---

In this article, we’ll break down everything you need to know about CVE-2022-41058, a Windows Network Address Translation (NAT) vulnerability that could let an attacker bring your system down—no fully remote code execution, but still a real headache. This write-up covers how it works, how to protect yourself, code snippets, and all the official references you’ll want. Let’s get started!

What is CVE-2022-41058?

*CVE-2022-41058* is a security flaw found in the Windows NAT driver (specifically in the Windows Filtering Platform, or WFP). This bug can be abused to trigger a Denial of Service (DoS) condition. In plain English: a bad guy can cause your system, especially if it’s being used as a router or firewall with NAT, to crash or hang.

The Microsoft advisory describes it this way

> “A denial of service vulnerability exists when Windows Network Address Translation (NAT) improperly handles network packets. An attacker who successfully exploited the vulnerability could cause the target system to stop responding.”  
> — Microsoft CVE-2022-41058 reference

Who’s at Risk?

This CVE affects systems running Windows 10, Windows 11, and Windows Server editions that use the NAT feature, commonly present in Hyper-V virtual switches, RRAS (Routing and Remote Access Service), or similar setups.

Regular desktop users: Not likely affected unless you’ve set up NAT features.
 
Admins/IT pros: If you’re using Windows as a router/firewall or with Hyper-V NAT, watch out!

The Technical Details

The NAT driver in Windows mismanages certain network packet sequences. If an attacker crafts a special set of packets and sends them to the target machine’s public-facing interface, the NAT driver might mishandle these, causing a system crash (bluescreen) or making NAT/network services hang.

The vulnerability does not allow code execution or privilege escalation, but denial of service can be plenty damaging, especially in production environments.

Example Attack Scenario

Imagine you’re running a Windows Server as a firewall using RRAS and NAT. An attacker from the Internet or a local network could send malformed packets at your server. When these reach the NAT driver, the system might freeze or instantly reboot, dropping all connections.

Proof-of-Concept (PoC) Overview

While the original advisory didn’t ship PoC code, several security researchers have discussed approaches for triggering similar bugs. The gist: You can use tools like Scapy (Python) to craft packets, or hping3 on Linux.

Below is a *simple* Python snippet built with Scapy. This doesn't exploit the exact bug (it would be illegal to provide a working exploit!), but shows how such attacks can be staged.

from scapy.all import *
import random

# Replace with the target public IP of the NAT device
TARGET_IP = "192..2.1"
TARGET_PORT = 80

# Malformed packet generator
for i in range(100):  # Send lots of packets to trigger the flaw
    pkt = IP(dst=TARGET_IP)/TCP(dport=TARGET_PORT, flags="S", window=)
    send(pkt, verbose=)

Disclaimer: This will NOT trigger CVE-2022-41058 but gives you an idea of how someone might flood/abuse a NAT network interface with custom packets.

Microsoft released a fix in the December 2022 Patch Tuesday update.

See: Microsoft Security Update Guide - CVE-2022-41058

Original References & Further Reading

- Official Microsoft Advisory
- Microsoft Patch Tuesday December 2022 release notes
- Windows Filtering Platform documentation

Final Thoughts

*CVEs like 2022-41058 highlight how even simple bugs in network features can lead to big disruptions. While this is “only” a denial of service, that can still take down a network, virtual machines, or leave remote workers cut off!*

Protect yourself by patching and practicing least exposure—don’t leave NAT/routing services open wider than they have to be.

Stay safe, patch early!

*If you liked this breakdown, share it with your network admins. Questions? Drop them below!*

Timeline

Published on: 11/09/2022 22:15:00 UTC
Last modified on: 11/10/2022 00:33:00 UTC