CVE-2023-36423: Windows 10 1507 RCE Vulnerability

CVE-2023-36423 Overview

CVE-2023-36423 is a remote code execution vulnerability affecting the Microsoft Remote Registry Service across a wide range of Windows operating systems. This vulnerability allows an authenticated attacker with low privileges to execute arbitrary code on vulnerable systems by exploiting a heap-based buffer overflow (CWE-122) in the Remote Registry Service component.

The Remote Registry Service enables remote users to modify registry settings on target computers. When successfully exploited, this vulnerability could allow an attacker to execute code with elevated privileges, potentially leading to complete system compromise.

Critical Impact

Successful exploitation enables authenticated attackers to achieve remote code execution with the potential to fully compromise affected Windows systems, access sensitive data, and establish persistent access across enterprise environments.

Affected Products

• Microsoft Windows 10 (versions 1507, 1607, 1809, 21H2, 22H2)
• Microsoft Windows 11 (versions 21H2, 22H2, 23H2)
• Microsoft Windows Server 2008 (SP2, R2 SP1)
• Microsoft Windows Server 2012 and 2012 R2
• Microsoft Windows Server 2016
• Microsoft Windows Server 2019
• Microsoft Windows Server 2022
• Microsoft Windows Server 23H2

Discovery Timeline

• November 14, 2023 - CVE-2023-36423 published to NVD
• November 21, 2024 - Last updated in NVD database

Technical Details for CVE-2023-36423

Vulnerability Analysis

This vulnerability exists within the Remote Registry Service (regsvc.dll), a Windows component that allows authorized remote access to the Windows Registry. The flaw is classified as a heap-based buffer overflow (CWE-122), which occurs when the service improperly handles specially crafted registry requests.

When processing certain registry operations, the service fails to properly validate the size of input data before copying it into a fixed-size heap buffer. This boundary condition error allows an attacker who has authenticated to the system to send malicious requests that overflow the allocated buffer, potentially corrupting adjacent memory structures.

The vulnerability requires network access and low-privilege authentication, meaning an attacker must have valid credentials to the target system but does not require administrative access to trigger the vulnerability. The attack can be performed without user interaction, making it particularly dangerous in environments where the Remote Registry Service is enabled and exposed.

Root Cause

The root cause of CVE-2023-36423 is improper bounds checking within the Remote Registry Service when handling registry data operations. The heap-based buffer overflow occurs because the service allocates a fixed-size buffer for incoming data but fails to validate that the actual data length does not exceed this allocation before performing memory copy operations.

This type of vulnerability typically manifests in legacy code paths where size validation was either absent or insufficient. The Remote Registry Service, being a long-standing Windows component present since early versions, contains code that predates modern secure coding practices.

Attack Vector

The attack vector for this vulnerability is network-based, targeting systems where the Remote Registry Service is accessible. An attacker would follow this general exploitation approach:

1. Initial Access: The attacker must first obtain valid credentials for the target system, even with low-privilege access
2. Service Connection: Using the Remote Registry RPC interface, the attacker establishes a connection to the target's Remote Registry Service
3. Malicious Request: A specially crafted registry operation request containing oversized data is sent to the service
4. Buffer Overflow: The service processes the request without proper bounds checking, causing heap memory corruption
5. Code Execution: Through careful manipulation of the overflow, the attacker can overwrite critical memory structures and redirect execution to attacker-controlled code

The vulnerability does not require any user interaction and operates entirely at the network protocol level, making automated exploitation feasible once authentication is achieved.

Detection Methods for CVE-2023-36423

Indicators of Compromise

• Unusual network connections to TCP port 445 (SMB) or RPC dynamic ports targeting the Remote Registry Service
• Unexpected or anomalous registry access patterns from remote systems
• Process crashes or restarts of the svchost.exe process hosting the Remote Registry Service
• Memory access violations or heap corruption events logged in Windows Error Reporting

Detection Strategies

• Monitor Windows Event Logs for Security Event ID 4663 (attempted registry access) from unexpected remote sources
• Deploy network intrusion detection rules to identify malformed Remote Registry RPC traffic patterns
• Implement behavioral analysis to detect unusual registry modification attempts from low-privilege accounts
• Configure SentinelOne agents to monitor for heap corruption indicators and suspicious memory operations in regsvc.dll

Monitoring Recommendations

• Enable verbose logging for the Remote Registry Service and centralize logs for SIEM analysis
• Implement network segmentation to limit Remote Registry Service exposure to only authorized management systems
• Configure real-time alerting for any Remote Registry connections originating from unexpected network segments
• Deploy endpoint detection and response (EDR) solutions capable of monitoring RPC-based attacks

How to Mitigate CVE-2023-36423

Immediate Actions Required

• Apply the Microsoft security update released in November 2023 to all affected Windows systems immediately
• Disable the Remote Registry Service on systems where it is not required using sc config RemoteRegistry start= disabled
• Implement network-level access controls to restrict Remote Registry Service access to authorized management hosts only
• Audit current service configurations to identify systems with Remote Registry Service enabled

Patch Information

Microsoft has released security updates addressing CVE-2023-36423 as part of the November 2023 Patch Tuesday release cycle. Administrators should consult the Microsoft Security Update Guide for CVE-2023-36423 for detailed patch information specific to their Windows versions.

The security updates address the underlying heap-based buffer overflow by implementing proper input validation and bounds checking in the Remote Registry Service's data handling routines.

Workarounds

• Disable the Remote Registry Service entirely if not required for business operations
• Restrict network access to the Remote Registry Service using Windows Firewall rules or network firewalls
• Implement strong authentication and limit accounts with remote registry access privileges
• Consider using alternative remote management solutions that do not rely on the Remote Registry Service

# Disable Remote Registry Service on Windows
sc config RemoteRegistry start= disabled
sc stop RemoteRegistry

# Block Remote Registry access via Windows Firewall (PowerShell)
New-NetFirewallRule -DisplayName "Block Remote Registry" -Direction Inbound -Service RemoteRegistry -Action Block