CVE-2020-36976: Acer Registration Service Path Vulnerability

CVE-2020-36976 Overview

CVE-2020-36976 is an unquoted service path vulnerability affecting Acer Global Registration Service version 1.0.0.3. This security flaw exists in the service configuration where the executable path contains spaces but lacks proper quotation marks. This misconfiguration allows local attackers to potentially execute arbitrary code by placing a malicious executable in a strategic location along the unquoted path, which Windows would execute with elevated LocalSystem privileges during service startup.

Critical Impact

Local attackers can exploit this unquoted service path to achieve privilege escalation and execute arbitrary code with LocalSystem privileges on affected Acer systems.

Affected Products

• Acer Global Registration Service version 1.0.0.3
• Acer systems with GregSvc.exe service installed
• Windows systems with the vulnerable service configuration at C:\Program Files (x86)\Acer\Registration\

Discovery Timeline

• 2026-01-27 - CVE CVE-2020-36976 published to NVD
• 2026-01-29 - Last updated in NVD database

Technical Details for CVE-2020-36976

Vulnerability Analysis

This vulnerability falls under CWE-428 (Unquoted Search Path or Element), a configuration weakness that occurs when a Windows service path containing spaces is not properly enclosed in quotation marks. The Acer Global Registration Service (GregSvc.exe) is configured with an unquoted path at C:\Program Files (x86)\Acer\Registration\. When Windows attempts to start this service, it parses the path sequentially, checking for executables at each space-delimited segment before reaching the intended target.

The vulnerability requires local access to the system and the ability to write files to directories along the service path. Once exploited, an attacker gains code execution in the context of LocalSystem, which is the highest privilege level on a Windows system. This represents a significant privilege escalation vector for attackers who have already gained initial access to a target system with limited user privileges.

Root Cause

The root cause of this vulnerability lies in improper service registration within the Windows Service Control Manager (SCM). When the Acer Global Registration Service was installed, its ImagePath registry value was configured without quotation marks around the full path to the executable. Windows path parsing interprets spaces as argument delimiters when the path is unquoted, causing the operating system to search for executables at truncated path locations before the intended target.

Attack Vector

The attack requires local access to the vulnerable system. An attacker would need to place a malicious executable named Program.exe in the root of the C:\ drive, or create intermediate directories such as C:\Program Files (x86)\Acer\Registration.exe. When the service starts (either during system boot or manual restart), Windows will attempt to execute these strategically placed files with LocalSystem privileges before finding the legitimate service executable.

The attack path exploitation follows this sequence: Windows parses the unquoted path C:\Program Files (x86)\Acer\Registration\GregSvc.exe and attempts to execute, in order: C:\Program.exe, then C:\Program Files.exe, then C:\Program Files (x86)\Acer\Registration.exe. If an attacker places a malicious binary at any of these locations and has appropriate filesystem permissions, code execution occurs with elevated privileges.

For technical details and proof-of-concept information, refer to the Exploit-DB #49142 entry and the VulnCheck Advisory.

Detection Methods for CVE-2020-36976

Indicators of Compromise

• Presence of unexpected executables such as Program.exe, Program Files.exe, or Registration.exe in the C:\ drive root or along the Acer installation path
• Unusual child processes spawned by the GregSvc.exe service or Windows Service Control Manager
• File creation events in C:\Program Files (x86)\Acer\ with non-standard executable names
• Registry modifications to the ImagePath value under HKLM\SYSTEM\CurrentControlSet\Services\GregSvc

Detection Strategies

• Monitor for file creation events in C:\, C:\Program Files\, and C:\Program Files (x86)\ directories for executables with names matching common unquoted path exploitation patterns
• Query Windows services for unquoted ImagePath values using PowerShell: Get-WmiObject Win32_Service | Where-Object {$_.PathName -notlike '"*"' -and $_.PathName -like '* *'}
• Implement endpoint detection rules to alert on suspicious process hierarchies originating from service executables
• Deploy SentinelOne's behavioral AI to detect privilege escalation attempts through service manipulation

Monitoring Recommendations

• Enable Windows Security Event logging for service start events (Event ID 7036) and correlate with process creation events
• Configure file integrity monitoring on system directories prone to unquoted path exploitation
• Implement SentinelOne Singularity XDR to detect anomalous process execution patterns and privilege escalation techniques

How to Mitigate CVE-2020-36976

Immediate Actions Required

• Audit all Acer systems for the presence of the vulnerable Global Registration Service version 1.0.0.3
• Verify filesystem permissions on C:\ and C:\Program Files (x86)\Acer\ to ensure non-administrative users cannot create files
• Consider disabling or removing the Acer Global Registration Service if not required for business operations
• Deploy endpoint protection solutions capable of detecting unquoted service path exploitation attempts

Patch Information

No official patch information is currently available from Acer for this vulnerability. Administrators should consult the Acer support website for potential updates. In the absence of an official patch, manual remediation through registry modification is recommended as described below.

Workarounds

• Manually fix the unquoted service path by adding quotation marks to the ImagePath registry value under HKLM\SYSTEM\CurrentControlSet\Services\GregSvc
• Restrict write permissions on directories along the service path to prevent unauthorized file placement
• Disable the Acer Global Registration Service if it is not essential for system functionality
• Deploy application whitelisting to prevent unauthorized executables from running in system directories

# PowerShell remediation to quote the service path
$servicePath = 'HKLM:\SYSTEM\CurrentControlSet\Services\GregSvc'
$currentPath = (Get-ItemProperty -Path $servicePath).ImagePath
if ($currentPath -notlike '"*') {
    $quotedPath = '"{0}"' -f $currentPath
    Set-ItemProperty -Path $servicePath -Name ImagePath -Value $quotedPath
    Write-Host "Service path has been quoted: $quotedPath"
}