CVE-2021-31853
📋 TL;DR
This vulnerability allows local users to execute arbitrary code with elevated privileges by placing a malicious DLL in a folder that McAfee Drive Encryption searches before legitimate system directories. It affects users of McAfee Drive Encryption versions prior to 7.3.0 HF2 (7.3.0.183).
💻 Affected Systems
- McAfee Drive Encryption
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Full system compromise with SYSTEM/administrator privileges, enabling complete control over the affected system, data theft, and lateral movement.
Likely Case
Local privilege escalation allowing attackers to gain administrative rights on the compromised system, potentially leading to persistence mechanisms and credential harvesting.
If Mitigated
Limited impact if proper application whitelisting, DLL search path restrictions, and least privilege principles are enforced.
🎯 Exploit Status
Requires local access to place malicious DLL in specific folder. DLL hijacking is a well-known technique with many existing tools and methods.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 7.3.0 HF2 (7.3.0.183) or later
Vendor Advisory: https://kc.mcafee.com/corporate/index?page=content&id=SB10374
Restart Required: Yes
Instructions:
1. Download the latest version from McAfee ePO or official website. 2. Install the update (7.3.0 HF2 or later). 3. Restart the system to complete installation.
🔧 Temporary Workarounds
Restrict DLL search paths
windowsConfigure Windows to restrict DLL search paths using Group Policy or registry settings to prevent loading from current directory.
reg add "HKLM\SYSTEM\CurrentControlSet\Control\Session Manager" /v "SafeDllSearchMode" /t REG_DWORD /d 1 /f
reg add "HKLM\SYSTEM\CurrentControlSet\Control\Session Manager" /v "CWDIllegalInDllSearch" /t REG_DWORD /d 0xffffffff /f
Application control policies
windowsImplement application whitelisting to prevent execution of unauthorized DLLs.
🧯 If You Can't Patch
- Implement least privilege principles - ensure users don't have write access to application directories
- Monitor for suspicious DLL loading events and file creation in application directories
🔍 How to Verify
Check if Vulnerable:
Check McAfee Drive Encryption version in Control Panel > Programs and Features or via command: wmic product where "name like 'McAfee Drive Encryption%'" get versionCheck Version:
wmic product where "name like 'McAfee Drive Encryption%'" get versionVerify Fix Applied:
Verify version is 7.3.0.183 or higher using the same command, and check that no unauthorized DLLs exist in application directories.📡 Detection & Monitoring
Log Indicators:
- Windows Event Logs: Process creation events for suspicious DLL loading
- Application logs showing DLL loading failures or unexpected DLL paths
Network Indicators:
- No direct network indicators - this is a local attack
SIEM Query:
EventID=4688 AND (NewProcessName contains ".dll" OR CommandLine contains ".dll") AND (ImagePath contains "McAfee" OR ParentProcessName contains "McAfee")