What is the MOST efficient way to meet these requirements?
Install antivirus software and ensure that signatures are up-to-date. Configure Amazon CloudWatch alarms to send alerts for security events.
Install host-based IDS software to check for file integrity. Export the logs to Amazon CloudWatch Logs for monitoring and alerting.
Export system log files to Amazon S3. Parse the log files using an AWS Lambda function that will send alerts of any unauthorized system login attempts through Amazon SNS.
Use Amazon CloudWatch Logs to detect file system changes. If a change is detected, automatically terminate and recreate the instance from the most recent AMI. Use Amazon SNS to send notification of the event.
Explanations:
Antivirus software and CloudWatch alarms are focused on detecting malware and security events, but they are not designed to track file integrity specifically. It does not provide file modification detection.
Host-based IDS software can monitor file integrity and detect unauthorized changes to files. Exporting logs to CloudWatch Logs allows centralized monitoring and alerting. This is an efficient solution for file modification detection.
Exporting system logs to Amazon S3 and using Lambda for parsing and alerts focuses on login attempts, not file modifications. It does not directly address the need to detect file changes.
CloudWatch Logs cannot directly detect file system changes. Automatically terminating and recreating the instance is excessive for this use case, as it is not focused on efficiently detecting file modifications.
I scheme that the answer is:
Install host-based IDS software to check for file integrity. Export the logs to Amazon CloudWatch Logs for monitoring and alerting.