CVE-2021-47833: WifiHotSpot Privilege Escalation Flaw

CVE-2021-47833 Overview

CVE-2021-47833 is an unquoted service path vulnerability affecting WifiHotSpot 1.0.0.0. The vulnerability exists in the WifiHotSpotService.exe service, which uses an unquoted path containing spaces. This allows local attackers to plant malicious executables in strategic locations that will be executed with elevated LocalSystem privileges when the service starts during system startup or reboot.

Critical Impact

Local attackers can achieve privilege escalation to LocalSystem by exploiting the unquoted service path, potentially gaining complete control over the affected system.

Affected Products

• WifiHotSpot 1.0.0.0
• WifiHotSpotService.exe component

Discovery Timeline

• 2026-01-16 - CVE CVE-2021-47833 published to NVD
• 2026-01-16 - Last updated in NVD database

Technical Details for CVE-2021-47833

Vulnerability Analysis

This vulnerability falls under CWE-428 (Unquoted Search Path or Element), a well-known Windows security issue affecting services with paths containing spaces. When a Windows service is registered with a path that contains spaces but is not enclosed in quotation marks, Windows attempts to resolve the path by trying various combinations of the path segments.

For example, if a service path is C:\Program Files\WifiHotSpot\WifiHotSpotService.exe, Windows will attempt to execute in order: C:\Program.exe, then C:\Program Files\WifiHotSpot\WifiHotSpotService.exe. An attacker with write access to C:\ or other intermediate directories can place a malicious executable named Program.exe that will be executed with the service's privileges.

The vulnerability requires local access to the system and the ability to write files to directories in the service path. Once exploited, the attacker gains LocalSystem privileges, the highest privilege level on a Windows system.

Root Cause

The root cause is improper configuration of the Windows service registration. The WifiHotSpotService.exe service path was registered without enclosing quotation marks around the full executable path. This is a common development oversight that occurs when services are installed in directories with spaces in their names (such as Program Files).

Attack Vector

The attack requires local access to the target system. An attacker must:

1. Identify that the WifiHotSpot service uses an unquoted path
2. Gain write access to a directory that appears earlier in the path resolution sequence (e.g., C:\ or C:\Program Files\)
3. Place a malicious executable with a name that Windows will attempt to execute first (e.g., Program.exe)
4. Wait for or trigger a system restart or service restart
5. The malicious executable runs with LocalSystem privileges

The exploitation is straightforward and does not require any user interaction beyond the service restart or system reboot. An existing proof-of-concept exploit is publicly available via Exploit-DB #49845.

Detection Methods for CVE-2021-47833

Indicators of Compromise

• Unexpected executables named Program.exe or similar in the root drive directory or intermediate path locations
• Suspicious files appearing in C:\ or C:\Program Files\ with execution timestamps coinciding with system startup
• Process execution events showing Program.exe spawning from unexpected locations with SYSTEM privileges
• New or modified files in service path directories that were not part of legitimate software installations

Detection Strategies

• Monitor for file creation events in C:\ and other common unquoted path exploitation locations using endpoint detection and response (EDR) tools
• Use Windows Security Event Log monitoring for suspicious service execution patterns (Event ID 7045 for new service installations)
• Implement file integrity monitoring on directories commonly targeted by unquoted service path attacks
• Scan the Windows registry for services with unquoted paths that contain spaces using tools like PowerShell or dedicated vulnerability scanners

Monitoring Recommendations

• Enable command-line process auditing to capture the full path of executed processes
• Configure SentinelOne Singularity to alert on process creation events from unexpected paths running as SYSTEM
• Implement baseline monitoring of startup executables and alert on deviations
• Regularly audit Windows services for unquoted path configurations using automated scripts

How to Mitigate CVE-2021-47833

Immediate Actions Required

• Audit the WifiHotSpot service registration and add quotation marks around the service path in the Windows registry
• Review directory permissions along the service path to restrict write access to administrators only
• Scan for any suspicious executables in C:\ and intermediate directories in the service path
• Consider disabling or uninstalling WifiHotSpot 1.0.0.0 until a patched version is available

Patch Information

No vendor patch information is currently available in the CVE data. Organizations should contact Gearbox Computers for remediation guidance. Additional information may be available via the VulnCheck Advisory on WiFiHotspotServiceExe or the Gearbox Computers Hotspot Info page.

Workarounds

• Manually fix the unquoted service path by modifying the registry key HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\WifiHotSpotService to enclose the ImagePath value in quotation marks
• Restrict write permissions on the C:\ drive and C:\Program Files\ directory to prevent unauthorized executable placement
• Implement application whitelisting to prevent execution of unauthorized executables from sensitive directories
• Use SentinelOne's behavioral AI to detect and block privilege escalation attempts through service path manipulation

# Registry fix example - Enclose service path in quotes
# Run as Administrator in PowerShell
$serviceName = "WifiHotSpotService"
$regPath = "HKLM:\SYSTEM\CurrentControlSet\Services\$serviceName"
$currentPath = (Get-ItemProperty -Path $regPath).ImagePath
# Add quotes if not present
if ($currentPath -notmatch '^".*"$') {
    $quotedPath = '"' + $currentPath + '"'
    Set-ItemProperty -Path $regPath -Name ImagePath -Value $quotedPath
}