CVE-2021-42987
📋 TL;DR
CVE-2021-42987 is an integer overflow vulnerability in Eltima USB Network Gate's IOCTL handler that allows local attackers to execute arbitrary code with kernel privileges or cause denial of service through memory corruption. This affects users of USB Network Gate versions 7.0.1370 through 9.2.2420. Attackers can exploit this to gain complete system control or crash the operating system.
💻 Affected Systems
- Eltima USB Network Gate
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise via kernel-mode arbitrary code execution leading to full administrative control, data theft, and persistent backdoor installation.
Likely Case
Local privilege escalation from standard user to SYSTEM/root privileges, enabling lateral movement and persistence establishment.
If Mitigated
Limited impact if proper access controls prevent local user access or if vulnerable software is not installed.
🎯 Exploit Status
Exploitation requires local access but the vulnerability is in a commonly used driver with public technical details available.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Version 9.2.2420 and later
Vendor Advisory: https://www.eltima.com/security-advisory/
Restart Required: Yes
Instructions:
1. Download latest version from Eltima website. 2. Uninstall current version. 3. Install updated version. 4. Restart system.
🔧 Temporary Workarounds
Restrict driver access
allLimit access to the vulnerable driver using Windows security policies or Linux permissions
Windows: icacls "C:\Program Files\Eltima Software\USB Network Gate\*" /deny Users:(RX)
Linux: chmod 750 /usr/local/bin/usbgate
Disable vulnerable service
allStop and disable the USB Network Gate service if not required
Windows: sc stop "USB Network Gate" && sc config "USB Network Gate" start= disabled
Linux: systemctl stop usbgate && systemctl disable usbgate
🧯 If You Can't Patch
- Remove USB Network Gate software completely if not essential
- Implement strict local access controls and monitor for suspicious driver activity
🔍 How to Verify
Check if Vulnerable:
Check installed version of USB Network Gate against vulnerable range 7.0.1370-9.2.2420Check Version:
Windows: "C:\Program Files\Eltima Software\USB Network Gate\usbgate.exe" --version | Linux: usbgate --version | macOS: /Applications/USB\ Network\ Gate.app/Contents/MacOS/usbgate --versionVerify Fix Applied:
Confirm version is 9.2.2420 or higher and verify driver files have been updated📡 Detection & Monitoring
Log Indicators:
- Unusual IOCTL requests to USB Network Gate driver
- Privilege escalation attempts from standard users
- Crash dumps related to usbgate.sys or similar driver files
Network Indicators:
- Local system calls to vulnerable driver interface
SIEM Query:
EventID=4688 AND (ProcessName LIKE '%usbgate%' OR CommandLine LIKE '%IOCTL%22001B%')