# Disable squashfs Kernel Module to Harden Linux Kernel

- Source: https://support.icompaas.com/support/solutions/articles/62000234910-disable-squashfs-kernel-module-to-harden-linux-kernel
- 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 2

**Description:** The squashfs kernel module provides support for the SquashFS compressed read-only filesystem. SquashFS is often used in embedded systems, live CDs, and other environments requiring compressed read-only filesystems.

**Rationale:** Disabling the squashfs kernel module when not needed reduces the kernel attack surface by removing unnecessary filesystem support and potential vulnerabilities related to this module.

**Impact:** Pros:

-   Reduces kernel attack surface by disabling unused filesystem modules.  
    
-   Helps mitigate exploitation risks associated with the squashfs filesystem.  
    

Cons:

-   Systems requiring SquashFS support will be unable to mount squashfs filesystems if the module is disabled.  
    

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

**Pre-requisites:**

-   Root or sudo privileges to modify kernel module configurations.  
    
-   Access to /etc/modprobe.d/ for blacklisting or disabling the module.
    

**Remediation:**

### **Test Plan:**

**Using Linux command line:**

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

### **Implementation Plan:**

**Using Linux command line:**

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

### **Backout Plan:**

**Using Linux command line:**

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