CVE-2023-52676
📋 TL;DR
This CVE-2023-52676 is an integer overflow vulnerability in the Linux kernel's BPF verifier that could allow local attackers to bypass stack limit checks. It affects systems running vulnerable Linux kernel versions where BPF is enabled. The vulnerability could lead to privilege escalation or kernel crashes.
💻 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 →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 →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, kernel panic leading to denial of service, or arbitrary code execution in kernel context
Likely Case
Kernel crash/panic causing system instability or denial of service
If Mitigated
Limited impact due to BPF restrictions and need for local access
🎯 Exploit Status
Exploitation requires local access and knowledge of BPF programming. No public exploits known at this time.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Fixed in kernel commits: 1d38a9ee81570c4bd61f557832dead4d6f816760, ad140fc856f0b1d5e2215bcb6d0cc247a86805a2, e5ad9ecb84405637df82732ee02ad741a5f782a6
Vendor Advisory: https://git.kernel.org/stable/c/1d38a9ee81570c4bd61f557832dead4d6f816760
Restart Required: Yes
Instructions:
1. Update Linux kernel to version containing the fix commits. 2. Check your distribution's security advisories for specific patched versions. 3. Reboot system after kernel update.
🔧 Temporary Workarounds
Disable BPF subsystem
linuxDisable the BPF subsystem via kernel boot parameters to mitigate the vulnerability
Add 'bpf_jit_enable=0' and 'bpf_disabled=1' to kernel boot parameters in /etc/default/grub or bootloader config
Restrict BPF usage
linuxUse Linux capabilities or SELinux/AppArmor to restrict BPF usage to trusted processes
Use setcap to remove CAP_BPF from non-essential processes
Configure SELinux/AppArmor policies to deny bpf syscall
🧯 If You Can't Patch
- Implement strict access controls to limit local user access to systems
- Monitor for unusual BPF program loading or kernel module activity
🔍 How to Verify
Check if Vulnerable:
Check kernel version and compare with distribution's security advisory. Check if kernel includes the fix commits.Check Version:
uname -rVerify Fix Applied:
Verify kernel version after update matches patched version from vendor advisory. Check that fix commits are present in kernel source.📡 Detection & Monitoring
Log Indicators:
- Kernel oops/panic messages
- Audit logs showing BPF program loading failures
- System crash/reboot events
Network Indicators:
- Not applicable - local vulnerability
SIEM Query:
source="kernel" AND ("oops" OR "panic" OR "BPF")🔗 References
- https://git.kernel.org/stable/c/1d38a9ee81570c4bd61f557832dead4d6f816760
- https://git.kernel.org/stable/c/ad140fc856f0b1d5e2215bcb6d0cc247a86805a2
- https://git.kernel.org/stable/c/e5ad9ecb84405637df82732ee02ad741a5f782a6
- https://git.kernel.org/stable/c/1d38a9ee81570c4bd61f557832dead4d6f816760
- https://git.kernel.org/stable/c/ad140fc856f0b1d5e2215bcb6d0cc247a86805a2
- https://git.kernel.org/stable/c/e5ad9ecb84405637df82732ee02ad741a5f782a6
