CVE-2021-42990
📋 TL;DR
This vulnerability in FlexiHub for Windows allows local attackers to execute arbitrary code with kernel privileges or crash the operating system through a buffer overflow in an IOCTL handler. It affects users running vulnerable versions of FlexiHub on Windows systems. Attackers need local access to exploit this flaw.
💻 Affected Systems
- FlexiHub for Windows
📦 What is this software?
Flexihub by Flexihub
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with kernel-level code execution leading to persistent backdoors, data theft, or ransomware deployment.
Likely Case
Local privilege escalation allowing attackers to gain SYSTEM privileges from a lower-privileged account.
If Mitigated
Denial of service through OS crash if exploit attempts fail or are detected.
🎯 Exploit Status
Exploitation requires crafting specific IOCTL requests. Local access needed but no authentication required beyond having user access.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 5.3.14268 or later
Vendor Advisory: https://www.flexihub.com/
Restart Required: Yes
Instructions:
1. Download latest version from FlexiHub website. 2. Uninstall current version. 3. Install updated version. 4. Restart system.
🔧 Temporary Workarounds
Disable FlexiHub Service
windowsStop and disable the FlexiHub service to prevent exploitation
sc stop FlexiHub
sc config FlexiHub start= disabled
Remove Vulnerable Driver
windowsUninstall FlexiHub completely if not needed
appwiz.cpl
Select FlexiHub and click Uninstall
🧯 If You Can't Patch
- Restrict local access to systems with FlexiHub installed
- Implement application whitelisting to prevent unauthorized process execution
🔍 How to Verify
Check if Vulnerable:
Check FlexiHub version in Control Panel > Programs and Features. If version is between 2.0.4340 and 5.3.14268, system is vulnerable.Check Version:
wmic product where name="FlexiHub" get versionVerify Fix Applied:
Verify FlexiHub version is 5.3.14268 or higher after update.📡 Detection & Monitoring
Log Indicators:
- Unusual IOCTL requests to FlexiHub driver
- System crashes or BSOD events
- Unexpected privilege escalation events
Network Indicators:
- Not applicable - local exploit only
SIEM Query:
EventID=4688 AND (ProcessName LIKE '%FlexiHub%' OR CommandLine CONTAINS 'FlexiHub') AND NewTokenElevationType=2