ECR image tag not immutable

Docs > Datadog Security > Code Security > Infrastructure as Code (IaC) Security > IaC Security Rules > ECR image tag not immutable

Metadata

Id: cloudformation-aws-ecr-image-tag-not-immutable

Provider: AWS

Platform: CloudFormation

Severity: Medium

Category: Insecure Configurations

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Provider Reference

Description

Amazon ECR repositories should enforce immutable image tags to prevent tags from being overwritten. This reduces the risk of supply-chain tampering and accidental or malicious replacement of images referenced by deployments.

The ImageTagMutability property on AWS::ECR::Repository must be defined and set to IMMUTABLE. Resources missing this property or with ImageTagMutability set to MUTABLE will be flagged as a security issue.

Secure configuration example:

MyRepository:
  Type: AWS::ECR::Repository
  Properties:
    RepositoryName: my-repo
    ImageTagMutability: IMMUTABLE

Compliant Code Examples

Resources:
  MyRepository:
    Type: AWS::ECR::Repository
    Properties:
      ImageTagMutability: "IMMUTABLE"
      RepositoryName: "test-repository"
      RepositoryPolicyText:
        Version: "2012-10-17"
        Statement:
          -
            Sid: AllowPushPull
            Effect: Allow
            Principal:
              AWS:
                - "arn:aws:iam::123456789012:user/Bob"
                - "arn:aws:iam::123456789012:user/Alice"
            Action:
              - "ecr:GetDownloadUrlForLayer"
              - "ecr:BatchGetImage"
              - "ecr:BatchCheckLayerAvailability"
              - "ecr:PutImage"
              - "ecr:InitiateLayerUpload"
              - "ecr:UploadLayerPart"
              - "ecr:CompleteLayerUpload"

{
  "Resources": {
    "MyRepository2": {
      "Type": "AWS::ECR::Repository",
      "Properties": {
        "ImageTagMutability": "IMMUTABLE",
        "RepositoryName": "test-repository",
        "RepositoryPolicyText": {
          "Version": "2008-10-17",
          "Statement": [
            {
              "Sid": "AllowPushPull",
              "Effect": "Allow",
              "Principal": {
                "AWS": [
                  "arn:aws:iam::123456789012:user/Bob",
                  "arn:aws:iam::123456789012:user/Alice"
                ]
              },
              "Action": [
                "ecr:GetDownloadUrlForLayer",
                "ecr:BatchGetImage",
                "ecr:BatchCheckLayerAvailability",
                "ecr:PutImage",
                "ecr:InitiateLayerUpload",
                "ecr:UploadLayerPart",
                "ecr:CompleteLayerUpload"
              ]
            }
          ]
        }
      }
    }
  }
}

Non-Compliant Code Examples

Resources:
  MyRepository3:
    Type: AWS::ECR::Repository
    Properties:
      ImageTagMutability: "MUTABLE"
      RepositoryName: "test-repository"
      RepositoryPolicyText:
        Version: "2012-10-17"
        Statement:
          -
            Sid: AllowPushPull
            Effect: Allow
            Principal:
              AWS:
                - "arn:aws:iam::123456789012:user/Bob"
                - "arn:aws:iam::123456789012:user/Alice"
            Action:
              - "ecr:GetDownloadUrlForLayer"
              - "ecr:BatchGetImage"
              - "ecr:BatchCheckLayerAvailability"
              - "ecr:PutImage"
              - "ecr:InitiateLayerUpload"
              - "ecr:UploadLayerPart"
              - "ecr:CompleteLayerUpload"
  MyRepository4:
    Type: AWS::ECR::Repository
    Properties:
      RepositoryName: "test-repository"
      RepositoryPolicyText:
        Version: "2012-10-17"
        Statement:
          -
            Sid: AllowPushPull
            Effect: Allow
            Principal:
              AWS:
                - "arn:aws:iam::123456789012:user/Bob"
                - "arn:aws:iam::123456789012:user/Alice"
            Action:
              - "ecr:GetDownloadUrlForLayer"
              - "ecr:BatchGetImage"
              - "ecr:BatchCheckLayerAvailability"
              - "ecr:PutImage"
              - "ecr:InitiateLayerUpload"
              - "ecr:UploadLayerPart"
              - "ecr:CompleteLayerUpload"

{
  "Resources": {
    "MyRepository5": {
      "Type": "AWS::ECR::Repository",
      "Properties": {
        "ImageTagMutability": "MUTABLE",
        "RepositoryName": "test-repository",
        "RepositoryPolicyText": {
          "Version": "2008-10-17",
          "Statement": [
            {
              "Sid": "AllowPushPull",
              "Effect": "Allow",
              "Principal": {
                "AWS": [
                  "arn:aws:iam::123456789012:user/Bob",
                  "arn:aws:iam::123456789012:user/Alice"
                ]
              },
              "Action": [
                "ecr:GetDownloadUrlForLayer",
                "ecr:BatchGetImage",
                "ecr:BatchCheckLayerAvailability",
                "ecr:PutImage",
                "ecr:InitiateLayerUpload",
                "ecr:UploadLayerPart",
                "ecr:CompleteLayerUpload"
              ]
            }
          ]
        }
      }
    },
    "MyRepository6": {
      "Type": "AWS::ECR::Repository",
      "Properties": {
        "RepositoryName": "test-repository",
        "RepositoryPolicyText": {
          "Version": "2008-10-17",
          "Statement": [
            {
              "Sid": "AllowPushPull",
              "Effect": "Allow",
              "Principal": {
                "AWS": [
                  "arn:aws:iam::123456789012:user/Bob",
                  "arn:aws:iam::123456789012:user/Alice"
                ]
              },
              "Action": [
                "ecr:GetDownloadUrlForLayer",
                "ecr:BatchGetImage",
                "ecr:BatchCheckLayerAvailability",
                "ecr:PutImage",
                "ecr:InitiateLayerUpload",
                "ecr:UploadLayerPart",
                "ecr:CompleteLayerUpload"
              ]
            }
          ]
        }
      }
    }
  }
}