CVE-2023-21675: Windows 10 1607 Privilege Escalation Flaw

CVE-2023-21675 Overview

CVE-2023-21675 is a Windows Kernel Elevation of Privilege vulnerability that allows an attacker with local access and low-level privileges to escalate their permissions to gain complete control over the affected system. This vulnerability affects a wide range of Windows operating systems, including both client and server editions, making it a significant threat across enterprise environments.

The vulnerability exists within the Windows kernel and can be exploited by a local attacker to elevate privileges from a standard user account to SYSTEM-level access. This type of vulnerability is particularly dangerous in scenarios where an attacker has already gained initial access to a system through other means, such as phishing or other social engineering attacks.

Critical Impact

Successful exploitation enables complete system compromise through privilege escalation, allowing attackers to install programs, view/change/delete data, or create new accounts with full administrative rights.

Affected Products

• Microsoft Windows 10 (versions 1607, 1809, 20H2, 21H2, 22H2)
• Microsoft Windows 11 (versions 21H2, 22H2)
• Microsoft Windows 7 SP1
• Microsoft Windows 8.1 and Windows RT 8.1
• Microsoft Windows Server 2008 SP2 and R2 SP1
• Microsoft Windows Server 2012 and R2
• Microsoft Windows Server 2016, 2019, and 2022

Discovery Timeline

• January 10, 2023 - CVE-2023-21675 published to NVD
• November 21, 2024 - Last updated in NVD database

Technical Details for CVE-2023-21675

Vulnerability Analysis

This privilege escalation vulnerability resides in the Windows kernel and is classified under CWE-843 (Type Confusion). Type confusion vulnerabilities occur when a program allocates or initializes a resource using one type but later accesses that resource using an incompatible type. In kernel-level code, this can lead to memory corruption and arbitrary code execution with elevated privileges.

The vulnerability requires local access to exploit, meaning an attacker must first have the ability to execute code on the target system. Once local access is obtained, the attacker can leverage this vulnerability to escalate from a low-privileged user context to SYSTEM privileges without requiring any user interaction.

Root Cause

The root cause of CVE-2023-21675 is a type confusion flaw within the Windows kernel. The kernel improperly handles certain object types during processing, leading to a scenario where memory structures are accessed using incorrect type assumptions. This type confusion can result in memory corruption that an attacker can manipulate to gain elevated privileges.

Type confusion vulnerabilities in kernel code are particularly severe because the kernel operates at the highest privilege level. Any successful exploitation directly grants the attacker complete control over the operating system.

Attack Vector

The attack vector for CVE-2023-21675 is local, requiring the attacker to have authenticated access to the target system. The exploitation flow typically follows this pattern:

1. The attacker gains initial access to the system with low-privileged credentials
2. The attacker executes a specially crafted application or script that triggers the type confusion vulnerability in the kernel
3. The kernel processes the malformed input, causing improper type handling
4. The attacker leverages this memory corruption to execute arbitrary code in kernel mode
5. The attacker achieves SYSTEM-level privileges on the compromised host

This vulnerability does not require user interaction, making it particularly effective in post-exploitation scenarios where attackers seek to expand their access within a compromised environment.

Detection Methods for CVE-2023-21675

Indicators of Compromise

• Unexpected processes running with SYSTEM privileges that originated from low-privileged user sessions
• Anomalous kernel driver loading events or suspicious system calls
• Unusual privilege escalation patterns in Windows Security Event logs (Event IDs 4672, 4673, 4674)
• Suspicious process creation chains where child processes have higher privileges than parent processes

Detection Strategies

• Monitor for suspicious process privilege changes using endpoint detection and response (EDR) solutions
• Implement behavioral analysis rules to detect privilege escalation attempts targeting the Windows kernel
• Configure Windows Security Event logging to capture privilege use and process creation events
• Deploy SentinelOne Singularity platform for real-time kernel-level threat detection and prevention

Monitoring Recommendations

• Enable Windows Security Event Log auditing for sensitive privilege use and special logon events
• Implement centralized log collection and analysis for identifying privilege escalation patterns
• Deploy memory protection mechanisms that can detect and prevent kernel exploitation attempts
• Conduct regular vulnerability assessments to identify unpatched systems susceptible to CVE-2023-21675

How to Mitigate CVE-2023-21675

Immediate Actions Required

• Apply the January 2023 Microsoft security updates immediately to all affected Windows systems
• Prioritize patching for internet-facing servers and systems with sensitive data
• Implement application whitelisting to prevent unauthorized code execution
• Review user account privileges and enforce the principle of least privilege

Patch Information

Microsoft has released security updates addressing CVE-2023-21675 as part of the January 2023 Patch Tuesday release cycle. Organizations should apply the relevant updates based on their Windows version:

For detailed patch information and download links, refer to the Microsoft Security Update Guide for CVE-2023-21675.

The patches address the underlying type confusion vulnerability in the Windows kernel by implementing proper type validation and memory handling during object processing.

Workarounds

• Restrict local access to systems by enforcing strong authentication and access controls
• Implement network segmentation to limit lateral movement if a system is compromised
• Deploy endpoint protection solutions with behavioral analysis capabilities to detect exploitation attempts
• Monitor systems for signs of privilege escalation using security information and event management (SIEM) solutions

# Verify Windows Update status using PowerShell
Get-HotFix | Where-Object {$_.InstalledOn -gt (Get-Date).AddDays(-30)} | Select-Object HotFixID, InstalledOn

# Check for pending updates
Get-WindowsUpdate -AcceptAll -IgnoreReboot

# Enable enhanced logging for privilege use detection
auditpol /set /subcategory:"Sensitive Privilege Use" /success:enable /failure:enable