CloudWatch S3 policy Change Alarm Missing
- Query id: 27c6a499-895a-4dc7-9617-5c485218db13
- Query name: CloudWatch S3 policy Change Alarm Missing
- Platform: Terraform
- Severity: Medium
- Category: Observability
- CWE: 778
- URL: Github
Description¶
Ensure a log metric filter and alarm exist for S3 bucket policy changes
Documentation
Code samples¶
Code samples with security vulnerabilities¶
Positive test num. 1 - tf file
resource "aws_cloudwatch_log_metric_filter" "cis_s3_bucket_policy_change_metric_filter" {
name = "CIS-S3BucketPolicyChanges"
pattern = "{ ($.eventSource = \"s3.amazonaws.com\") || (($.eventName = PutBucketAcl) || ($.eventName = PutBucketPolicy) || ($.eventName = PutBucketCors) || ($.eventName = PutBucketLifecycle) || ($.eventName = PutBucketReplication) || ($.eventName = DeleteBucketPolicy) || ($.eventName = DeleteBucketCors) || ($.eventName = DeleteBucketLifecycle) || ($.eventName = DeleteBucketReplication)) }"
log_group_name = aws_cloudwatch_log_group.CIS_CloudWatch_LogsGroup.name
metric_transformation {
name = "CIS-S3BucketPolicyChanges"
namespace = "CIS_Metric_Alarm_Namespace"
value = "1"
}
}
resource "aws_cloudwatch_metric_alarm" "cis_s3_bucket_policy_change_cw_alarm" {
alarm_name = "CIS-3.8-S3BucketPolicyChanges"
comparison_operator = "GreaterThanOrEqualToThreshold"
evaluation_periods = "1"
metric_name = "XXX NOT YOUR FILTER"
namespace = "CIS_Metric_Alarm_Namespace"
period = "300"
statistic = "Sum"
threshold = "1"
alarm_description = "Monitoring changes to S3 bucket policies may reduce time to detect and correct permissive policies on sensitive S3 buckets."
alarm_actions = [aws_sns_topic.CIS_Alerts_SNS_Topic.arn]
insufficient_data_actions = []
}
resource "aws_cloudwatch_log_metric_filter" "cis_no_mfa_console_signin_metric_filter" {
name = "CIS-ConsoleSigninWithoutMFA"
pattern = "{ ($.eventName = \"ConsoleLogin\") && ($.additionalEventData.MFAUsed != \"Yes\") }"
log_group_name = aws_cloudwatch_log_group.CIS_CloudWatch_LogsGroup.name
metric_transformation {
name = "CIS-ConsoleSigninWithoutMFA"
namespace = "CIS_Metric_Alarm_Namespace"
value = "1"
}
}
resource "aws_cloudwatch_metric_alarm" "cis_no_mfa_console_signin_cw_alarm" {
alarm_name = "CIS-3.2-ConsoleSigninWithoutMFA"
comparison_operator = "GreaterThanOrEqualToThreshold"
evaluation_periods = "1"
metric_name = aws_cloudwatch_log_metric_filter.cis_no_mfa_console_signin_metric_filter.id
namespace = "CIS_Metric_Alarm_Namespace"
period = "300"
statistic = "Sum"
threshold = "1"
alarm_description = "Monitoring for single-factor console logins will increase visibility into accounts that are not protected by MFA."
alarm_actions = [aws_sns_topic.CIS_Alerts_SNS_Topic.arn]
insufficient_data_actions = []
}
Positive test num. 2 - tf file
resource "aws_cloudwatch_log_metric_filter" "cis_s3_bucket_policy_change_metric_filter" {
name = "CIS-S3BucketPolicyChanges"
pattern = "{ ($.eventSource = \"s3.amazonaws.com\") && (($.eventName = PutBucketPolicy) || ($.eventName = PutBucketCors) || ($.eventName = PutBucketLifecycle) || ($.eventName = PutBucketReplication) || ($.eventName = DeleteBucketPolicy) || ($.eventName = DeleteBucketCors) || ($.eventName = DeleteBucketLifecycle) || ($.eventName = DeleteBucketReplication)) }"
log_group_name = aws_cloudwatch_log_group.CIS_CloudWatch_LogsGroup.name
metric_transformation {
name = "CIS-S3BucketPolicyChanges"
namespace = "CIS_Metric_Alarm_Namespace"
value = "1"
}
}
resource "aws_cloudwatch_metric_alarm" "CIS_S3_Bucket_Policy_Change_CW_Alarm" {
alarm_name = "CIS-3.8-S3BucketPolicyChanges"
comparison_operator = "GreaterThanOrEqualToThreshold"
evaluation_periods = "1"
metric_name = aws_cloudwatch_log_metric_filter.cis_s3_bucket_policy_change_metric_filter.id
namespace = "CIS_Metric_Alarm_Namespace"
period = "300"
statistic = "Sum"
threshold = "1"
alarm_description = "Monitoring changes to S3 bucket policies may reduce time to detect and correct permissive policies on sensitive S3 buckets."
alarm_actions = [aws_sns_topic.CIS_Alerts_SNS_Topic.arn]
insufficient_data_actions = []
}
Positive test num. 3 - tf file
resource "aws_cloudwatch_log_metric_filter" "cis_s3_bucket_policy_change_metric_filter" {
name = "CIS-S3BucketPolicyChanges"
pattern = "{ ($.eventSource = \"s3.amazonaws.com\") && (($.eventName = PutBucketAcl) || ($.eventName = PutBucketCors) || ($.eventName = PutBucketLifecycle) || ($.eventName = PutBucketReplication) || ($.eventName = DeleteBucketPolicy) || ($.eventName = DeleteBucketCors) || ($.eventName = DeleteBucketLifecycle) || ($.eventName = DeleteBucketReplication)) }"
log_group_name = aws_cloudwatch_log_group.CIS_CloudWatch_LogsGroup.name
metric_transformation {
name = "CIS-S3BucketPolicyChanges"
namespace = "CIS_Metric_Alarm_Namespace"
value = "1"
}
}
resource "aws_cloudwatch_metric_alarm" "CIS_S3_Bucket_Policy_Change_CW_Alarm" {
alarm_name = "CIS-3.8-S3BucketPolicyChanges"
comparison_operator = "GreaterThanOrEqualToThreshold"
evaluation_periods = "1"
metric_name = aws_cloudwatch_log_metric_filter.cis_s3_bucket_policy_change_metric_filter.id
namespace = "CIS_Metric_Alarm_Namespace"
period = "300"
statistic = "Sum"
threshold = "1"
alarm_description = "Monitoring changes to S3 bucket policies may reduce time to detect and correct permissive policies on sensitive S3 buckets."
alarm_actions = [aws_sns_topic.CIS_Alerts_SNS_Topic.arn]
insufficient_data_actions = []
}
Positive test num. 4 - tf file
resource "aws_cloudwatch_log_metric_filter" "cis_s3_bucket_policy_change_metric_filter" {
name = "CIS-S3BucketPolicyChanges"
pattern = "{ $.eventSource = \"s3.amazonaws.com\" }"
log_group_name = aws_cloudwatch_log_group.CIS_CloudWatch_LogsGroup.name
metric_transformation {
name = "CIS-S3BucketPolicyChanges"
namespace = "CIS_Metric_Alarm_Namespace"
value = "1"
}
}
resource "aws_cloudwatch_metric_alarm" "CIS_S3_Bucket_Policy_Change_CW_Alarm" {
alarm_name = "CIS-3.8-S3BucketPolicyChanges"
comparison_operator = "GreaterThanOrEqualToThreshold"
evaluation_periods = "1"
metric_name = aws_cloudwatch_log_metric_filter.cis_s3_bucket_policy_change_metric_filter.id
namespace = "CIS_Metric_Alarm_Namespace"
period = "300"
statistic = "Sum"
threshold = "1"
alarm_description = "Monitoring changes to S3 bucket policies may reduce time to detect and correct permissive policies on sensitive S3 buckets."
alarm_actions = [aws_sns_topic.CIS_Alerts_SNS_Topic.arn]
insufficient_data_actions = []
}
Positive test num. 5 - tf file
resource "aws_cloudwatch_log_metric_filter" "cis_s3_bucket_policy_change_metric_filter" {
name = "CIS-S3BucketPolicyChanges"
# Here should be &&
pattern = "{ ($.eventSource = \"s3.amazonaws.com\") || (($.eventName = PutBucketAcl) || ($.eventName = PutBucketPolicy) || ($.eventName = PutBucketCors) || ($.eventName = PutBucketLifecycle) || ($.eventName = PutBucketReplication) || ($.eventName = DeleteBucketPolicy) || ($.eventName = DeleteBucketCors) || ($.eventName = DeleteBucketLifecycle) || ($.eventName = DeleteBucketReplication)) }"
log_group_name = aws_cloudwatch_log_group.CIS_CloudWatch_LogsGroup.name
metric_transformation {
name = "CIS-S3BucketPolicyChanges"
namespace = "CIS_Metric_Alarm_Namespace"
value = "1"
}
}
resource "aws_cloudwatch_metric_alarm" "cis_s3_bucket_policy_change_cw_alarm" {
alarm_name = "CIS-3.8-S3BucketPolicyChanges"
comparison_operator = "GreaterThanOrEqualToThreshold"
evaluation_periods = "1"
metric_name = aws_cloudwatch_log_metric_filter.cis_s3_bucket_policy_change_metric_filter.id
namespace = "CIS_Metric_Alarm_Namespace"
period = "300"
statistic = "Sum"
threshold = "1"
alarm_description = "Monitoring changes to S3 bucket policies may reduce time to detect and correct permissive policies on sensitive S3 buckets."
alarm_actions = [aws_sns_topic.CIS_Alerts_SNS_Topic.arn]
insufficient_data_actions = []
}
resource "aws_cloudwatch_log_metric_filter" "cis_no_mfa_console_signin_metric_filter" {
name = "CIS-ConsoleSigninWithoutMFA"
pattern = "{ ($.eventName = \"ConsoleLogin\") && ($.additionalEventData.MFAUsed != \"Yes\") }"
log_group_name = aws_cloudwatch_log_group.CIS_CloudWatch_LogsGroup.name
metric_transformation {
name = "CIS-ConsoleSigninWithoutMFA"
namespace = "CIS_Metric_Alarm_Namespace"
value = "1"
}
}
resource "aws_cloudwatch_metric_alarm" "cis_no_mfa_console_signin_cw_alarm" {
alarm_name = "CIS-3.2-ConsoleSigninWithoutMFA"
comparison_operator = "GreaterThanOrEqualToThreshold"
evaluation_periods = "1"
metric_name = aws_cloudwatch_log_metric_filter.cis_no_mfa_console_signin_metric_filter.id
namespace = "CIS_Metric_Alarm_Namespace"
period = "300"
statistic = "Sum"
threshold = "1"
alarm_description = "Monitoring for single-factor console logins will increase visibility into accounts that are not protected by MFA."
alarm_actions = [aws_sns_topic.CIS_Alerts_SNS_Topic.arn]
insufficient_data_actions = []
}
Code samples without security vulnerabilities¶
Negative test num. 1 - tf file
resource "aws_cloudwatch_log_metric_filter" "cis_s3_bucket_policy_change_metric_filter" {
name = "CIS-S3BucketPolicyChanges"
pattern = "{ ($.eventSource = \"s3.amazonaws.com\") && (($.eventName = PutBucketAcl) || ($.eventName = PutBucketPolicy) || ($.eventName = PutBucketCors) || ($.eventName = PutBucketLifecycle) || ($.eventName = PutBucketReplication) || ($.eventName = DeleteBucketPolicy) || ($.eventName = DeleteBucketCors) || ($.eventName = DeleteBucketLifecycle) || ($.eventName = DeleteBucketReplication)) }"
log_group_name = aws_cloudwatch_log_group.CIS_CloudWatch_LogsGroup.name
metric_transformation {
name = "CIS-S3BucketPolicyChanges"
namespace = "CIS_Metric_Alarm_Namespace"
value = "1"
}
}
resource "aws_cloudwatch_metric_alarm" "cis_s3_bucket_policy_change_cw_alarm" {
alarm_name = "CIS-3.8-S3BucketPolicyChanges"
comparison_operator = "GreaterThanOrEqualToThreshold"
evaluation_periods = "1"
metric_name = aws_cloudwatch_log_metric_filter.cis_s3_bucket_policy_change_metric_filter.id
namespace = "CIS_Metric_Alarm_Namespace"
period = "300"
statistic = "Sum"
threshold = "1"
alarm_description = "Monitoring changes to S3 bucket policies may reduce time to detect and correct permissive policies on sensitive S3 buckets."
alarm_actions = [aws_sns_topic.CIS_Alerts_SNS_Topic.arn]
insufficient_data_actions = []
}
resource "aws_cloudwatch_log_metric_filter" "cis_no_mfa_console_signin_metric_filter" {
name = "CIS-ConsoleSigninWithoutMFA"
pattern = "{ ($.eventSource = \"s3.amazonaws.com\") && (($.eventName = PutBucketAcl) || ($.eventName = PutBucketPolicy) || ($.eventName = PutBucketCors) || ($.eventName = PutBucketLifecycle) || ($.eventName = PutBucketReplication) || ($.eventName = DeleteBucketPolicy) || ($.eventName = DeleteBucketCors) || ($.eventName = DeleteBucketLifecycle) || ($.eventName = DeleteBucketReplication)) }"
log_group_name = aws_cloudwatch_log_group.CIS_CloudWatch_LogsGroup.name
metric_transformation {
name = "CIS-ConsoleSigninWithoutMFA"
namespace = "CIS_Metric_Alarm_Namespace"
value = "1"
}
}
resource "aws_cloudwatch_metric_alarm" "cis_no_mfa_console_signin_cw_alarm" {
alarm_name = "CIS-3.2-ConsoleSigninWithoutMFA"
comparison_operator = "GreaterThanOrEqualToThreshold"
evaluation_periods = "1"
metric_name = aws_cloudwatch_log_metric_filter.cis_no_mfa_console_signin_metric_filter.id
namespace = "CIS_Metric_Alarm_Namespace"
period = "300"
statistic = "Sum"
threshold = "1"
alarm_description = "Monitoring for single-factor console logins will increase visibility into accounts that are not protected by MFA."
alarm_actions = [aws_sns_topic.CIS_Alerts_SNS_Topic.arn]
insufficient_data_actions = []
}