The answer is Amazon GuardDuty with anomaly detection, along with Amazon CloudWatch Logs and S3 access logs. GuardDuty uses machine learning to establish a baseline of normal S3 access patterns and can detect anomalous behavior such as large data transfers to an external IP address, which is a classic sign of data exfiltration. CloudWatch Logs ingests S3 server access logs that record every request’s source IP, bytes transferred, and request type; you can then use CloudWatch Logs Insights or metric filters to query for unusually high data volumes to external destinations and trigger CloudWatch Alarms. On the AWS Certified Security Specialty SCS-C02 exam, this scenario tests your ability to combine detective controls—GuardDuty for intelligent anomaly detection and CloudWatch for log-based alerting—rather than relying on a single service. A common trap is choosing AWS Config or AWS CloudTrail alone, but CloudTrail focuses on API calls, not data-level transfers, while Config tracks configuration changes. Memory tip: think “GuardDuty spots the odd, CloudWatch logs the load.”
SCS-C02 Threat Detection and Incident Response Practice Question
This SCS-C02 practice question tests your understanding of threat detection and incident response. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 large volumes of data being transferred from an Amazon S3 bucket to an external IP address. Which AWS services can be used to detect and alert on such behavior? (Choose THREE.)
Amazon CloudWatch Logs with S3 access log analysis.
S3 server access logs can be sent to CloudWatch Logs for monitoring and alerting.
B
AWS CloudTrail with S3 data event logging.
CloudTrail data events record S3 object-level operations, including GetObject for data downloads.
C
Amazon GuardDuty with anomaly detection.
GuardDuty uses machine learning to detect unusual data access patterns, such as large volumes from an unfamiliar IP.
D
AWS Config with compliance rules.
Why wrong: AWS Config checks resource configurations, not data transfer.
E
VPC Flow Logs.
Why wrong: VPC Flow Logs capture traffic to/from S3 via VPC endpoints, but the data transfer itself is encrypted and not visible in flow logs; they show connection metadata but not object-level details.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Amazon CloudWatch Logs with S3 access log analysis.
Amazon CloudWatch Logs can ingest and analyze S3 access logs, which record detailed information about requests made to an S3 bucket, including the source IP address, request type, and bytes transferred. By analyzing these logs with CloudWatch Logs Insights or metric filters, you can detect large data transfers to external IPs and trigger alerts via CloudWatch Alarms, making it a valid detection and alerting mechanism for data exfiltration.
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.
✓
Amazon CloudWatch Logs with S3 access log analysis.
Why this is correct
S3 server access logs can be sent to CloudWatch Logs for monitoring and alerting.
Related concept
Read the scenario before looking for a memorised answer.
✓
AWS CloudTrail with S3 data event logging.
Why this is correct
CloudTrail data events record S3 object-level operations, including GetObject for data downloads.
Related concept
Read the scenario before looking for a memorised answer.
✓
Amazon GuardDuty with anomaly detection.
Why this is correct
GuardDuty uses machine learning to detect unusual data access patterns, such as large volumes from an unfamiliar IP.
Related concept
Read the scenario before looking for a memorised answer.
✗
AWS Config with compliance rules.
Why it's wrong here
AWS Config checks resource configurations, not data transfer.
✗
VPC Flow Logs.
Why it's wrong here
VPC Flow Logs capture traffic to/from S3 via VPC endpoints, but the data transfer itself is encrypted and not visible in flow logs; they show connection metadata but not object-level details.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may think VPC Flow Logs (Option E) are sufficient for S3 data exfiltration detection, but they lack the application-layer context needed to identify S3-specific operations and external IPs in S3 access logs or CloudTrail events.
Trap categories for this question
Command / output trap
VPC Flow Logs capture traffic to/from S3 via VPC endpoints, but the data transfer itself is encrypted and not visible in flow logs; they show connection metadata but not object-level details.
Detailed technical explanation
How to think about this question
S3 access logs are delivered as log records to a target S3 bucket, containing fields like `requester`, `key`, `operation`, `bytes-sent`, and `remote-ip`. CloudTrail S3 data events log object-level API calls (e.g., GetObject, PutObject) with source IP and user identity, enabling correlation of large downloads to external IPs. GuardDuty uses machine learning and threat intelligence to detect unusual patterns, such as an EC2 instance communicating with a known malicious IP or an S3 bucket being accessed from an anomalous geographic location, which can indicate data exfiltration.
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: Amazon CloudWatch Logs with S3 access log analysis. — Amazon CloudWatch Logs can ingest and analyze S3 access logs, which record detailed information about requests made to an S3 bucket, including the source IP address, request type, and bytes transferred. By analyzing these logs with CloudWatch Logs Insights or metric filters, you can detect large data transfers to external IPs and trigger alerts via CloudWatch Alarms, making it a valid detection and alerting mechanism for data exfiltration.
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.
About these practice questions
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These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A security engineer is investigating a potential data exfiltration incident. The engineer suspects that an EC2 instance is sending data to an external IP address. Which TWO AWS services can provide evidence of outbound data transfer? (Select TWO.)
medium
✓ A.S3 server access logs
B.AWS Config
✓ C.VPC Flow Logs
D.AWS CloudTrail
E.AWS Trusted Advisor
Why A: S3 server access logs provide detailed records of requests made to an S3 bucket, including the source IP address, request type, and bytes transferred. If the EC2 instance is exfiltrating data to an external IP by first uploading it to an S3 bucket, these logs can reveal the instance's private or public IP, the amount of data sent, and the target bucket. This makes them a valid source of evidence for outbound data transfer from the EC2 instance to S3.
Variation 2. A security engineer is investigating a potential data exfiltration incident. The engineer suspects that an attacker is using an Amazon S3 bucket to exfiltrate data. Which AWS service can be used to analyze S3 access logs and detect anomalous patterns?
easy
A.Amazon CloudFront
✓ B.Amazon Athena
C.AWS Shield
D.AWS WAF
Why B: Amazon Athena is the correct choice because it allows you to run SQL queries directly against Amazon S3 access logs stored in S3, enabling you to analyze large volumes of log data for anomalous patterns such as unusual data transfer volumes, repeated access from unfamiliar IP ranges, or unexpected object reads. This serverless query service is purpose-built for ad-hoc analysis of structured and semi-structured data in S3 without needing to load data into a separate database, making it ideal for incident response investigations.
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Question Discussion
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