# Ensure that the container's root filesystem is mounted as read-only

- Source: https://support.icompaas.com/support/solutions/articles/62000234393-ensure-that-the-container-s-root-filesystem-is-mounted-as-read-only
- Section: [Solutions](https://support.icompaas.com/support/solutions) › [CIS Docker Benchmark v1.7.0](https://support.icompaas.com/support/solutions/62000112687) › [CIS Docker Benchmark](https://support.icompaas.com/support/solutions/folders/62000169241)
- Last updated: 2026-05-29
- Publisher: iCompaas, Inc. (https://www.icompaas.com)

**Profile Applicability:**

-   **Level 1**  
    

**Description:**

The root filesystem for a container should be mounted as read-only. This ensures that no files can be modified during runtime, enhancing security by preventing unauthorized changes to the container filesystem.  

**Rationale:**

Mounting the root filesystem as read-only reduces the risk of container compromise. If an attacker gains access to a container, they won't be able to modify critical system files or inject malicious binaries, thus increasing the container's security.  

**Impact:**

**Pros:**  

-   Prevents unauthorized modifications to the container’s filesystem, improving security.  
    
-   Reduces the risk of privilege escalation through file system modifications.  
    

**Cons:**  

-   Some applications that require writing to the filesystem may not function properly unless configured to write to specific directories or volumes.  
    

**Default Value:**

By default, the root filesystem is mounted as read-write.  

**Pre-requisites:**

-   Docker must be installed and running on the system.  
    
-   Administrative privileges to modify Docker container configurations.  
    

**Remediation:**

**Test Plan:**

**Using AWS Console:**

1.  Navigate to the EC2 instance running Docker.  
    
2.  Review the Docker container configuration to ensure that the root filesystem is mounted as read-only.  
    
3.  Check the container's runtime settings for the \-\-read-only flag to verify if it is enabled.

**Using AWS CLI:**

1.  Connect to the EC2 instance.  
    
2.  Run the following command to check if the root filesystem is mounted as read-only:

docker inspect <container\_name> --format '{{.HostConfig.ReadOnly}}'

  

**Implementation Plan:**

**Using AWS Console:**

1.  Edit the Docker run command or the container's configuration file to include the --read-only flagEnsure that any directories that require write access are mounted as volumes with proper permissions.
2.  Restart the container:

**Using AWS CLI:**

1.  Use SSM to remotely configure the container to mount the root filesystem as read-only.  
    
2.  Run the following command to launch a container with the root filesystem mounted as read-only:  
    

aws ssm send-command --document-name "AWS-RunShellScript" --targets "Key=instanceIds,Values=instance\_id" --parameters 'commands=\["docker run --read-only <image\_name>"\]'

  

**Backout Plan:**

**Using AWS Console:**

1.  Edit the Docker run command or the container's configuration to remove the \--read-only flag.
2.  Restart the container:  
      
    

**Using AWS CLI:**

1.  Use SSM to revert the container to the previous configuration without the \--read-only flag.
2.  Run the following command:  
    

aws ssm send-command --document-name "AWS-RunShellScript" --targets "Key=instanceIds,Values=instance\_id" --parameters 'commands=\["docker run <image\_name>"\]'

  

**References:**

-   CIS Docker Benchmark v1.7  
    
-   Docker Documentation: [https://docs.docker.com/](https://docs.docker.com/)

## Related compliance guidance

- [SOC 2 compliance: a practical implementation guide for cloud-native SaaS teams](https://support.icompaas.com/compliance/soc-2-trust-services-criteria): Configuration checks like this one are the technical half of a SOC 2 / ISO 27001 programme — the guide shows where they fit, what else an auditor expects, and how to evidence them.
- [ISO/IEC 27001:2022 compliance: a practical implementation guide](https://support.icompaas.com/compliance/iso-27001-2022): ISO 27001 Annex A.8 (technological controls) is where cloud hardening evidence lands; the guide shows how to run the ISMS around it.