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Security July 08, 2026 7 min read

ElastiCache Security: IAM Policies and Network Security

Understanding ElastiCache Security

Amazon ElastiCache is a fully managed in-memory caching service supporting Redis and Memcached. While its primary role is to accelerate data access, securing your cache clusters is critical because they often sit between your application and your database, handling sensitive data such as session state, API rate-limiting counters, or even fragments of personally identifiable information. ElastiCache security encompasses two broad areas: IAM policies that govern who can manage and interact with your clusters, and network security controls that protect data in transit and restrict network access.

Why It Matters

A misconfigured cache can expose your data to the public internet, allow unauthorised users to modify cache contents, or lead to data interception. For example, an overly permissive security group might let an attacker connect to your Redis instance and run FLUSHALL, destroying critical cache state. Similarly, weak IAM policies could grant a developer unintended access to delete production clusters. Applying the principle of least privilege across both IAM and network configurations drastically reduces your attack surface.

IAM Policies for ElastiCache

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IAM policies define what actions a user, group, or role can perform on ElastiCache resources. Actions fall into two categories: control plane (management actions like create, modify, delete) and data plane (connecting to and interacting with the cache data itself). Data plane access is typically governed by the cache engine's own authentication mechanism, but for Redis versions 6 and above, you can also use IAM-based authentication.

Management vs Data Actions

Policy Examples

Below is a typical IAM policy that grants a developer read-only access to the control plane, allowing them to describe and list resources but not modify or delete them, and also grants the ability to connect to a specific Redis cluster using IAM authentication.


{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": [
        "elasticache:DescribeCacheClusters",
        "elasticache:DescribeReplicationGroups",
        "elasticache:DescribeCacheSubnetGroups",
        "elasticache:DescribeEvents",
        "elasticache:ListTagsForResource"
      ],
      "Resource": "*"
    },
    {
      "Effect": "Allow",
      "Action": "elasticache:Connect",
      "Resource": "arn:aws:elasticache:us-east-1:123456789012:cluster:my-redis-cluster-001"
    }
  ]
}

To further restrict the Redis commands a user can execute after connecting, you can use the elasticache:RedisACL condition. For example, allowing only read-only commands: 


{
  "Effect": "Allow",
  "Action": "elasticache:Connect",
  "Resource": "arn:aws:elasticache:us-east-1:123456789012:cluster:my-readonly-cache",
  "Condition": {
    "ForAnyValue:StringEquals": {
      "elasticache:RedisACL": [
        "get",
        "mget",
        "hget",
        "hgetall",
        "llen",
        "lrange",
        "smembers",
        "zrange",
        "zcard"
      ]
    }
  }
}

Note that this condition only applies when using IAM authentication for Redis connections. Without IAM authentication, the cache's own ACLs (Redis ACL users) take precedence.

IAM Authentication for Redis

Starting with Redis 6, ElastiCache supports IAM-based authentication. Instead of a static Redis password (auth_token), clients authenticate using AWS Signature Version 4 signed requests. This integrates seamlessly with IAM roles, temporary credentials, and AWS Secrets Manager—no long-lived passwords to rotate.

Enabling IAM Authentication

When creating or modifying a Redis cluster, set the --auth-token parameter to a special placeholder or use the transit-encryption-enabled flag along with iam-authentication-enabled. For a new cluster, the AWS CLI command looks like this: 


aws elasticache create-cache-cluster \
  --cache-cluster-id my-iam-cluster \
  --engine redis \
  --engine-version 7.0 \
  --cache-node-type cache.t3.micro \
  --num-cache-nodes 1 \
  --transit-encryption-enabled \
  --auth-token "..." \   # Not required if only IAM auth is desired, but can be combined
  --iam-authentication-enabled

If you want only IAM authentication (no static password), you can omit the auth-token and enable IAM authentication. In that case, clients must use IAM-signed connections. Note that encryption in transit (TLS) is mandatory when IAM authentication is enabled.

Connecting to Redis with IAM

To connect to an IAM-enabled Redis cluster, you need a client that supports the AWS Redis IAM authentication protocol. Below is a Python example using the open-source redis-py library and the aws-iam-auth helper (or you can use the newer redis client with IAM support built-in). The example uses the aws-requests-auth approach to generate a presigned URL that the Redis server validates. 


import redis
import boto3
from botocore.auth import SigV4Auth
from botocore.awsrequest import AWSRequest
import datetime

def get_iam_redis_connection(host, port, region):
    # Obtain credentials from the environment or IAM role
    session = boto3.Session()
    credentials = session.get_credentials()

    # Create a SigV4 signer
    signer = SigV4Auth(credentials, 'elasticache', region)

    # Prepare a dummy request to generate a presigned URL-like token
    # The actual token is the Signature portion, but ElastiCache expects
    # a specific format: the access key, a timestamp, and the signature.
    # The redis-py client with IAM support handles this automatically.
    # Here we show manual construction for educational purposes.
    now = datetime.datetime.utcnow().strftime('%Y%m%dT%H%M%SZ')
    # Construct the string to sign (simplified)
    # In practice use a library like 'redis-iam' or the built-in IAM connector.
    pass  # For brevity, see next example

# Using the official redis-py IAM integration (redis >= 4.1)
import redis
from redis import IAMRedisCredentialsProvider

credentials_provider = IAMRedisCredentialsProvider(
    region_name='us-east-1',
    cache_cluster_id='my-iam-cluster'  # optional, for logging
)

r = redis.Redis(
    host='my-iam-cluster.xxxxxx.use1.cache.amazonaws.com',
    port=6379,
    ssl=True,
    credentials_provider=credentials_provider
)

# Test connection
r.ping()
print("Connected with IAM authentication!")

The IAMRedisCredentialsProvider automatically generates a signed token that the Redis server validates against your IAM permissions. The token is refreshed periodically (every 15 minutes by default) without any manual intervention.

Network Security

Network security for ElastiCache revolves around Security Groups, encryption in transit (TLS), and encryption at rest. These controls ensure that only trusted traffic reaches your cache and that data is protected both on the wire and on disk.

Security Groups

ElastiCache clusters are deployed inside a VPC and associated with one or more security groups. The security group acts as a stateful firewall. To restrict access, only allow inbound TCP traffic on the cache port (6379 for Redis, 11211 for Memcached) from the CIDR ranges or security groups of your application servers. Never use 0.0.0.0/0 unless absolutely necessary and combined with other controls like IAM authentication. 


# Example AWS CLI to create a security group for ElastiCache
aws ec2 create-security-group \
  --group-name cache-access-sg \
  --description "Security group for ElastiCache access" \
  --vpc-id vpc-12345678

# Add an inbound rule allowing application servers (sg-app) to reach Redis port
aws ec2 authorize-security-group-ingress \
  --group-id sg-12345678 \
  --protocol tcp \
  --port 6379 \
  --source-group sg-98765432   # security group of your app instances

Additionally, subnet groups define which subnets the cache nodes can reside in. Placing them in private subnets ensures they have no direct internet exposure.

Encryption in Transit and at Rest

Example CloudFormation snippet enabling both:


{
  "Type": "AWS::ElastiCache::ReplicationGroup",
  "Properties": {
    "ReplicationGroupId": "encrypted-redis",
    "TransitEncryptionEnabled": true,
    "AtRestEncryptionEnabled": true,
    "KmsKeyId": "arn:aws:kms:us-east-1:123456789012:key/your-kms-key",
    ...
  }
}

Best Practices

Conclusion

Securing Amazon ElastiCache requires a layered approach that combines identity-level controls (IAM policies) and network-level defenses. By carefully crafting IAM policies to limit both management and data plane actions, leveraging IAM authentication for Redis, and enforcing strict network boundaries with security groups and encryption, you can ensure that your in-memory data remains fast, available, and protected. Always start with the principle of least privilege, enable encryption by default, and continuously audit your configurations to adapt to evolving threats.

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