CVE-2021-47879: eBeam Interactive Suite Privilege Escalation

CVE-2021-47879 Overview

CVE-2021-47879 is an unquoted service path vulnerability affecting eBeam Interactive Suite 3.6. The vulnerability exists in the eBeam Stylus Driver service, which contains an improperly quoted service path that allows local users to potentially execute arbitrary code with elevated privileges. Attackers can exploit the unquoted path in C:\Program Files (x86)\Luidia\eBeam Stylus Driver\ to inject malicious executables that would run with LocalSystem permissions, effectively gaining complete control over the affected system.

Critical Impact

Local privilege escalation to LocalSystem permissions through malicious executable injection in unquoted service path

Affected Products

• eBeam Interactive Suite 3.6
• eBeam Stylus Driver Service
• Luidia eBeam Software Suite

Discovery Timeline

• 2026-01-21 - CVE-2021-47879 published to NVD
• 2026-01-21 - Last updated in NVD database

Technical Details for CVE-2021-47879

Vulnerability Analysis

This vulnerability is classified as CWE-428 (Unquoted Search Path or Element). When a Windows service is configured with an executable path that contains spaces but is not enclosed in quotation marks, Windows will attempt to locate and execute the binary by progressively parsing the path at each space character. For the path C:\Program Files (x86)\Luidia\eBeam Stylus Driver\, Windows will sequentially attempt to execute:

1. C:\Program.exe
2. C:\Program Files.exe
3. C:\Program Files (x86)\Luidia\eBeam.exe
4. C:\Program Files (x86)\Luidia\eBeam Stylus.exe

If an attacker can place a malicious executable in any of these locations before the legitimate service binary is found, the malicious code will execute instead with the privileges of the service—in this case, LocalSystem.

Root Cause

The root cause of this vulnerability is improper configuration of the Windows service registry entry for the eBeam Stylus Driver. The service's ImagePath value in the Windows registry does not enclose the executable path in double quotes, despite the path containing multiple spaces. This configuration oversight is a common issue in Windows software installations and represents a failure to follow Microsoft's best practices for service path configuration.

Attack Vector

This vulnerability requires local access to the target system. An attacker with low-privileged user access can exploit this vulnerability by placing a malicious executable file named Program.exe, Files.exe, Luidia.exe, eBeam.exe, or Stylus.exe in the appropriate directory location along the unquoted path. When the eBeam Stylus Driver service starts or restarts (such as during system reboot), Windows will execute the attacker's malicious file with LocalSystem privileges before reaching the legitimate service binary. The attacker must have write permissions to at least one directory in the path hierarchy, which may be possible depending on the system's security configuration. A public exploit is documented in Exploit-DB #49648.

Detection Methods for CVE-2021-47879

Indicators of Compromise

• Presence of unexpected executable files named Program.exe, Files.exe, eBeam.exe, or Stylus.exe in the root directory or intermediate path locations
• Unusual process execution originating from the LocalSystem account that does not match expected service behavior
• Modified file timestamps in C:\Program Files (x86)\Luidia\ directory or parent directories
• New or modified executables in the C:\ root directory or C:\Program Files (x86)\ folder

Detection Strategies

• Query Windows registry for unquoted service paths using PowerShell or WMI to identify vulnerable services: Get-WmiObject win32_service | Where-Object {$_.PathName -match ' ' -and $_.PathName -notmatch '^"'}
• Monitor for new file creation events in C:\, C:\Program Files\, and C:\Program Files (x86)\ directories for unexpected executable files
• Implement application whitelisting to prevent unauthorized executables from running with elevated privileges
• Use endpoint detection tools to alert on process creation events from service accounts executing from non-standard locations

Monitoring Recommendations

• Enable Windows Security Event logging for process creation (Event ID 4688) with command line auditing
• Configure file integrity monitoring for critical system directories and service installation paths
• Monitor for service configuration changes via registry modification events (Event ID 4657)
• Deploy SentinelOne agents to detect and prevent privilege escalation attempts through behavioral analysis

How to Mitigate CVE-2021-47879

Immediate Actions Required

• Verify the eBeam Stylus Driver service path configuration in the Windows registry and add quotation marks around the ImagePath value if missing
• Audit all directories in the unquoted path for unexpected executable files and remove any suspicious binaries
• Restrict write permissions on C:\, C:\Program Files\, and C:\Program Files (x86)\ directories to administrative users only
• Consider disabling the eBeam Stylus Driver service if not actively required until a vendor patch is available

Patch Information

There is currently no vendor patch information available for this vulnerability. Administrators should monitor the VulnCheck Advisory on eBeam for updates regarding official fixes from the vendor. Manual remediation by properly quoting the service path in the registry is recommended as an interim solution.

Workarounds

• Manually edit the Windows registry to add quotation marks around the service's ImagePath value
• Remove write permissions for standard users from all directories in the service path hierarchy
• Implement application control policies to prevent execution of unauthorized executables from system directories
• Disable or uninstall the eBeam Interactive Suite if the functionality is not required in your environment

# Registry fix to quote the service path (run as Administrator in PowerShell)
$serviceName = "eBeam Stylus Driver"
$regPath = "HKLM:\SYSTEM\CurrentControlSet\Services\$serviceName"
$currentPath = (Get-ItemProperty -Path $regPath -Name ImagePath).ImagePath
if ($currentPath -notmatch '^"') {
    Set-ItemProperty -Path $regPath -Name ImagePath -Value "`"$currentPath`""
    Write-Host "Service path has been quoted successfully"
}