The answer is to implement vendor access reviews and enforce multi-factor authentication (MFA). This is the most effective long-term mitigation because it directly addresses the root cause of unauthorized access by ensuring that third-party accounts are regularly audited for necessity and that authentication relies on more than just a password, which is often the vector for compromise. On the Certified Information Security Manager (CISM) exam, this scenario tests your understanding of preventive controls within the incident management and third-party governance domains; a common trap is to focus on short-term containment actions like resetting the vendor’s password or terminating the session, which do not prevent recurrence. Instead, remember that sustainable vendor risk management requires continuous oversight and strong identity controls. A useful memory tip is “Review and Revoke, then MFA to block”—the review process identifies stale or over-privileged accounts, while MFA closes the door on credential theft.
CISM Incident Management Practice Question
This CISM practice question tests your understanding of incident management. 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.
After containing a security incident, the team conducts a root cause analysis. They find the breach originated from a compromised third-party vendor account. What is the most effective long-term mitigation?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Implement vendor access reviews and enforce MFA
Implementing vendor access reviews and enforcing MFA addresses the root cause of unauthorized access.
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.
✗
Increase logging on vendor accounts
Why it's wrong here
Logging detects but does not prevent unauthorized access.
✗
Change all passwords manually
Why it's wrong here
Password changes are temporary and may not prevent future compromises.
✓
Implement vendor access reviews and enforce MFA
Why this is correct
Correct: Reduces risk of future compromises from vendor accounts.
Related concept
Static NAT maps one inside address to one outside address.
✗
Terminate the vendor relationship
Why it's wrong here
Termination may not be feasible and doesn't address systemic issues.
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.
Incident Management — This question tests Incident Management — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: Implement vendor access reviews and enforce MFA — Implementing vendor access reviews and enforcing MFA addresses the root cause of unauthorized access.
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.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
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Question Discussion
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