CVE-2020-14351
📋 TL;DR
CVE-2020-14351 is a use-after-free vulnerability in the Linux kernel's perf subsystem that allows local attackers with permission to monitor performance events to corrupt memory. This can lead to privilege escalation, compromising data confidentiality, integrity, and system availability. Affected systems include Linux distributions with vulnerable kernel versions.
💻 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
Local privilege escalation to root, complete system compromise, data theft, and persistent backdoor installation.
Likely Case
Local privilege escalation by authenticated users, potentially leading to lateral movement within the network.
If Mitigated
Limited to denial-of-service if proper access controls restrict perf event monitoring to trusted users only.
🎯 Exploit Status
Exploitation requires local access and perf event monitoring permissions; proof-of-concept code has been published.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Varies by distribution (e.g., kernel 5.8+ or backported patches in stable branches like 4.19.x, 5.4.x)
Vendor Advisory: https://bugzilla.redhat.com/show_bug.cgi?id=1862849
Restart Required: Yes
Instructions:
1. Update kernel package via distribution's package manager (e.g., 'yum update kernel' for RHEL, 'apt update && apt upgrade linux-image' for Debian/Ubuntu). 2. Reboot system to load new kernel.
🔧 Temporary Workarounds
Restrict perf event monitoring
linuxLimit access to perf subsystem by removing CAP_SYS_ADMIN from non-privileged users or using kernel.perf_event_paranoid sysctl.
sysctl -w kernel.perf_event_paranoid=3
🧯 If You Can't Patch
- Apply workaround to restrict perf event monitoring via sysctl or capability removal.
- Implement strict access controls to limit local user privileges and monitor for suspicious activity.
🔍 How to Verify
Check if Vulnerable:
Check kernel version and compare with patched versions for your distribution; e.g., 'uname -r' and consult vendor advisories.Check Version:
uname -rVerify Fix Applied:
Verify kernel version after update and reboot matches patched version; check that perf_event_paranoid is set appropriately if using workaround.📡 Detection & Monitoring
Log Indicators:
- Kernel logs (dmesg) showing crashes or corruption in perf subsystem
- Audit logs for unauthorized perf event access attempts
Network Indicators:
- Not applicable - local exploit only
SIEM Query:
Example: search for 'perf' events in kernel logs or auditd entries indicating privilege escalation attempts.🔗 References
- https://bugzilla.redhat.com/show_bug.cgi?id=1862849
- https://lists.debian.org/debian-lts-announce/2020/12/msg00015.html
- https://lists.debian.org/debian-lts-announce/2020/12/msg00027.html
- https://bugzilla.redhat.com/show_bug.cgi?id=1862849
- https://lists.debian.org/debian-lts-announce/2020/12/msg00015.html
- https://lists.debian.org/debian-lts-announce/2020/12/msg00027.html
