CVE-2016-20057: NETGATE Registry Cleaner Escalation Flaw

CVE-2016-20057 Overview

CVE-2016-20057 is an unquoted service path vulnerability in NETGATE Registry Cleaner build 16.0.205. The NGRegClnSrv service contains an improperly quoted service binary path that allows local attackers to escalate privileges. By placing a malicious executable in the unquoted path and triggering a service restart or system reboot, attackers can execute arbitrary code with LocalSystem privileges.

Critical Impact

Local privilege escalation to LocalSystem, allowing complete system compromise through malicious executable placement in unquoted service paths.

Affected Products

• NETGATE Registry Cleaner build 16.0.205
• NGRegClnSrv Service Component

Discovery Timeline

• 2026-04-04 - CVE-2016-20057 published to NVD
• 2026-04-07 - Last updated in NVD database

Technical Details for CVE-2016-20057

Vulnerability Analysis

This vulnerability falls under CWE-428 (Unquoted Search Path or Element), a common misconfiguration in Windows services. When a Windows service binary path contains spaces and is not enclosed in quotation marks, the Windows Service Control Manager (SCM) attempts to interpret the path using a specific search order. The SCM tokenizes the path at each space and tries to execute each partial path as a potential executable.

For example, if the service path is C:\Program Files\NETGATE\Registry Cleaner\NGRegClnSrv.exe, Windows will attempt to execute in the following order:

1. C:\Program.exe
2. C:\Program Files\NETGATE\Registry.exe
3. C:\Program Files\NETGATE\Registry Cleaner\NGRegClnSrv.exe

An attacker with local write access to any of these directories can place a malicious executable (e.g., Registry.exe) that will be executed with LocalSystem privileges when the service starts.

Root Cause

The root cause is improper quoting of the service binary path in the Windows Registry during the NETGATE Registry Cleaner installation process. The installer fails to wrap the executable path in double quotes, leaving the service vulnerable to path injection attacks. This is a common developer oversight when registering Windows services with paths containing spaces.

Attack Vector

The attack requires local access to the target system with the ability to write files to directories in the unquoted path. The attacker must:

1. Identify the unquoted service path using tools like wmic service get name,pathname or registry inspection
2. Determine a writable directory along the tokenized path segments
3. Place a malicious executable with the appropriate name (e.g., Registry.exe) in the writable location
4. Wait for or trigger a service restart or system reboot

Upon service start, Windows SCM will execute the attacker's malicious binary with LocalSystem privileges instead of the intended NGRegClnSrv service executable.

Detection Methods for CVE-2016-20057

Indicators of Compromise

• Unexpected executables named Program.exe, Registry.exe, or similar in C:\, C:\Program Files\, or C:\Program Files\NETGATE\ directories
• Suspicious process execution originating from unexpected locations with SYSTEM privileges
• Modified timestamps on executable files in common Windows directories
• New services or scheduled tasks created after exploitation

Detection Strategies

• Monitor for new executable file creation in root directories and Program Files subdirectories using file integrity monitoring (FIM) tools
• Use SIEM rules to detect process execution from unusual paths with elevated privileges
• Implement Windows Event Log monitoring for Service Control Manager events (Event IDs 7000, 7045) showing unexpected service binaries
• Deploy endpoint detection rules that flag executable creation in directories matching common unquoted path patterns

Monitoring Recommendations

• Enable PowerShell script block logging and module logging to detect reconnaissance commands like wmic service get pathname
• Configure Windows Defender Application Control (WDAC) or AppLocker policies to restrict executable execution from non-standard paths
• Implement continuous vulnerability scanning to detect unquoted service paths across the environment
• Use SentinelOne's behavioral AI to detect privilege escalation attempts and unauthorized code execution with SYSTEM privileges

How to Mitigate CVE-2016-20057

Immediate Actions Required

• Audit all installed services for unquoted paths using the command: wmic service get name,pathname | findstr /i "Program Files"
• Review and restrict write permissions on directories in the service path (e.g., C:\Program Files\NETGATE\)
• Consider uninstalling NETGATE Registry Cleaner if not actively required
• Monitor for suspicious executable files in affected directories

Patch Information

No vendor patch information is currently available for this vulnerability. Users should consult the NETGATE official website for any security updates or newer builds that address this issue. Additional technical details are available in the Exploit-DB #40539 advisory and the VulnCheck Advisory.

Workarounds

• Manually fix the unquoted service path by modifying the Windows Registry key at HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\NGRegClnSrv to include proper quotation marks around the ImagePath value
• Restrict file system permissions on directories in the service path to prevent unauthorized executable placement
• Implement application whitelisting to prevent execution of unauthorized binaries with elevated privileges
• Disable the NGRegClnSrv service if not required using sc config NGRegClnSrv start= disabled

# Registry fix example - Wrap service path in quotes
# Run as Administrator in PowerShell
$regPath = "HKLM:\SYSTEM\CurrentControlSet\Services\NGRegClnSrv"
$currentPath = (Get-ItemProperty -Path $regPath).ImagePath
if ($currentPath -notmatch '^".*"$') {
    Set-ItemProperty -Path $regPath -Name ImagePath -Value "`"$currentPath`""
    Write-Host "Service path has been quoted to prevent exploitation"
}