CVE-2023-4622
📋 TL;DR
This CVE describes a use-after-free vulnerability in the Linux kernel's af_unix component that allows local attackers to escalate privileges. The race condition in unix_stream_sendpage() can be exploited to achieve kernel memory corruption. Any Linux system using affected kernel versions is vulnerable.
💻 Affected Systems
- Linux Kernel
📦 What is this software?
Linux Kernel by Linux
The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...
Learn more about Linux Kernel →⚠️ Risk & Real-World Impact
Worst Case
Full root privilege escalation leading to complete system compromise, data theft, and persistent backdoor installation.
Likely Case
Local privilege escalation from unprivileged user to root, enabling lateral movement and persistence.
If Mitigated
Limited impact if proper access controls restrict local user accounts and SELinux/AppArmor policies are enforced.
🎯 Exploit Status
Exploit requires local access and race condition triggering. Public exploit code exists in security advisories and repositories.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Kernel with commit 790c2f9d15b594350ae9bca7b236f2b1859de02c
Vendor Advisory: https://lists.debian.org/debian-lts-announce/2023/10/msg00027.html
Restart Required: Yes
Instructions:
1. Update kernel package via distribution's package manager. 2. For Debian: apt update && apt upgrade linux-image-*. 3. Reboot system to load new kernel.
🔧 Temporary Workarounds
Restrict local user access
linuxLimit local user accounts and implement strict access controls to reduce attack surface.
Enable kernel hardening features
linuxUse SELinux, AppArmor, or other mandatory access controls to limit privilege escalation impact.
setenforce 1
systemctl enable apparmor
🧯 If You Can't Patch
- Implement strict access controls and limit local user accounts
- Monitor for privilege escalation attempts and unusual root activity
🔍 How to Verify
Check if Vulnerable:
Check kernel version and if commit 790c2f9d15b594350ae9bca7b236f2b1859de02c is present: uname -r && git log --oneline | grep 790c2f9d15b594350ae9bca7b236f2b1859de02cCheck Version:
uname -rVerify Fix Applied:
Verify kernel version after update and confirm commit is present: uname -r📡 Detection & Monitoring
Log Indicators:
- Unexpected privilege escalation events
- Kernel panic or oops messages
- Unusual root user activity
Network Indicators:
- Local socket abuse patterns
SIEM Query:
source="kernel" AND ("use-after-free" OR "af_unix" OR "privilege escalation")🔗 References
- http://packetstormsecurity.com/files/175963/Kernel-Live-Patch-Security-Notice-LSN-0099-1.html
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=linux-6.1.y&id=790c2f9d15b594350ae9bca7b236f2b1859de02c
- https://kernel.dance/790c2f9d15b594350ae9bca7b236f2b1859de02c
- https://lists.debian.org/debian-lts-announce/2023/10/msg00027.html
- https://lists.debian.org/debian-lts-announce/2024/01/msg00004.html
- https://www.debian.org/security/2023/dsa-5492
- http://packetstormsecurity.com/files/175963/Kernel-Live-Patch-Security-Notice-LSN-0099-1.html
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=linux-6.1.y&id=790c2f9d15b594350ae9bca7b236f2b1859de02c
- https://kernel.dance/790c2f9d15b594350ae9bca7b236f2b1859de02c
- https://lists.debian.org/debian-lts-announce/2023/10/msg00027.html
- https://lists.debian.org/debian-lts-announce/2024/01/msg00004.html
- https://www.debian.org/security/2023/dsa-5492
