The answer is AWS CloudTrail, as it is the only service that records all API calls made by an IAM role, including the source IP address, user agent, and specific actions performed. When an EC2 instance with an attached IAM role makes calls to an S3 bucket in another account, CloudTrail captures these events in its logs, allowing a security engineer to trace the exact origin and determine whether the activity is malicious. On the AWS Certified Security Specialty SCS-C02 exam, this scenario tests your understanding of CloudTrail’s role in auditing identity-based actions, often appearing as a distractor against services like AWS Config or VPC Flow Logs, which do not log API-level calls. A common trap is confusing CloudTrail with Amazon GuardDuty, but remember: CloudTrail records the calls, while GuardDuty detects anomalies in them. Memory tip: Think of CloudTrail as the “trail of breadcrumbs” left by every API action an IAM role takes.
SCS-C02 Threat Detection and Incident Response Practice Question
This SCS-C02 practice question tests your understanding of threat detection and incident response. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. 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 engineer is investigating a potential data exfiltration incident. The engineer notices that an EC2 instance with an attached IAM role has been making API calls to an S3 bucket in another AWS account. The engineer wants to identify the source of the API calls and determine if the calls are malicious. Which AWS service should the engineer use to view the API calls made by the IAM role?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
AWS CloudTrail
AWS CloudTrail is the correct service because it records all API calls made by IAM roles, including the source IP address, user agent, and the specific actions performed. In this scenario, CloudTrail logs will show the exact API calls made by the EC2 instance's IAM role to the S3 bucket in another account, enabling the security engineer to identify the source and determine if the calls are malicious.
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.
✗
VPC Flow Logs
Why it's wrong here
VPC Flow Logs capture information about IP traffic going to and from network interfaces, not API calls.
✗
Amazon GuardDuty
Why it's wrong here
GuardDuty is a threat detection service that analyzes logs, but it does not directly store API call logs.
✗
AWS Config
Why it's wrong here
AWS Config records resource configuration changes, not API calls.
✓
AWS CloudTrail
Why this is correct
CloudTrail records API calls made by IAM roles and provides details such as source IP, user agent, and request parameters.
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 confuse VPC Flow Logs (which show network traffic) with CloudTrail (which shows API calls), or they assume GuardDuty provides raw logs instead of just alerts, leading them to pick a service that cannot directly answer the question of viewing the specific API calls made by the IAM role.
Detailed technical explanation
How to think about this question
CloudTrail delivers event history in JSON format, including the `userIdentity` field that captures the IAM role ARN, the `sourceIPAddress` (which may be the EC2 instance's public IP or a VPC endpoint IP), and the `requestParameters` showing the S3 bucket and object. For cross-account access, CloudTrail logs are generated in both the source account (where the IAM role resides) and the target account (where the S3 bucket is), but the engineer should examine the source account's CloudTrail to see the role's API calls. A subtle behavior is that if the EC2 instance uses a VPC endpoint, the `sourceIPAddress` will show the endpoint's private IP, not the instance's public IP.
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 media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
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.
Threat Detection and Incident Response — This question tests Threat Detection and Incident Response — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: AWS CloudTrail — AWS CloudTrail is the correct service because it records all API calls made by IAM roles, including the source IP address, user agent, and the specific actions performed. In this scenario, CloudTrail logs will show the exact API calls made by the EC2 instance's IAM role to the S3 bucket in another account, enabling the security engineer to identify the source and determine if the calls are malicious.
What should I do if I get this SCS-C02 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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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