CVE-2024-49123: Windows 10 1809 RCE Vulnerability

CVE-2024-49123 Overview

CVE-2024-49123 is a Remote Code Execution vulnerability affecting Windows Remote Desktop Services (RDS). This vulnerability allows an unauthenticated attacker to execute arbitrary code on affected Windows systems by exploiting a race condition in the Remote Desktop Services component. The vulnerability is classified as CWE-362 (Concurrent Execution using Shared Resource with Improper Synchronization) and CWE-591 (Sensitive Data Storage in Improperly Locked Memory).

Critical Impact

Successful exploitation allows remote attackers to execute arbitrary code with no user interaction required, potentially leading to complete system compromise across enterprise environments using Remote Desktop Services.

Affected Products

• Microsoft Windows 10 1809 (x64 and x86)
• Microsoft Windows 10 21H2
• Microsoft Windows 10 22H2
• Microsoft Windows 11 22H2
• Microsoft Windows 11 23H2
• Microsoft Windows 11 24H2
• Microsoft Windows Server 2019
• Microsoft Windows Server 2022
• Microsoft Windows Server 2022 23H2
• Microsoft Windows Server 2025

Discovery Timeline

• December 12, 2024 - CVE-2024-49123 published to NVD
• January 14, 2025 - Last updated in NVD database

Technical Details for CVE-2024-49123

Vulnerability Analysis

This vulnerability exists within the Windows Remote Desktop Services component, which handles remote desktop protocol (RDP) connections. The root cause involves a race condition (CWE-362) that occurs during concurrent execution using shared resources with improper synchronization, combined with sensitive data storage in improperly locked memory (CWE-591).

The vulnerability requires a network-based attack vector but has high attack complexity, meaning exploitation is not trivial and requires specific conditions to be met. However, once these conditions are achieved, an attacker can gain complete control over the confidentiality, integrity, and availability of the target system without requiring any privileges or user interaction.

Root Cause

The vulnerability stems from two interconnected weaknesses in the Remote Desktop Services implementation:

1. Race Condition (CWE-362): The RDS component improperly synchronizes concurrent access to shared resources during session handling. This creates a time-of-check to time-of-use window that can be exploited.

2. Improper Memory Locking (CWE-591): Sensitive data stored in memory is not properly locked, allowing potential manipulation during the race condition window.

The combination of these weaknesses enables an attacker to manipulate memory states during RDP session establishment, potentially redirecting execution flow to attacker-controlled code.

Attack Vector

The attack is network-based and targets systems with Remote Desktop Services enabled. An attacker must:

1. Establish a connection to the target RDP service on TCP port 3389 (or the configured RDP port)
2. Send specially crafted RDP packets designed to trigger the race condition
3. Time the exploit to manipulate memory during the synchronization gap
4. Achieve code execution in the context of the RDS service

The high complexity rating indicates that successful exploitation requires precise timing and may not be reliable on the first attempt. However, once exploited, the attacker gains complete system access without authentication.

Due to the nature of this vulnerability, no verified proof-of-concept code is publicly available. The exploitation mechanism involves precise timing attacks against the RDP protocol session handling routines. Organizations should refer to the Microsoft Security Advisory for detailed technical guidance.

Detection Methods for CVE-2024-49123

Indicators of Compromise

• Unusual crash events in svchost.exe processes hosting Remote Desktop Services
• Abnormal memory allocation patterns in termservice (Terminal Services) logs
• Unexpected RDP session establishments from unknown or suspicious IP addresses
• System instability or crashes on RDP-enabled servers during connection attempts

Detection Strategies

• Monitor Windows Event Logs for Event ID 4625 (failed logon attempts) combined with subsequent RDP service anomalies
• Implement network-level detection for malformed or unusual RDP handshake sequences
• Deploy endpoint detection rules to identify exploitation attempts targeting the termsrv.dll component
• Configure SIEM alerts for rapid successive RDP connection attempts that may indicate race condition exploitation

Monitoring Recommendations

• Enable detailed auditing for Remote Desktop Services connections via Windows Security policies
• Implement network flow analysis on TCP port 3389 to detect anomalous traffic patterns
• Configure SentinelOne Singularity Platform to monitor for behavioral indicators associated with RDP exploitation
• Establish baseline RDP connection metrics to identify deviation indicating potential exploitation attempts

How to Mitigate CVE-2024-49123

Immediate Actions Required

• Apply Microsoft's security update immediately on all affected Windows systems
• Restrict RDP access using Network Level Authentication (NLA) as an additional defense layer
• Implement firewall rules to limit RDP access to trusted IP ranges only
• Consider disabling Remote Desktop Services on systems where it is not required
• Segment networks to isolate RDP-enabled systems from critical infrastructure

Patch Information

Microsoft has released security updates to address CVE-2024-49123 as part of their December 2024 security update cycle. Organizations should obtain and apply the appropriate patches from the Microsoft Security Update Guide.

Patches are available for:

• Windows 10 versions 1809, 21H2, and 22H2
• Windows 11 versions 22H2, 23H2, and 24H2
• Windows Server 2019, 2022, 2022 23H2, and 2025

Workarounds

• Disable Remote Desktop Services entirely if not required for business operations
• Enable Network Level Authentication (NLA) to add a pre-authentication layer
• Deploy a VPN or Remote Desktop Gateway to prevent direct RDP exposure to untrusted networks
• Implement IP-based access controls via Windows Firewall or network security appliances

# Disable Remote Desktop Services (if not needed)
Set-ItemProperty -Path 'HKLM:\System\CurrentControlSet\Control\Terminal Server' -Name "fDenyTSConnections" -Value 1

# Enable Network Level Authentication
Set-ItemProperty -Path 'HKLM:\System\CurrentControlSet\Control\Terminal Server\WinStations\RDP-Tcp' -Name "UserAuthentication" -Value 1

# Restrict RDP access via Windows Firewall (example: allow only from trusted subnet)
New-NetFirewallRule -DisplayName "Restrict RDP Access" -Direction Inbound -Protocol TCP -LocalPort 3389 -RemoteAddress 10.0.0.0/8 -Action Allow