CVE-2022-35820: Windows 10 Bluetooth Privilege Escalation

CVE-2022-35820 Overview

CVE-2022-35820 is a Windows Bluetooth Driver Elevation of Privilege vulnerability affecting a wide range of Microsoft Windows operating systems. This driver vulnerability allows a local attacker with low privileges to escalate their access to gain high-level permissions on the affected system. The vulnerability exists within the Windows Bluetooth driver stack, which is a critical system component responsible for managing Bluetooth hardware communications.

Critical Impact

Successful exploitation allows a local attacker to escalate privileges from a low-privilege user to SYSTEM-level access, potentially enabling complete system compromise including data theft, malware installation, and lateral movement within enterprise networks.

Affected Products

• Microsoft Windows 10 (multiple versions including 1607, 1809, 20H2, 21H1, 21H2 on x86, x64, and ARM64 architectures)
• Microsoft Windows 11 (x64 and ARM64 architectures)
• Microsoft Windows 7 SP1 (x86 and x64)
• Microsoft Windows 8.1 (x86 and x64)
• Microsoft Windows RT 8.1
• Microsoft Windows Server 2008 R2 SP1
• Microsoft Windows Server 2012 and R2
• Microsoft Windows Server 2016 (including 20H2)
• Microsoft Windows Server 2019
• Microsoft Windows Server 2022

Discovery Timeline

• August 9, 2022 - CVE-2022-35820 published to NVD
• November 21, 2024 - Last updated in NVD database

Technical Details for CVE-2022-35820

Vulnerability Analysis

This elevation of privilege vulnerability resides in the Windows Bluetooth driver, a kernel-mode component that interfaces between the operating system and Bluetooth hardware. The vulnerability requires local access to the target system, meaning an attacker must already have the ability to execute code on the machine, albeit with limited privileges. Once exploited, the attacker can elevate their privileges to gain full control over the affected system.

The broad scope of affected products—spanning from Windows 7 through Windows 11 and corresponding Server editions—indicates that the vulnerable code has been present in the Windows Bluetooth driver stack for an extended period. This makes the vulnerability particularly concerning for enterprise environments running diverse Windows versions.

Root Cause

The root cause stems from improper handling within the Windows Bluetooth driver. While Microsoft has not disclosed specific technical details about the vulnerability mechanism, driver-level privilege escalation vulnerabilities typically arise from issues such as improper input validation, memory corruption, or insecure handling of user-supplied data in kernel mode. The Bluetooth driver operates at the kernel level, where any security flaw can have severe consequences for system integrity.

Attack Vector

The attack vector for CVE-2022-35820 is local, requiring an attacker to have authenticated access to the target system with low-level privileges. The exploitation path typically involves:

1. An attacker gains initial access to a Windows system through phishing, social engineering, or exploiting another vulnerability
2. The attacker executes a malicious application or script that interacts with the vulnerable Bluetooth driver
3. The driver improperly handles the malicious input, allowing the attacker to execute code in kernel mode
4. The attacker achieves SYSTEM-level privileges, gaining complete control over the affected machine

The vulnerability does not require user interaction beyond the attacker's initial code execution, and the attack complexity is considered low, making it a practical target for exploitation once initial access is obtained.

Detection Methods for CVE-2022-35820

Indicators of Compromise

• Suspicious processes or services interacting with Bluetooth driver components (bthport.sys, bthenum.sys, or related drivers)
• Unexpected privilege escalation events in Windows Security logs (Event ID 4672 - Special privileges assigned)
• Anomalous kernel-mode activity or driver loading behavior
• Processes running as SYSTEM that originated from low-privilege user contexts

Detection Strategies

• Monitor for unusual Bluetooth driver access patterns and IOCTL calls from non-standard processes
• Implement behavioral detection for privilege escalation attempts, particularly those involving driver interactions
• Use endpoint detection and response (EDR) solutions like SentinelOne to detect kernel-level exploitation attempts
• Enable Windows Defender Credential Guard and Virtualization-Based Security (VBS) to limit kernel attack surfaces

Monitoring Recommendations

• Enable detailed audit logging for process creation and privilege use (Windows Security Event IDs 4688, 4672)
• Configure SIEM rules to alert on suspicious privilege transitions from standard user accounts
• Monitor Bluetooth-related services and driver activity for anomalous behavior
• Regularly review Windows event logs for exploitation indicators

How to Mitigate CVE-2022-35820

Immediate Actions Required

• Apply the Microsoft security update for CVE-2022-35820 immediately on all affected Windows systems
• Prioritize patching systems with Bluetooth hardware enabled or in environments where local access is possible
• If patching cannot be performed immediately, disable Bluetooth functionality where not required
• Conduct an inventory of all Windows systems to identify affected versions

Patch Information

Microsoft released security updates addressing this vulnerability as part of their August 2022 Patch Tuesday release cycle. Administrators should apply the appropriate cumulative update for their Windows version through Windows Update, WSUS, or manual deployment. For detailed patch information and downloads, refer to the Microsoft Security Update Guide for CVE-2022-35820.

Workarounds

• Disable Bluetooth hardware through Device Manager or BIOS/UEFI settings on systems where Bluetooth is not required
• Implement application whitelisting to prevent unauthorized applications from running
• Apply the principle of least privilege to limit local user access rights
• Use network segmentation to limit lateral movement if a system is compromised

# PowerShell command to disable Bluetooth service
Stop-Service -Name "bthserv" -Force
Set-Service -Name "bthserv" -StartupType Disabled

# Verify Bluetooth service status
Get-Service -Name "bthserv" | Select-Object Name, Status, StartType