The answer is to check the endpoint detection and response (EDR) logs on the database server for signs of malware or unauthorized processes. This is the correct first step because the database server, which should never initiate outbound connections, was allowed to communicate with an external IP over port 443 solely because its source port matched an inbound allow rule—a classic technique for detecting firewall bypass using source port 443, where malware spoofs a trusted service port to evade egress filtering. On the CompTIA SecurityX CAS-004 exam, this scenario tests your understanding of zero-trust micro-segmentation and the importance of verifying process integrity before altering firewall rules; a common trap is to immediately block the IP or change the firewall policy, which could destroy forensic evidence. Remember the memory tip: “Source port spoofing is a sign of something spoofing the system—check the process, not the port.”
CAS-004 Security Operations Practice Question
This CAS-004 practice question tests your understanding of security operations. 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 at a financial institution is investigating a potential data exfiltration incident. The organization uses a zero-trust network architecture with micro-segmentation. The analyst notices that a database server with sensitive customer financial data has been communicating with an external IP address (198.51.100.45) over port 443 during non-business hours. The database server is not supposed to initiate outbound connections; all outbound traffic is logged and blocked by default except for specific allowlisted IPs and ports. The analyst reviews the firewall logs and finds that the outbound connection to 198.51.100.45 was allowed because the source port was 443, which is an allowed port for inbound HTTPS traffic. The database server is not a web server and does not run any HTTPS services. Which of the following is the best course of action for the analyst to take first?
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.
Clue: "first"
Why it matters: Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Check the endpoint detection and response (EDR) logs on the database server for signs of malware or unauthorized processes
Option D is correct because the database server is not supposed to initiate outbound connections, yet a connection to an external IP over port 443 was allowed due to source port 443 matching an inbound allow rule. This strongly suggests the server may be compromised, with malware or an unauthorized process using source port 443 to bypass firewall restrictions. Checking EDR logs is the best first step to identify malicious processes or indicators of compromise without prematurely destroying evidence.
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.
✗
Immediately block the external IP address at the perimeter firewall
Why it's wrong here
Blocking the IP may disrupt evidence collection and does not address potential internal compromise.
✗
Disable the database server's network interface
Why it's wrong here
This is too drastic and may cause business disruption without first confirming compromise.
✗
Review the database server's recent application logs for any anomalies
Why it's wrong here
While useful, this step is secondary to determining if the server is actively compromised.
✓
Check the endpoint detection and response (EDR) logs on the database server for signs of malware or unauthorized processes
Why this is correct
Checking EDR logs can quickly indicate whether the server is compromised, guiding further actions.
Clue confirmation
The clue words "best", "first" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume the firewall allowed the connection because port 443 is legitimate for HTTPS, but the key insight is that the source port (not destination port) was used to bypass egress rules, requiring endpoint-level investigation rather than network-level blocking or application log review.
Detailed technical explanation
How to think about this question
In zero-trust micro-segmentation, outbound traffic is typically blocked by default, but firewall rules often inspect only destination port and IP, not source port. Attackers can exploit this by running a reverse shell or tunneling tool (e.g., socat, netcat) that uses a high-privilege source port like 443 to match inbound allow rules, effectively bypassing egress filtering. EDR tools monitor process creation, network connections, and file system changes at the kernel level, providing granular visibility into such unauthorized activities, including the exact command line and parent process.
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 practitioner preparing for the CAS-004 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.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Security Operations — This question tests Security Operations — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Check the endpoint detection and response (EDR) logs on the database server for signs of malware or unauthorized processes — Option D is correct because the database server is not supposed to initiate outbound connections, yet a connection to an external IP over port 443 was allowed due to source port 443 matching an inbound allow rule. This strongly suggests the server may be compromised, with malware or an unauthorized process using source port 443 to bypass firewall restrictions. Checking EDR logs is the best first step to identify malicious processes or indicators of compromise without prematurely destroying evidence.
What should I do if I get this CAS-004 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", "first". 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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Question Discussion
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