CVE-2025-0678
📋 TL;DR
A heap-based buffer overflow vulnerability in grub2's squash4 filesystem module allows attackers to execute arbitrary code by crafting malicious filesystems. This affects systems using grub2 with squash4 support and can bypass secure boot protections. The vulnerability requires local access to modify boot files or boot from malicious media.
💻 Affected Systems
- grub2
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with arbitrary code execution during boot, bypassing secure boot and OS-level security controls, leading to persistent malware installation.
Likely Case
Local privilege escalation or boot process manipulation by users with physical access or ability to modify boot configuration/files.
If Mitigated
Limited impact if secure boot is properly configured and physical access controls prevent boot from unauthorized media.
🎯 Exploit Status
Exploitation requires crafting malicious squash4 filesystem and ability to boot from it or modify existing boot files. Secure boot bypass adds complexity.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check vendor-specific updates (Red Hat, Ubuntu, etc.)
Vendor Advisory: https://access.redhat.com/security/cve/CVE-2025-0678
Restart Required: Yes
Instructions:
1. Check for vendor security updates for grub2. 2. Apply updates via package manager (e.g., 'yum update grub2' or 'apt upgrade grub2'). 3. Update boot configuration with 'grub2-mkconfig' or equivalent. 4. Reboot system to load patched grub2.
🔧 Temporary Workarounds
Disable squash4 module
linuxRemove or disable squash4 filesystem support in grub2 configuration
Edit /etc/default/grub and add GRUB_DISABLE_OS_PROBER=true
Run: grub2-mkconfig -o /boot/grub2/grub.cfg
Secure boot enforcement
linuxEnsure secure boot is enabled and properly configured to prevent unauthorized boot modifications
Check secure boot status: mokutil --sb-state
Enable if disabled via UEFI/BIOS settings
🧯 If You Can't Patch
- Restrict physical access to systems and boot media
- Implement strict access controls on boot configuration files and directories
🔍 How to Verify
Check if Vulnerable:
Check grub2 version and if squash4 module is loaded: 'grub2-install --version' and check for squash4 in modulesCheck Version:
grub2-install --versionVerify Fix Applied:
Verify updated grub2 package version matches vendor patched version: 'rpm -q grub2' or 'dpkg -l grub2'📡 Detection & Monitoring
Log Indicators:
- Unexpected boot failures or errors
- Modified boot configuration files
- Secure boot violation logs
Network Indicators:
- Not network exploitable - no network indicators
SIEM Query:
Search for: boot process anomalies, secure boot violations, unauthorized grub configuration changes