CVE-2022-41057 is a security vulnerability in the Windows HTTP.sys driver, patched by Microsoft in November 2022. This vulnerability allows attackers to gain higher privileges on a vulnerable Windows system. In this post, we’ll break down what CVE-2022-41057 is, how it can be exploited, and what you need to do to protect your systems.

We’ll keep things simple and practical, and if you’re a sysadmin or a security enthusiast, this is for you.

What is HTTP.sys?

HTTP.sys is the Windows HTTP protocol stack. It allows Windows to process HTTP requests. For example, IIS (Internet Information Services) relies on HTTP.sys to listen on port 80 and 443.

If there’s a bug in HTTP.sys, it could impact everything on the system that uses it — web servers, services, and sometimes even internal system functions.

About CVE-2022-41057

CVE-2022-41057 is an elevation of privilege (EoP) vulnerability. It means a lower-privileged attacker (like a web user, or a process) could trick HTTP.sys into letting them execute code or actions as a SYSTEM-level user.

Microsoft Advisory

- Official Security Update: Microsoft Security Guide

How Attackers Can Exploit CVE-2022-41057

Warning: This information is for educational purposes only! Don’t use it to attack systems you don’t own.

In vulnerable Windows systems, an attacker could send a specially-crafted HTTP request to HTTP.sys. If this request triggers the flaw, it may crash the driver or — much worse — allow running malicious code as SYSTEM.

Attack Scenario

1. The attacker sends a malformed or specially-structured HTTP request to a Windows server running HTTP.sys (that’s IIS by default, but other software may use it too).

The faulty HTTP.sys driver mishandles the request.

3. This could give the attacker the ability to escalate from a normal user (or even just network access) to full SYSTEM rights.

Example Exploit Snippet

The real exploit for this vulnerability is not publicly disclosed by Microsoft or official channels, but security researchers sometimes publish “proof of concept” (PoC) code. Below is a *conceptual* example that demonstrates how an attacker might send a request designed to exploit HTTP.sys.

Python Code Concept

import socket

def send_malicious_request():
    # Change HOST and PORT as appropriate
    HOST = "target-windows-server-ip"
    PORT = 80
    
    # This is a placeholder example; the actual malicious payload is based on the vulnerability details
    malicious_payload = (
        "GET / HTTP/1.1\r\n"
        "Host: vulnerable-server\r\n"
        "Custom-Header: A" * 700 + "\r\n"
        "\r\n"
    )

    with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
        s.connect((HOST, PORT))
        s.sendall(malicious_payload.encode())
        response = s.recv(4096)
        print(response.decode(errors='ignore'))

if __name__ == '__main__':
    send_malicious_request()

*Note: The actual exploit payload for CVE-2022-41057 is not released, and sending random long header fields probably won’t exploit this bug — but attackers would adapt something similar based on the security advisory specifics.*

Mitigation and Fix

Thankfully, Microsoft released a patch in November 2022. To check your patch levels:

Open Windows Update and install all security updates from November 2022 and later.

2. You can also manually download the update for your version of Windows.

There are no known workarounds if you can't patch — you must update your system.

Detection

Look for unusual crashes involving HTTP.sys in your Windows Event Logs, or unexplained SYSTEM-level privilege escalations on web servers. You can also use tools like Sysmon to monitor privileged process creation.

Resources & References

- Microsoft Update Guide: CVE-2022-41057
- NVD Entry for CVE-2022-41057
- Security Content Blog

Monitor for signs of abnormal HTTP.sys crashes or SYSTEM-level activity.

*Stay safe, keep your servers up-to-date, and always monitor security bulletins from trusted sources!*

Timeline

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