CVE-2022-25636
📋 TL;DR
CVE-2022-25636 is a heap out-of-bounds write vulnerability in the Linux kernel's netfilter component that allows local users to escalate privileges to root. The vulnerability affects Linux kernel versions 5.4 through 5.6.10 and requires local access to exploit.
💻 Affected Systems
- Linux Kernel
📦 What is this software?
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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 →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 attacker gains full root privileges, enabling complete system compromise, data theft, persistence establishment, and lateral movement.
Likely Case
Local user or compromised service account escalates to root privileges, allowing installation of malware, credential harvesting, and system manipulation.
If Mitigated
With proper access controls and minimal local user accounts, impact is limited to already-privileged users or services.
🎯 Exploit Status
Public exploit code available, requires local user access but exploitation is straightforward once local access is obtained.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Linux kernel 5.6.11 and later, or backported patches for earlier versions
Vendor Advisory: https://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf.git/commit/?id=b1a5983f56e371046dcf164f90bfaf704d2b89f6
Restart Required: Yes
Instructions:
1. Update kernel to version 5.6.11 or later. 2. For distributions with backported patches, apply security updates via package manager. 3. Reboot system to load patched kernel.
🔧 Temporary Workarounds
Disable nf_tables offload
linuxPrevents exploitation by disabling the vulnerable nf_tables offload functionality
echo 0 > /proc/sys/net/netfilter/nf_tables_offload
Restrict local user access
allLimit number of local user accounts and implement strict access controls
🧯 If You Can't Patch
- Implement strict access controls to limit local user accounts
- Monitor for privilege escalation attempts and unusual root activity
🔍 How to Verify
Check if Vulnerable:
Check kernel version with 'uname -r' and verify if between 5.4 and 5.6.10 inclusiveCheck Version:
uname -rVerify Fix Applied:
Verify kernel version is 5.6.11 or later, or check with distribution-specific security update verification📡 Detection & Monitoring
Log Indicators:
- Unexpected privilege escalation events
- Kernel panic or crash logs related to netfilter
- Failed attempts to load kernel modules
Network Indicators:
- Unusual outbound connections from system after local user activity
SIEM Query:
source="kernel" AND ("nf_dup_netdev" OR "nf_tables_offload" OR "privilege escalation")🔗 References
- http://packetstormsecurity.com/files/166444/Kernel-Live-Patch-Security-Notice-LSN-0085-1.html
- http://www.openwall.com/lists/oss-security/2022/02/22/1
- https://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf.git/commit/?id=b1a5983f56e371046dcf164f90bfaf704d2b89f6
- https://github.com/Bonfee/CVE-2022-25636
- https://nickgregory.me/linux/security/2022/03/12/cve-2022-25636/
- https://security.netapp.com/advisory/ntap-20220325-0002/
- https://www.debian.org/security/2022/dsa-5095
- https://www.openwall.com/lists/oss-security/2022/02/21/2
- https://www.oracle.com/security-alerts/cpujul2022.html
- http://packetstormsecurity.com/files/166444/Kernel-Live-Patch-Security-Notice-LSN-0085-1.html
- http://www.openwall.com/lists/oss-security/2022/02/22/1
- https://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf.git/commit/?id=b1a5983f56e371046dcf164f90bfaf704d2b89f6
- https://github.com/Bonfee/CVE-2022-25636
- https://nickgregory.me/linux/security/2022/03/12/cve-2022-25636/
- https://security.netapp.com/advisory/ntap-20220325-0002/
- https://www.debian.org/security/2022/dsa-5095
- https://www.openwall.com/lists/oss-security/2022/02/21/2
- https://www.oracle.com/security-alerts/cpujul2022.html
