CVE-2021-23887
📋 TL;DR
This CVE describes a local privilege escalation vulnerability in McAfee DLP Endpoint for Windows. A low-privileged local attacker can write to arbitrary kernel addresses by manipulating suspended applications monitored by McAfee DLP's hdlphook driver. This affects Windows systems running McAfee DLP Endpoint versions prior to 11.6.100.
💻 Affected Systems
- McAfee Data Loss Prevention (DLP) Endpoint
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with kernel-level code execution, allowing attackers to bypass all security controls, install persistent malware, or access sensitive data.
Likely Case
Local privilege escalation from standard user to SYSTEM/administrator privileges, enabling lateral movement, credential theft, and persistence establishment.
If Mitigated
Limited impact if proper endpoint security controls, least privilege principles, and network segmentation are in place to contain local attacks.
🎯 Exploit Status
Requires local access and ability to launch/suspend processes; kernel memory manipulation adds complexity but follows known patterns.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 11.6.100 or later
Vendor Advisory: https://kc.mcafee.com/corporate/index?page=content&id=SB10354
Restart Required: Yes
Instructions:
1. Download McAfee DLP Endpoint version 11.6.100 or later from official McAfee sources. 2. Deploy through McAfee ePolicy Orchestrator or manual installation. 3. Restart affected Windows systems to load patched driver.
🔧 Temporary Workarounds
Disable DLP Monitoring
windowsTemporarily disable McAfee DLP monitoring to prevent hdlphook driver exploitation.
Use McAfee ePolicy Orchestrator to disable DLP policies
Stop McAfee DLP services via services.msc
Restrict Local Access
windowsImplement strict local access controls and least privilege to limit attack surface.
Configure Windows Group Policy to restrict local user privileges
Implement application whitelisting
🧯 If You Can't Patch
- Implement strict network segmentation to isolate vulnerable systems and prevent lateral movement.
- Deploy additional endpoint detection and response (EDR) solutions to monitor for privilege escalation attempts.
🔍 How to Verify
Check if Vulnerable:
Check McAfee DLP Endpoint version in Control Panel > Programs and Features or via 'mcafee dlp' command line tools.Check Version:
wmic product where "name like 'McAfee Data Loss Prevention%'" get versionVerify Fix Applied:
Verify version is 11.6.100 or higher and check that hdlphook.sys driver date is updated post-patch.📡 Detection & Monitoring
Log Indicators:
- Unusual process suspension/modification events in Windows Event Logs
- McAfee DLP driver loading errors or crashes
Network Indicators:
- Unusual outbound connections from previously low-privileged accounts post-exploitation
SIEM Query:
EventID=4688 AND (ProcessName contains 'suspend' OR CommandLine contains 'debug') AND ParentProcessName contains 'explorer'