Elasticache Replication Group uses unencrypted traffic.

Explanation

Traffic flowing between Elasticache replication nodes should be encrypted to ensure sensitive data is kept private.

Possible Impact

In transit data in the Replication Group could be read if intercepted

Suggested Resolution

Enable in transit encryption for replication group

Insecure Example

The following example will fail the AVD-AWS-0051 check.

---
Resources:
  BadExample:
    Type: 'AWS::ElastiCache::ReplicationGroup'
    Properties:
      AutomaticFailoverEnabled: true    
      CacheNodeType: cache.r3.large
      CacheSubnetGroupName: !Ref CacheSubnetGroup
      Engine: redis
      EngineVersion: '3.2'
      NumNodeGroups: '2'
      ReplicasPerNodeGroup: '3'
      Port: 6379
      PreferredMaintenanceWindow: 'sun:05:00-sun:09:00'
      ReplicationGroupDescription: A sample replication group
      SecurityGroupIds:
      - !Ref ReplicationGroupSG
      SnapshotRetentionLimit: 5
      SnapshotWindow: '10:00-12:00'

Secure Example

The following example will pass the AVD-AWS-0051 check.

---
Resources:
  GoodExample:
    Type: 'AWS::ElastiCache::ReplicationGroup'
    Properties:
      AutomaticFailoverEnabled: true    
      CacheNodeType: cache.r3.large
      CacheSubnetGroupName: !Ref CacheSubnetGroup
      Engine: redis
      EngineVersion: '3.2'
      NumNodeGroups: '2'
      ReplicasPerNodeGroup: '3'
      Port: 6379
      PreferredMaintenanceWindow: 'sun:05:00-sun:09:00'
      ReplicationGroupDescription: A sample replication group
      SecurityGroupIds:
      - !Ref ReplicationGroupSG
      SnapshotRetentionLimit: 5
      SnapshotWindow: '10:00-12:00'   
      TransitEncryptionEnabled: true


Getting Started
Services