CVE-2023-28232: Windows 10 1507 PPTP RCE Vulnerability

CVE-2023-28232 Overview

CVE-2023-28232 is a remote code execution vulnerability affecting the Windows Point-to-Point Tunneling Protocol (PPTP) implementation across a wide range of Microsoft Windows operating systems. This vulnerability allows an attacker to execute arbitrary code on affected systems through a network-based attack vector, though exploitation requires user interaction and involves high attack complexity due to an underlying race condition (CWE-362).

The PPTP protocol has historically been used for VPN connections and legacy network infrastructure. While modern deployments often favor more secure alternatives, PPTP remains enabled by default on many Windows systems, making this vulnerability particularly concerning for organizations with diverse Windows environments.

Critical Impact

Successful exploitation could allow an attacker to execute arbitrary code with elevated privileges on affected Windows systems, potentially leading to complete system compromise, data exfiltration, or lateral movement within enterprise networks.

Affected Products

• Microsoft Windows 10 (versions 1507, 1607, 1809, 20H2, 21H2, 22H2)
• Microsoft Windows 11 (versions 21H2, 22H2)
• Microsoft Windows Server 2008 (SP2 and R2 SP1)
• Microsoft Windows Server 2012 and Server 2012 R2
• Microsoft Windows Server 2016
• Microsoft Windows Server 2019
• Microsoft Windows Server 2022

Discovery Timeline

• April 11, 2023 - CVE-2023-28232 published to NVD
• November 21, 2024 - Last updated in NVD database

Technical Details for CVE-2023-28232

Vulnerability Analysis

This remote code execution vulnerability resides in the Windows Point-to-Point Tunneling Protocol implementation. The vulnerability stems from a race condition (CWE-362) that can be triggered during PPTP session handling. While the attack vector is network-based, successful exploitation requires specific conditions to be met: the attacker must win a race condition and the target user must be involved in the exploitation chain through some form of interaction.

The vulnerability affects the core PPTP protocol handler within Windows, which processes incoming tunnel connection requests and manages VPN session states. When a specially crafted PPTP packet sequence is received under specific timing conditions, the race condition can be triggered, potentially allowing memory corruption that leads to code execution.

Root Cause

The root cause of CVE-2023-28232 is a race condition (CWE-362) in the Windows PPTP implementation. Race conditions occur when the behavior of software depends on the relative timing of events, such as the order in which threads execute. In this case, the PPTP protocol handler fails to properly synchronize access to shared resources during tunnel session processing, creating a window where an attacker can manipulate memory state between the time a resource is checked and when it is used.

Attack Vector

The attack is network-based, requiring the attacker to send specially crafted PPTP packets to a vulnerable Windows system. The high attack complexity rating reflects the requirement to win a race condition, which typically requires precise timing and multiple exploitation attempts. Additionally, user interaction is required, suggesting the victim must take some action (such as initiating a PPTP connection or interacting with a malicious network resource) for the exploit to succeed.

An attacker would need to:

1. Position themselves to communicate with the target system via PPTP (TCP port 1723)
2. Send crafted PPTP control messages designed to trigger the race condition
3. Time the attack to exploit the synchronization flaw during session processing
4. Successfully corrupt memory to achieve code execution

Detection Methods for CVE-2023-28232

Indicators of Compromise

• Unusual PPTP traffic patterns on TCP port 1723, particularly repeated rapid connection attempts
• Crash dumps or unexpected system restarts in raspptp.sys or related PPTP driver components
• Anomalous process execution originating from PPTP-related system services
• Memory corruption signatures in Windows event logs associated with RAS services

Detection Strategies

• Monitor network traffic for abnormal PPTP control message sequences using network intrusion detection systems
• Deploy endpoint detection rules to identify exploitation attempts targeting PPTP services
• Configure Windows Event Log monitoring for RAS and VPN service anomalies
• Implement SentinelOne's behavioral AI to detect suspicious activity patterns indicative of race condition exploitation

Monitoring Recommendations

• Enable detailed logging for Windows Remote Access Services (RAS) and VPN components
• Configure SIEM alerts for multiple failed PPTP connection attempts from single sources
• Monitor for unexpected process spawning by svchost.exe instances associated with PPTP services
• Leverage SentinelOne Singularity platform for real-time endpoint visibility and automated threat detection

How to Mitigate CVE-2023-28232

Immediate Actions Required

• Apply the April 2023 Microsoft security updates immediately on all affected Windows systems
• Disable PPTP if it is not required for business operations
• Implement network segmentation to limit exposure of PPTP services
• Review and restrict inbound access to TCP port 1723 through firewall rules
• Deploy SentinelOne endpoint protection to detect and prevent exploitation attempts

Patch Information

Microsoft has released security updates addressing CVE-2023-28232 as part of the April 2023 Patch Tuesday release. Organizations should obtain the appropriate patches from the Microsoft Security Update Guide and apply them according to their patch management procedures. The patches address the underlying race condition in the PPTP implementation.

Workarounds

• Disable the PPTP protocol by stopping and disabling the Remote Access Connection Manager and Routing and Remote Access services if PPTP VPN functionality is not required
• Block inbound TCP port 1723 at the network perimeter to prevent external exploitation attempts
• Migrate legacy PPTP VPN connections to more secure alternatives such as IKEv2, L2TP/IPsec, or SSTP
• Implement network access controls to limit which systems can communicate via PPTP

# Disable PPTP-related services on Windows (PowerShell)
Stop-Service -Name "RasMan" -Force
Set-Service -Name "RasMan" -StartupType Disabled
Stop-Service -Name "RemoteAccess" -Force
Set-Service -Name "RemoteAccess" -StartupType Disabled

# Block PPTP port via Windows Firewall
New-NetFirewallRule -DisplayName "Block PPTP Inbound" -Direction Inbound -Protocol TCP -LocalPort 1723 -Action Block