CVE-2020-7469
📋 TL;DR
This is a use-after-free vulnerability in FreeBSD's ICMPv6 network stack that allows attackers to potentially execute arbitrary code or cause denial of service. It affects FreeBSD systems with IPv6 enabled, particularly those exposed to untrusted network traffic. The vulnerability occurs when processing malformed ICMPv6 routing option packets.
💻 Affected Systems
- FreeBSD
📦 What is this software?
Freebsd by Freebsd
Freebsd by Freebsd
Freebsd by Freebsd
Freebsd by Freebsd
Freebsd by Freebsd
Freebsd by Freebsd
Freebsd by Freebsd
Freebsd by Freebsd
Freebsd by Freebsd
Freebsd by Freebsd
Freebsd by Freebsd
Freebsd by Freebsd
Freebsd by Freebsd
Freebsd by Freebsd
Freebsd by Freebsd
Freebsd by Freebsd
Freebsd by Freebsd
Freebsd by Freebsd
Freebsd by Freebsd
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to full system compromise, allowing attackers to gain root privileges on affected FreeBSD systems.
Likely Case
System crash or kernel panic resulting in denial of service, potentially requiring system reboot to restore functionality.
If Mitigated
Limited impact if IPv6 is disabled or systems are behind firewalls blocking ICMPv6 traffic from untrusted sources.
🎯 Exploit Status
Exploitation requires sending specially crafted ICMPv6 packets to vulnerable systems. No public exploit code has been disclosed.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: FreeBSD 12.2-STABLE r367402+, 11.4-STABLE r368202+, 12.2-RELEASE p1+, 12.1-RELEASE p11+, 11.4-RELEASE p5+
Vendor Advisory: https://security.FreeBSD.org/advisories/FreeBSD-SA-20:31.icmp6.asc
Restart Required: Yes
Instructions:
1. Update FreeBSD using 'freebsd-update fetch' and 'freebsd-update install' 2. Rebuild kernel from source if using custom kernel 3. Reboot system to load patched kernel
🔧 Temporary Workarounds
Disable IPv6
allCompletely disable IPv6 networking to prevent exploitation
sysrc ipv6_activate_all_interfaces="NO"
sysrc ipv6_enable="NO"
reboot
Block ICMPv6 traffic
allUse firewall rules to block incoming ICMPv6 packets
ip6fw add deny icmp6 from any to any
🧯 If You Can't Patch
- Implement strict firewall rules to block all ICMPv6 traffic from untrusted networks
- Consider disabling IPv6 entirely if not required for business operations
🔍 How to Verify
Check if Vulnerable:
Check FreeBSD version with 'uname -a' and compare against affected versions. Verify IPv6 is enabled with 'ifconfig -a | grep inet6'Check Version:
uname -aVerify Fix Applied:
After patching, verify version is updated and system has been rebooted. Check kernel version matches patched release.📡 Detection & Monitoring
Log Indicators:
- Kernel panic logs
- System crash dumps
- Network interface errors
Network Indicators:
- Unusual ICMPv6 traffic patterns
- Malformed ICMPv6 packets
SIEM Query:
source="freebsd" AND ("kernel panic" OR "icmp6" OR "use-after-free")