How to Detect and Alert on AWS Root User Activity
A security engineer wants to detect and alert on AWS account root user activity. Which THREE services can be used together to achieve this? (Select THREE.)
Quick Answer
Detecting and alerting on root user activity depends on a chain of services where each hands off to the next: CloudTrail actually records every API call made by the root user, since root activity is logged just like any other principal's. From there, Amazon CloudWatch Logs comes into play because CloudTrail can deliver its events into a CloudWatch Logs group, making root-user activity queryable and filterable in near real time rather than only available as static log files in S3. Amazon CloudWatch Events, now EventBridge, turns a specific event, such as any API call made by the root user, into an action, matching a rule against the CloudTrail-sourced event and triggering a notification through SNS or a remediation step through Lambda. The concept to hold onto is that root-user monitoring is rarely a single service's job; it is a pipeline where CloudTrail supplies the raw event data, CloudWatch Logs or EventBridge watches for a specific pattern such as a root login or API call, and SNS or Lambda delivers the alert. Whenever a question asks which THREE services combine to detect and alert on a specific kind of account activity, expect a logging source, a matching or filtering mechanism, and a notification target, rather than a single all-in-one service.
⚠ Common exam trap
Test-takers frequently think Amazon GuardDuty is the correct choice because it detects threats, but it does not provide a native, customizable alerting mechanism for root user activity; instead, the combination of CloudTrail, EventBridge, and CloudWatch Logs is the standard AWS-recommended approach.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Amazon CloudWatch Events (EventBridge)
Amazon CloudTrail (C) is correct because it records AWS API activity including root user sign-in events and console logins, which are captured as management events in the CloudTrail event history and delivered to an S3 bucket or CloudWatch Logs. Amazon CloudWatch Logs (D) is correct because CloudTrail can be configured to send its trail logs to a CloudWatch Logs log group, where log data can be retained and made available for metric filters and alarms. Amazon CloudWatch Events (EventBridge) (B) is correct because it can match specific CloudTrail API events (for example, events with a userIdentity type of Root) via event patterns and route them to targets such as SNS or Lambda to generate alerts. AWS Config (A) is not correct because it evaluates resource configuration compliance and records configuration changes, not real-time API activity or root user sign-in events. Amazon GuardDuty (E) is not correct because it is a threat detection service that analyzes VPC flow logs, DNS logs, and CloudTrail management events for malicious or anomalous behavior, but it does not provide the event-matching and alerting pipeline for root user activity described here.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
AWS Config
Why it's wrong here
AWS Config records resource configuration changes and evaluates compliance rules; it does not capture root user sign-in or API activity, so it cannot feed a root-activity alert. It would be correct for tracking configuration drift, while CloudTrail, EventBridge and SNS handle event detection.
- ✓
Amazon CloudWatch Events (EventBridge)
Why this is correct
EventBridge matches CloudTrail events against a rule pattern, for example filtering on the root account's ARN, and routes matches to an SNS topic or Lambda function. This provides the near-real-time detection and notification mechanism the scenario requires.
- ✓
AWS CloudTrail
Why this is correct
CloudTrail captures root user API activity as management events, including console sign-ins and privileged actions, providing the raw event source. Without this audit trail there is no record for downstream services to match, filter or alert on.
- ✓
Amazon CloudWatch Logs
Why this is correct
Amazon CloudWatch Logs stores the log data that CloudTrail delivers, enabling metric filters to match root user API calls and trigger alarms. It satisfies the detection-and-alerting requirement by converting raw event records into actionable notifications, complementing CloudTrail's capture and Amazon SNS's delivery.
- ✗
Amazon GuardDuty
Why it's wrong here
GuardDuty detects malicious activity and anomalous behaviour, but it does not itself deliver root-user login alerts; that requires CloudTrail management events feeding EventBridge rules to SNS. GuardDuty is the right choice for continuous threat detection across accounts, such as identifying compromised credentials or crypto-mining.
Quick reference
AWS S3 Storage Class Comparison
| Storage Class | Min Duration | Retrieval | Use Case |
|---|---|---|---|
| S3 Standard | None | Immediate | Frequently accessed data |
| S3 Standard-IA | 30 days | Immediate | Infrequent access, rapid retrieval |
| S3 One Zone-IA | 30 days | Immediate | Non-critical infrequent data |
| S3 Intelligent-Tiering | None | Immediate–hours | Unknown or changing access patterns |
| S3 Glacier Instant | 90 days | Milliseconds | Archive with instant retrieval |
| S3 Glacier Flexible | 90 days | Minutes–hours | Archive, flexible retrieval |
| S3 Glacier Deep Archive | 180 days | Hours | Long-term compliance archive |
Go deeper
Related to this question
About these practice questions
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Same concept, more angles
1 more way this is tested on SCS-C02
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 company needs to be alerted when root account credentials are used in their AWS account. Which service should be used to create a metric filter and alarm for this event?
easy- A.Amazon GuardDuty
- B.AWS Config
- C.AWS CloudTrail
- ✓ D.Amazon CloudWatch Logs
Why D: Amazon CloudWatch Logs can monitor CloudTrail log events for root account usage by creating a metric filter that matches the `userIdentity.type` field with a value of `Root`. When the filter detects a match, it triggers a CloudWatch alarm to notify the operations team. This is the standard AWS-recommended approach for alerting on root activity.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This SCS-C02 practice question is part of Courseiva's free Amazon Web Services certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the SCS-C02 exam.