CVE-2021-3570
📋 TL;DR
A buffer overflow vulnerability in the ptp4l program of the linuxptp package allows remote attackers to leak information, crash systems, or potentially execute arbitrary code by sending specially crafted PTP messages. This affects systems running vulnerable versions of linuxptp, particularly those using PTP for precise time synchronization in networks.
💻 Affected Systems
- linuxptp
📦 What is this software?
Fedora by Fedoraproject
Fedora by Fedoraproject
Linuxptp by Linuxptp Project
Linuxptp by Linuxptp Project
Linuxptp by Linuxptp Project
Linuxptp by Linuxptp Project
Linuxptp by Linuxptp Project
Linuxptp by Linuxptp Project
Linuxptp by Linuxptp Project
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise, data exfiltration, and persistent backdoor installation.
Likely Case
Service crashes causing time synchronization failures and potential denial of service in affected systems.
If Mitigated
Limited impact with proper network segmentation and minimal exposure, potentially just service disruption.
🎯 Exploit Status
Exploitation requires sending specially crafted PTP messages to vulnerable systems. No public exploit code has been confirmed.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: linuxptp 3.1.1, 2.0.1, 1.9.3, 1.8.1, 1.7.1, 1.6.1, or 1.5.1 depending on your version branch
Vendor Advisory: https://bugzilla.redhat.com/show_bug.cgi?id=1966240
Restart Required: Yes
Instructions:
1. Check current linuxptp version. 2. Update using your distribution's package manager (yum update linuxptp, apt-get update && apt-get upgrade linuxptp). 3. Restart ptp4l service or reboot system.
🔧 Temporary Workarounds
Network Segmentation
linuxRestrict PTP traffic to trusted networks only using firewall rules.
iptables -A INPUT -p udp --dport 319 -s trusted_network -j ACCEPT
iptables -A INPUT -p udp --dport 320 -s trusted_network -j ACCEPT
iptables -A INPUT -p udp --dport 319 -j DROP
iptables -A INPUT -p udp --dport 320 -j DROP
Service Disablement
linuxTemporarily disable ptp4l service if PTP synchronization is not critical.
systemctl stop ptp4l
systemctl disable ptp4l
🧯 If You Can't Patch
- Implement strict network segmentation to isolate PTP traffic to trusted VLANs only.
- Deploy intrusion detection systems to monitor for anomalous PTP traffic patterns.
🔍 How to Verify
Check if Vulnerable:
Check linuxptp version with: ptp4l --version or rpm -q linuxptp or dpkg -l linuxptpCheck Version:
ptp4l --version 2>&1 | head -1Verify Fix Applied:
Verify updated version is installed and matches patched versions listed in affected systems.📡 Detection & Monitoring
Log Indicators:
- ptp4l crash logs in systemd journal or /var/log/messages
- Unexpected ptp4l process termination
Network Indicators:
- Unusual PTP message sizes or patterns on UDP ports 319/320
- PTP traffic from unexpected sources
SIEM Query:
source="ptp4l" AND (event="segmentation fault" OR event="crash" OR event="buffer overflow")🔗 References
- https://bugzilla.redhat.com/show_bug.cgi?id=1966240
- https://lists.debian.org/debian-lts-announce/2021/07/msg00025.html
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RHRUVSDP673LXJ5HGIPQPWPIYUPWYQA7/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/VUBKTRCMJ6VKS7DIBSZQB4ATSKVCJYXJ/
- https://www.debian.org/security/2021/dsa-4938
- https://bugzilla.redhat.com/show_bug.cgi?id=1966240
- https://lists.debian.org/debian-lts-announce/2021/07/msg00025.html
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RHRUVSDP673LXJ5HGIPQPWPIYUPWYQA7/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/VUBKTRCMJ6VKS7DIBSZQB4ATSKVCJYXJ/
- https://www.debian.org/security/2021/dsa-4938
