CVE-2021-39260
📋 TL;DR
This vulnerability in NTFS-3G allows attackers to trigger an out-of-bounds memory access by providing a malicious NTFS image. When exploited, it can lead to crashes or potentially arbitrary code execution. Systems using NTFS-3G to mount NTFS filesystems are affected.
💻 Affected Systems
- NTFS-3G
- Tuxera NTFS-3G
- FUSE NTFS-3G
📦 What is this software?
Ntfs 3g by Tuxera
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to full system compromise if attacker can mount malicious NTFS image
Likely Case
Application crash or denial of service when processing malicious NTFS filesystems
If Mitigated
Limited to denial of service if memory protections prevent code execution
🎯 Exploit Status
Exploitation requires ability to mount NTFS filesystem; proof-of-concept available in advisory
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 2021.8.22 or later
Vendor Advisory: https://github.com/tuxera/ntfs-3g/security/advisories/GHSA-q759-8j5v-q5jp
Restart Required: No
Instructions:
1. Update NTFS-3G to version 2021.8.22 or later. 2. For Linux distributions, use package manager: 'sudo apt update && sudo apt upgrade ntfs-3g' (Debian/Ubuntu) or 'sudo yum update ntfs-3g' (RHEL/CentOS). 3. For source installations, download from https://github.com/tuxera/ntfs-3g/releases and compile.
🔧 Temporary Workarounds
Disable NTFS mounting
linuxPrevent mounting of NTFS filesystems if not required
sudo rmmod fuse
sudo systemctl disable fuse
sudo chmod 000 /usr/bin/mount.ntfs
Mount NTFS as read-only
linuxMount NTFS filesystems with read-only flag to reduce attack surface
mount -t ntfs-3g -o ro /dev/sdX1 /mnt/ntfs
🧯 If You Can't Patch
- Restrict NTFS mounting to trusted users only via sudoers or filesystem permissions
- Implement monitoring for unusual NTFS mount attempts and filesystem crashes
🔍 How to Verify
Check if Vulnerable:
Check NTFS-3G version: 'ntfs-3g --version' or 'dpkg -l | grep ntfs-3g' or 'rpm -q ntfs-3g'Check Version:
ntfs-3g --versionVerify Fix Applied:
Confirm version is 2021.8.22 or later: 'ntfs-3g --version | grep -q "2021.8.22\|2021.8.23\|2021.8.24\|2021.9\|2021.10\|2021.11\|2021.12\|2022"'📡 Detection & Monitoring
Log Indicators:
- Kernel logs showing NTFS-3G crashes
- System logs with segmentation faults in ntfs-3g processes
- Unexpected NTFS mount attempts
Network Indicators:
- Unusual SMB/CIFS traffic to NTFS shares
- Network transfers of NTFS image files
SIEM Query:
process.name="ntfs-3g" AND (event.action="segmentation fault" OR event.outcome="failure")🔗 References
- https://github.com/tuxera/ntfs-3g/releases
- https://github.com/tuxera/ntfs-3g/security/advisories/GHSA-q759-8j5v-q5jp
- https://lists.debian.org/debian-lts-announce/2021/11/msg00013.html
- https://security.gentoo.org/glsa/202301-01
- https://www.debian.org/security/2021/dsa-4971
- https://github.com/tuxera/ntfs-3g/releases
- https://github.com/tuxera/ntfs-3g/security/advisories/GHSA-q759-8j5v-q5jp
- https://lists.debian.org/debian-lts-announce/2021/11/msg00013.html
- https://security.gentoo.org/glsa/202301-01
- https://www.debian.org/security/2021/dsa-4971
