CVE-2021-31838
📋 TL;DR
This vulnerability allows authenticated MVISION EDR administrators to execute arbitrary PowerShell commands on client systems through the 'execute reaction' functionality. Attackers with administrative access can achieve remote code execution on managed endpoints. Only MVISION EDR deployments with vulnerable versions are affected.
💻 Affected Systems
- McAfee MVISION Endpoint Detection and Response (MVEDR)
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of all managed endpoints, allowing attackers to deploy ransomware, steal sensitive data, or establish persistent backdoors across the entire environment.
Likely Case
Privileged attacker uses legitimate admin credentials to execute malicious commands on specific high-value targets, potentially leading to data exfiltration or lateral movement.
If Mitigated
With proper access controls and monitoring, exploitation would be detected quickly and limited to specific systems before containment.
🎯 Exploit Status
Exploitation requires administrative credentials but is straightforward once access is obtained. The vulnerability is in a legitimate administrative function.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 3.4.0 and later
Vendor Advisory: https://kc.mcafee.com/corporate/index?page=content&id=SB10342
Restart Required: Yes
Instructions:
1. Download MVISION EDR version 3.4.0 or later from the McAfee support portal. 2. Deploy the update to the MVISION EDR server. 3. Restart the MVISION EDR service. 4. Ensure all managed endpoints receive updated client components.
🔧 Temporary Workarounds
Restrict Administrative Access
allLimit MVISION EDR administrative accounts to only trusted personnel and implement multi-factor authentication.
Disable PowerShell on Non-Essential Systems
windowsRemove or restrict PowerShell execution on endpoints where it's not required for operations.
Set-ExecutionPolicy -ExecutionPolicy Restricted -Scope LocalMachine
🧯 If You Can't Patch
- Implement strict monitoring of MVISION EDR administrative actions and PowerShell execution logs
- Segment network to limit lateral movement from potentially compromised endpoints
🔍 How to Verify
Check if Vulnerable:
Check MVISION EDR server version in the administration console. If version is below 3.4.0, the system is vulnerable.Check Version:
Check version in MVISION EDR web console under Administration > System InformationVerify Fix Applied:
Confirm MVISION EDR server version is 3.4.0 or higher in the administration console and verify client components have updated.📡 Detection & Monitoring
Log Indicators:
- Unusual PowerShell command execution via MVISION EDR 'execute reaction'
- Multiple 'execute reaction' commands from single administrator in short timeframe
- PowerShell commands containing suspicious patterns (downloads, encoded commands, etc.)
Network Indicators:
- Unexpected outbound connections from endpoints following MVISION EDR administrative actions
- Command and control traffic patterns from previously quiet systems
SIEM Query:
source="mvision_edr" AND action="execute_reaction" AND (command="*powershell*" OR command="*cmd*" OR command="*download*" OR command="*encodedcommand*")