CVE-2023-23392: Windows 11 21h2 HTTP Stack RCE Flaw

CVE-2023-23392 Overview

CVE-2023-23392 is a critical remote code execution vulnerability in the HTTP Protocol Stack (http.sys) affecting Microsoft Windows 11 and Windows Server 2022 systems. This vulnerability allows unauthenticated remote attackers to execute arbitrary code on vulnerable systems by sending specially crafted HTTP requests to the target server.

Critical Impact

This vulnerability enables remote code execution without authentication, potentially allowing complete system compromise of Windows 11 and Windows Server 2022 systems running HTTP.sys-based services.

Affected Products

• Microsoft Windows 11 21H2
• Microsoft Windows 11 22H2
• Microsoft Windows Server 2022

Discovery Timeline

• 2023-03-14 - CVE-2023-23392 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2023-23392

Vulnerability Analysis

CVE-2023-23392 is a Use After Free (CWE-416) vulnerability in the Windows HTTP Protocol Stack (http.sys), a kernel-mode driver that processes HTTP requests. The vulnerability exists in the way http.sys handles certain HTTP/3 protocol operations. When processing specially crafted HTTP requests, the driver can access memory that has already been freed, leading to memory corruption and potential code execution in kernel context.

The vulnerability is particularly dangerous because http.sys is a kernel-mode component, meaning successful exploitation can result in code execution with SYSTEM privileges. Additionally, the attack requires no authentication and can be triggered remotely over the network, making it a prime target for mass exploitation.

Root Cause

The vulnerability stems from improper memory management within the HTTP Protocol Stack when handling HTTP/3 requests. Specifically, a Use After Free condition occurs when the driver references memory that has been previously deallocated. This can happen during the processing of HTTP/3 QUIC protocol operations where object lifetimes are not properly tracked, leading to a dangling pointer that can be leveraged for code execution.

Attack Vector

The attack vector is network-based, requiring no authentication or user interaction. An attacker can exploit this vulnerability by:

1. Identifying a vulnerable Windows 11 or Windows Server 2022 system with HTTP.sys exposed to the network
2. Crafting malicious HTTP/3 requests designed to trigger the Use After Free condition
3. Sending these requests to the target system's HTTP service
4. Achieving arbitrary code execution in kernel mode upon successful exploitation

The vulnerability specifically requires that HTTP/3 is enabled on the target system, which includes the buffered I/O feature. Systems without HTTP/3 enabled are not vulnerable to this specific attack.

Detection Methods for CVE-2023-23392

Indicators of Compromise

• Unexpected HTTP.sys driver crashes or Blue Screen of Death (BSOD) events on Windows 11 or Server 2022 systems
• Abnormal kernel memory access patterns associated with http.sys processes
• Unusual HTTP/3 traffic patterns targeting systems running IIS or other HTTP.sys-based services
• System event logs showing kernel-mode exceptions in HTTP.sys

Detection Strategies

• Monitor Windows Event Logs for HTTP.sys-related crashes or exceptions (Event IDs related to kernel driver failures)
• Deploy network intrusion detection rules to identify malformed HTTP/3 requests targeting Windows systems
• Implement endpoint detection to monitor for suspicious kernel memory operations associated with http.sys
• Use SentinelOne's behavioral AI engine to detect exploitation attempts targeting kernel-mode drivers

Monitoring Recommendations

• Enable detailed logging for IIS and HTTP.sys components to capture anomalous request patterns
• Monitor systems for unexpected SYSTEM-level process creation following HTTP traffic
• Implement network segmentation to limit exposure of HTTP.sys-based services
• Deploy SentinelOne agents on all Windows 11 and Server 2022 systems to provide real-time threat detection and response

How to Mitigate CVE-2023-23392

Immediate Actions Required

• Apply the Microsoft security update released in March 2023 Patch Tuesday immediately
• If patching is not immediately possible, disable HTTP/3 support on affected systems as a temporary workaround
• Review and restrict network access to HTTP.sys-based services to trusted networks only
• Ensure SentinelOne protection is enabled and policies are configured for maximum protection

Patch Information

Microsoft has released security updates to address CVE-2023-23392 as part of the March 2023 Patch Tuesday release. Administrators should apply the appropriate security update for their specific Windows version immediately. For detailed patch information and download links, refer to the Microsoft Security Response Center advisory.

Workarounds

• Disable HTTP/3 support via the registry by setting the EnableHttp3 DWORD value to 0 under HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\HTTP\Parameters
• Disable the HTTP/3 feature through Group Policy on enterprise systems until patches can be applied
• Restrict network access to systems running HTTP.sys services using firewall rules to limit exposure
• Consider disabling QUIC protocol support at the network perimeter as an additional protective measure

# Disable HTTP/3 on Windows via PowerShell (requires restart)
Set-ItemProperty -Path "HKLM:\System\CurrentControlSet\Services\HTTP\Parameters" -Name "EnableHttp3" -Value 0 -Type DWord

# Verify the setting was applied
Get-ItemProperty -Path "HKLM:\System\CurrentControlSet\Services\HTTP\Parameters" -Name "EnableHttp3"

# Restart the HTTP service to apply changes
Restart-Service -Name "HTTP" -Force