A company stores its processed data in an S3 bucket. The company has a strict data access policy. The company uses IAM roles to grant teams within…

The most precise and effective solution is to use AWS CloudTrail to monitor object-level API calls (data events) for the S3 bucket. CloudTrail logs capture comprehensive details for each event, including the specific userIdentity of the user or role that made the request. By forwarding these events to Amazon CloudWatch Events (now Amazon EventBridge), a rule can be configured to filter for specific policy violations, such as errorCode: "AccessDenied". This rule can then trigger a CloudWatch alarm or an Amazon SNS notification, which can be configured to include the user information from the original CloudTrail event, thereby meeting all the stated requirements.

1. AWS CloudTrail User Guide

"Logging Amazon S3 API calls by using AWS CloudTrail": This guide states

"CloudTrail provides a record of actions taken by a user

role

or an AWS service in Amazon S3... You can use the information collected by CloudTrail to determine the request that was made... who made the request

when it was made

and additional details." This confirms CloudTrail's capability to capture the required user identity.

2. Amazon S3 User Guide

"Logging and monitoring in Amazon S3

" section "Choosing between Server Access Logging and CloudTrail": This official documentation explicitly recommends CloudTrail for this use case: "CloudTrail logs provide detailed API tracking for S3 bucket-level and object-level operations... We recommend that you use CloudTrail for logging bucket-level and object-level actions."

3. Amazon EventBridge User Guide

"Creating a rule for an AWS service": This documentation details the process of creating a rule that matches an event pattern from a source like CloudTrail (e.g.

an S3 API call with an "AccessDenied" error) and routing it to a target

such as an SNS topic for notification

which can pass along event details.

4. Amazon S3 User Guide

"Monitoring metrics with Amazon CloudWatch": The description of S3 request metrics confirms they are aggregate counts (e.g.

4xxErrors

GetRequests) and do not contain per-request details like the caller's identity.

5. AWS Config Developer Guide

"What Is AWS Config?": The guide defines the service's purpose: "AWS Config is a service that enables you to assess

audit

and evaluate the configurations of your AWS resources

" distinguishing it from an access monitoring tool.