Ensure a Log Metric Filter and Alarm Exist for S3 Bucket Policy Changes Rule

Rule Description:

Troubleshooting Steps:

2. 1.

   Check CloudTrail Configuration:

   • Ensure that AWS CloudTrail is enabled for the AWS account where the S3 bucket resides.
   • Verify that CloudTrail is configured to capture S3 bucket-related events, including bucket policy modifications.
4. 2.

   Verify S3 Bucket Logging:

   • Confirm that the S3 bucket has logging enabled.
   • Check that the destination bucket for S3 logs is properly configured.
   • Validate that the bucket is configured to log "Write" events, as bucket policy changes fall under this category.
6. 3.

   Examine Log Metric Filter:

   • Navigate to the CloudWatch console and select the appropriate region.
   • Go to the "Log groups" section and locate the log group that corresponds to the S3 bucket where policy changes should be monitored.
   • Check if there is a log metric filter applied to the log group for bucket policy changes.
   • Ensure that the filter pattern is correctly configured to capture S3 bucket policy modification events.
8. 4.

   Validate Alarm Configuration:

   • Locate the CloudWatch alarm associated with the log metric filter for bucket policy changes.
   • Make sure the alarm is set to trigger when the log metric filter detects any policy changes.
   • Verify that the alarm's actions are properly configured to send notifications to the relevant stakeholders (e.g., via SNS, email, etc.).
10. 5.

    Test the Monitoring Setup:

    • Manually make a policy change to the S3 bucket whose policy changes should be monitored.
    • Check if the log metric filter accurately detects the policy change event.
    • Verify that the CloudWatch alarm triggers and sends notifications as expected.

Necessary Codes:

Step-by-Step Guide for Remediation:

2. 1.

   Enable AWS CloudTrail:

   • Sign in to the AWS Management Console.
   • Open the CloudTrail service.
   • Create a trail (if not already created) and select the appropriate settings, including the S3 bucket where the CloudTrail logs will be stored.
4. 2.

   Enable Logging for the S3 Bucket:

   • Navigate to the Amazon S3 service in the AWS Management Console.
   • Locate the S3 bucket for which you want to monitor the policy changes.
   • Open the bucket properties and select the "Server access logging" option.
   • Enable access logging and configure the destination bucket for storing the logs.
6. 3.

   Create a Log Metric Filter:

   • Go to the Amazon CloudWatch service in the AWS Management Console.
   • Select the appropriate region.
   • In the left navigation pane, click on "Log groups."
   • Find and select the log group corresponding to the S3 bucket.
   • Choose "Create metric filter" from the "Actions" dropdown.
   • Define a meaningful filter pattern to capture bucket policy changes, such as

     { $.eventName = PutBucketPolicy }

     .
   • Configure the filter to extract required information, such as the bucket name or policy details.
8. 4.

   Configure an Alarm:

   • In the same log group page, select the "Create alarm" button.
   • Specify the conditions that trigger the alarm, such as the metric filter you created in the previous step.
   • Set appropriate threshold values and define the desired actions when the alarm state is triggered.
   • Provide appropriate notification options, such as SNS topics or email addresses.
10. 5.

    Test the Monitoring Setup:

    • Make a policy change to the S3 bucket whose policy changes should be monitored.
    • Verify that the log metric filter detects the policy change event.
    • Check that the CloudWatch alarm triggers and sends notifications as expected.