The correct answer is that an attacker has compromised a remote employee’s device and is brute-forcing the admin account. This is the most likely explanation because a brute force attack via compromised VPN endpoint exploits a trusted VPN broker’s IP address, making the failed login attempts appear to originate from a legitimate source. On the Certified Information Security Manager CISM exam, this scenario tests your ability to distinguish between a true positive alert and a false positive, especially when the source IP is trusted. A common trap is assuming that a trusted IP automatically means the traffic is safe, but attackers often pivot through compromised endpoints to bypass network defenses. Remember the mnemonic “Trusted IP, Untrusted Action” to recall that a legitimate source can still host malicious activity.
CISM Information Security Program Practice Question
This CISM practice question tests your understanding of information security program. 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
Refer to the exhibit.
```
Event Log: SIEM Alert #4521
Timestamp: 2024-08-15 14:23:45 UTC
Rule: Failed login attempts > 5 in 10 minutes
Source IP: 203.0.113.5
Target: User 'admin' on server DC-01
Count: 12 attempts
Status: Alert generated, no automated action
Comment: IP belongs to external VPN broker
```
The security analyst reviews the SIEM alert and finds that the source IP is from a trusted VPN broker used by remote employees. What is the most likely explanation for the alert?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Refer to the exhibit.
```
Event Log: SIEM Alert #4521
Timestamp: 2024-08-15 14:23:45 UTC
Rule: Failed login attempts > 5 in 10 minutes
Source IP: 203.0.113.5
Target: User 'admin' on server DC-01
Count: 12 attempts
Status: Alert generated, no automated action
Comment: IP belongs to external VPN broker
```
A
The VPN broker itself is misconfigured
Why wrong: VPN broker typically does not generate login attempts.
B
A legitimate user forgot their password
Why wrong: 12 attempts in 10 minutes is excessive.
C
An attacker has compromised a remote employee's device and is brute-forcing the admin account
Source IP is VPN broker, but device behind it could be compromised.
D
The alert is a false positive due to SIEM rule threshold
Why wrong: Pattern is suspicious; not a false positive.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
An attacker has compromised a remote employee's device and is brute-forcing the admin account
Option B is correct because a brute force attack could originate from a compromised VPN endpoint. Option A is wrong because the alert indicates failed attempts, not successful authentication. Option C is wrong because failed attempts are likely malicious, not mistaken. Option D is wrong as the alert is not false positive given the pattern.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
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 VPN broker itself is misconfigured
Why it's wrong here
VPN broker typically does not generate login attempts.
✗
A legitimate user forgot their password
Why it's wrong here
12 attempts in 10 minutes is excessive.
✓
An attacker has compromised a remote employee's device and is brute-forcing the admin account
Why this is correct
Source IP is VPN broker, but device behind it could be compromised.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Static NAT maps one inside address to one outside address.
✗
The alert is a false positive due to SIEM rule threshold
Why it's wrong here
Pattern is suspicious; not a false positive.
Common exam traps
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
Static NAT maps one inside address to one outside address.
PAT allows many inside hosts to share one public address using ports.
Inside local and inside global describe the private and translated addresses.
NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
→Identify inside and outside interfaces first.
→Check whether the scenario needs static NAT, dynamic NAT or PAT.
→Do not confuse NAT matching ACLs with normal packet-filtering intent.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Real-world example
How this comes up in practice
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
Got this wrong? Here's your next step.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related CISM NAT questions on configuration and troubleshooting.
Information Security Program — This question tests Information Security Program — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: An attacker has compromised a remote employee's device and is brute-forcing the admin account — Option B is correct because a brute force attack could originate from a compromised VPN endpoint. Option A is wrong because the alert indicates failed attempts, not successful authentication. Option C is wrong because failed attempts are likely malicious, not mistaken. Option D is wrong as the alert is not false positive given the pattern.
What should I do if I get this CISM question wrong?
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related CISM NAT questions on configuration and troubleshooting.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
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