# Disable cramfs Kernel Module to Reduce Linux Attack Surface

- Source: https://support.icompaas.com/support/solutions/articles/62000234901-disable-cramfs-kernel-module-to-reduce-linux-attack-surface
- Section: [Solutions](https://support.icompaas.com/support/solutions) › [CIS Amazon Linux 2 Benchmark v3.0.0](https://support.icompaas.com/support/solutions/62000112696) › [CIS Amazon Linux 2 Benchmarks](https://support.icompaas.com/support/solutions/folders/62000169265)
- Last updated: 2026-05-29
- Publisher: iCompaas, Inc. (https://www.icompaas.com)

**Profile Applicability:** • Level 1

**Description:** The cramfs filesystem is a compressed read-only Linux filesystem commonly used in embedded systems. The cramfs kernel module allows the system to mount cramfs filesystems.

**Rationale:** Disabling the cramfs kernel module when it is not needed reduces the system's attack surface by preventing exploitation of vulnerabilities related to this filesystem type.

**Impact:** Pros:

-   Reduces kernel attack surface by disabling unnecessary filesystem support.  
    
-   Prevents potential exploitation via the cramfs filesystem.  
    

Cons:

-   Systems requiring cramfs will not be able to mount such filesystems if the module is disabled.  
    

**Default Value:** The cramfs kernel module may be available and enabled by default on many Linux systems.

**Pre-requisites:**

-   Root or sudo privileges to modify kernel module configurations.  
    
-   Access to /etc/modprobe.d/ to blacklist or disable modules.
    

**Remediation:**

### **Test Plan:**

**Using Linux command line:**

1.  Verify if the cramfs module is loaded:  
    
     lsmod | grep cramfs
    
      
    
2.  Check for blacklisting or disabling of the module:  
    
     grep -r cramfs /etc/modprobe.d/
    
3.  Test module load behavior:  
    
     modprobe -n -v cramfs
    
      
     Expected output should indicate the module is disabled, e.g., install /bin/false.  
    

### **Implementation Plan:**

**Using Linux command line:**

1.  Create or edit the file /etc/modprobe.d/cramfs.conf:
    
    echo "install cramfs /bin/false" > /etc/modprobe.d/cramfs.conf
     echo "blacklist cramfs" >> /etc/modprobe.d/cramfs.conf
    
      
    
2.  Unload the cramfs module if currently loaded:  
    
     modprobe -r cramfs
    
3.  Reboot the system or reload module configurations.  
    

### **Backout Plan:**

**Using Linux command line:**

1.  Remove cramfs disable and blacklist entries:  
    
     sed -i '/cramfs/d' /etc/modprobe.d/cramfs.conf
    
2.  Optionally reload the module:  
    
     modprobe cramfs
    
3.  Reboot the system.  
    

**References:**

-   CIS Amazon Linux 2 Benchmark v3.0.0
    
-   [NIST SP 800-53 Revision 5 - CM-7](https://csrc.nist.gov/publications/detail/sp/800-53/rev-5/final#cm-7)

## 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.