CVE-2024-20692: Windows 10 Information Disclosure Flaw

CVE-2024-20692 Overview

CVE-2024-20692 is an information disclosure vulnerability affecting the Microsoft Local Security Authority Subsystem Service (LSASS), a critical Windows component responsible for enforcing security policies, handling user authentication, and managing access tokens. This vulnerability allows an authenticated attacker to potentially extract sensitive information from the LSASS process through inadequate cryptographic strength or exposure of resources to the wrong sphere.

Critical Impact

Successful exploitation could allow attackers to obtain sensitive authentication data including credentials, security tokens, or other confidential information processed by LSASS, potentially enabling lateral movement or privilege escalation within compromised environments.

Affected Products

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

Discovery Timeline

• January 9, 2024 - CVE-2024-20692 published to NVD
• November 21, 2024 - Last updated in NVD database

Technical Details for CVE-2024-20692

Vulnerability Analysis

This vulnerability in the Local Security Authority Subsystem Service (LSASS) is classified under CWE-326 (Inadequate Encryption Strength) and CWE-668 (Exposure of Resource to Wrong Sphere). LSASS is a fundamental Windows security component that handles authentication processes, password changes, access token generation, and security policy enforcement.

The vulnerability requires an authenticated user with network access to exploit. User interaction is required for successful exploitation, which limits the attack surface. The primary impact is on confidentiality, as the vulnerability allows unauthorized disclosure of sensitive information without affecting system integrity or availability.

The EPSS (Exploit Prediction Scoring System) indicates a 1.07% probability of exploitation, placing it in the 77th percentile, suggesting moderate likelihood of real-world exploitation attempts.

Root Cause

The root cause stems from two fundamental weaknesses in the LSASS implementation:

1. Inadequate Encryption Strength (CWE-326): The affected LSASS component utilizes cryptographic algorithms or key lengths that do not provide sufficient protection against modern attack techniques, potentially allowing sensitive data to be decrypted or recovered by attackers.

2. Exposure of Resource to Wrong Sphere (CWE-668): The product exposes a resource to actors in the wrong control sphere, providing unintended access to sensitive information that should be protected within the LSASS security boundary.

Attack Vector

The attack requires network access and authenticated credentials on the target system. The attacker must also trick a user into performing specific actions (user interaction required) to trigger the information disclosure condition.

The exploitation scenario involves an authenticated attacker leveraging weaknesses in LSASS data handling to access confidential information that traverses or is stored within the LSASS process. Due to the nature of LSASS handling authentication data including password hashes, Kerberos tickets, and NTLM credentials, successful exploitation could expose highly sensitive authentication material.

This vulnerability does not currently have known public exploits or proof-of-concept code available. The attack complexity is considered low once the prerequisite conditions (authenticated access and user interaction) are met.

Detection Methods for CVE-2024-20692

Indicators of Compromise

• Unusual process access attempts targeting lsass.exe from non-standard processes or user contexts
• Anomalous authentication patterns or credential access attempts correlating with suspicious user activity
• Unexpected memory read operations against the LSASS process space
• Security event logs showing repeated authentication or credential enumeration activities from single accounts

Detection Strategies

• Enable and monitor Windows Security Event logs for Event IDs related to credential access and LSASS operations (Event ID 4624, 4625, 4648, 4768, 4769)
• Deploy endpoint detection rules to identify processes attempting to read LSASS memory outside normal system operations
• Implement behavioral analytics to detect anomalous patterns in authentication data access
• Configure Windows Defender Credential Guard alerts for attempted credential theft activities

Monitoring Recommendations

• Enable Protected Process Light (PPL) for LSASS to detect and prevent unauthorized memory access attempts
• Configure Windows Defender ATP or SentinelOne Singularity to monitor for LSASS manipulation techniques
• Implement audit policies for detailed security event logging around credential management and authentication events
• Establish baselines for normal LSASS activity to facilitate anomaly detection

How to Mitigate CVE-2024-20692

Immediate Actions Required

• Apply the January 2024 Microsoft security updates immediately to all affected Windows systems
• Prioritize patching domain controllers and other critical authentication infrastructure
• Enable Windows Defender Credential Guard on supported systems to add additional protection for credentials stored in LSASS
• Review and restrict network access to sensitive systems to minimize exposure

Patch Information

Microsoft has released security updates addressing this vulnerability as part of the January 2024 Patch Tuesday release cycle. Detailed patch information and download links are available in the Microsoft Security Update Guide for CVE-2024-20692.

Organizations should deploy updates using their standard patch management processes, prioritizing:

• Domain Controllers
• Authentication servers
• Systems handling sensitive data
• Externally accessible systems

Workarounds

• Enable Windows Defender Credential Guard on Windows 10 Enterprise and Windows Server 2016+ to isolate LSASS and protect credentials in a virtualization-based security container
• Implement network segmentation to limit lateral movement capabilities if credential theft occurs
• Enable Protected Process Light (PPL) for LSASS by setting the RunAsPPL registry value to prevent unauthorized access to the LSASS process
• Limit the number of users with local administrator privileges to reduce the attack surface

# Enable LSASS Protected Process Light (PPL) via Registry
reg add "HKLM\SYSTEM\CurrentControlSet\Control\Lsa" /v RunAsPPL /t REG_DWORD /d 1 /f

# Verify Credential Guard status (PowerShell)
Get-CimInstance -ClassName Win32_DeviceGuard -Namespace root\Microsoft\Windows\DeviceGuard