S3 Bucket Object Level CloudTrail Logging Disabled

• Query id: a8fc2180-b3ac-4c93-bd0d-a55b974e4b07
• Query name: S3 Bucket Object Level CloudTrail Logging Disabled
• Platform: Terraform
• Severity: Medium
• Category: Observability
• URL: Github

Description

S3 Bucket object-level CloudTrail logging should be enabled for read and write events
Documentation

Code samples

Code samples with security vulnerabilities

Positive test num. 1 - tf file

data "aws_caller_identity" "current" {}

resource "aws_cloudtrail" "example" {
  name                          = "tf-trail-foobar"
  s3_bucket_name                = aws_s3_bucket.foo.id
  s3_key_prefix                 = "prefix"
  include_global_service_events = false

  event_selector {
    include_management_events = true

    data_resource {
      type   = "AWS::S3::Object"
      values = ["arn:aws:s3:::"]
    }
  }
}

resource "aws_s3_bucket" "foo" {
  bucket        = "tf-test-trail"
  force_destroy = true

  policy = <<POLICY
{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Sid": "AWSCloudTrailAclCheck",
            "Effect": "Allow",
            "Principal": {
              "Service": "cloudtrail.amazonaws.com"
            },
            "Action": "s3:GetBucketAcl",
            "Resource": "arn:aws:s3:::tf-test-trail"
        },
        {
            "Sid": "AWSCloudTrailWrite",
            "Effect": "Allow",
            "Principal": {
              "Service": "cloudtrail.amazonaws.com"
            },
            "Action": "s3:PutObject",
            "Resource": "arn:aws:s3:::tf-test-trail/prefix/AWSLogs/${data.aws_caller_identity.current.account_id}/*",
            "Condition": {
                "StringEquals": {
                    "s3:x-amz-acl": "bucket-owner-full-control"
                }
            }
        }
    ]
}
POLICY
}

Positive test num. 2 - tf file

data "aws_caller_identity" "current2" {}

resource "aws_cloudtrail" "example2" {
  name                          = "tf-trail-foobar"
  s3_bucket_name                = aws_s3_bucket.foo2.id
  s3_key_prefix                 = "prefix"
  include_global_service_events = false

  event_selector {
    read_write_type           = "ReadOnly"
    include_management_events = true

    data_resource {
      type   = "AWS::S3::Object"
      values = ["arn:aws:s3:::"]
    }
  }
}

resource "aws_s3_bucket2" "foo" {
  bucket        = "tf-test-trail"
  force_destroy = true

  policy = <<POLICY
{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Sid": "AWSCloudTrailAclCheck",
            "Effect": "Allow",
            "Principal": {
              "Service": "cloudtrail.amazonaws.com"
            },
            "Action": "s3:GetBucketAcl",
            "Resource": "arn:aws:s3:::tf-test-trail"
        },
        {
            "Sid": "AWSCloudTrailWrite",
            "Effect": "Allow",
            "Principal": {
              "Service": "cloudtrail.amazonaws.com"
            },
            "Action": "s3:PutObject",
            "Resource": "arn:aws:s3:::tf-test-trail/prefix/AWSLogs/${data.aws_caller_identity.current2.account_id}/*",
            "Condition": {
                "StringEquals": {
                    "s3:x-amz-acl": "bucket-owner-full-control"
                }
            }
        }
    ]
}
POLICY
}

Code samples without security vulnerabilities

Negative test num. 1 - tf file

data "aws_caller_identity" "current3" {}

resource "aws_cloudtrail" "example3" {
  name                          = "tf-trail-foobar"
  s3_bucket_name                = aws_s3_bucket.foo3.id
  s3_key_prefix                 = "prefix"
  include_global_service_events = false

  event_selector {
    read_write_type           = "All"
    include_management_events = true

    data_resource {
      type   = "AWS::S3::Object"
      values = ["arn:aws:s3:::"]
    }
  }
}

resource "aws_s3_bucket" "foo3" {
  bucket        = "tf-test-trail"
  force_destroy = true

  policy = <<POLICY
{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Sid": "AWSCloudTrailAclCheck",
            "Effect": "Allow",
            "Principal": {
              "Service": "cloudtrail.amazonaws.com"
            },
            "Action": "s3:GetBucketAcl",
            "Resource": "arn:aws:s3:::tf-test-trail"
        },
        {
            "Sid": "AWSCloudTrailWrite",
            "Effect": "Allow",
            "Principal": {
              "Service": "cloudtrail.amazonaws.com"
            },
            "Action": "s3:PutObject",
            "Resource": "arn:aws:s3:::tf-test-trail/prefix/AWSLogs/${data.aws_caller_identity.current3.account_id}/*",
            "Condition": {
                "StringEquals": {
                    "s3:x-amz-acl": "bucket-owner-full-control"
                }
            }
        }
    ]
}
POLICY
}