does not prevent an attacker from appending extra shell commands to the request.
D
Require users to authenticate before they can access the page.
Why wrong: Authentication may reduce exposure, but it does not correct the underlying unsafe command execution.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Replace the shell call with a safe library function and strictly allowlist approved host values.
Option B is correct because the application flaw is command injection: a user-controlled parameter is passed directly to a shell command (e.g., `ping`). The best remediation is to replace the shell call with a safe library function (e.g., `InetAddress.isReachable()` in Java or a dedicated ICMP library) and strictly allowlist approved internal host values, eliminating the possibility of injecting arbitrary commands like `; rm -rf /`.
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.
✗
Keep the current shell command, but add HTML encoding to the response page.
Why it's wrong here
Output encoding helps prevent browser-side issues, but it does not stop command injection on the server.
✓
Replace the shell call with a safe library function and strictly allowlist approved host values.
Why this is correct
The flaw is server-side command injection caused by passing user input into a shell. A safe library call removes shell interpretation, and an allowlist limits inputs to known-good targets.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Increase the web server timeout so the ping utility has more time to complete.
Why it's wrong here
Timeout tuning does not prevent an attacker from appending extra shell commands to the request.
✗
Require users to authenticate before they can access the page.
Why it's wrong here
Authentication may reduce exposure, but it does not correct the underlying unsafe command execution.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse command injection with cross-site scripting (XSS) and choose HTML encoding (Option A), or they mistakenly think authentication (Option D) or timeout adjustments (Option C) can fix a code-level injection vulnerability.
Trap categories for this question
Command / output trap
Output encoding helps prevent browser-side issues, but it does not stop command injection on the server.
Detailed technical explanation
How to think about this question
Command injection exploits occur when user input is concatenated into a shell command string without sanitization, allowing arbitrary OS command execution via shell metacharacters like `;`, `|`, or `&&`. A safe library function, such as Java's `InetAddress.isReachable()` or Python's `subprocess.run()` with a list of arguments (not a string), avoids shell interpretation entirely. In real-world scenarios, this flaw is common in network diagnostic tools (e.g., `ping`, `traceroute`) and can lead to full server compromise if exploited.
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.
TExam Day Tips
→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 security team runs a vulnerability scan on a web application and discovers an unpatched SQL injection flaw. The team prioritises remediation by CVSS score — critical flaws are patched within 24 hours, high within 7 days. Questions like this test whether you understand vulnerability management processes, scanning tools, and remediation prioritisation.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this SY0-701 question in full detail.
Threats, Vulnerabilities, and Mitigations — This question tests Threats, Vulnerabilities, and Mitigations — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Replace the shell call with a safe library function and strictly allowlist approved host values. — Option B is correct because the application flaw is command injection: a user-controlled parameter is passed directly to a shell command (e.g., `ping`). The best remediation is to replace the shell call with a safe library function (e.g., `InetAddress.isReachable()` in Java or a dedicated ICMP library) and strictly allowlist approved internal host values, eliminating the possibility of injecting arbitrary commands like `; rm -rf /`.
What should I do if I get this SY0-701 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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