CVE-2021-47883: Sandboxie Plus Privilege Escalation Flaw

CVE-2021-47883 Overview

CVE-2021-47883 is an unquoted service path vulnerability affecting Sandboxie Plus version 0.7.2. The vulnerability exists in the SbieSvc service, which allows local attackers to execute arbitrary code with elevated privileges. By exploiting the unquoted binary path in the service configuration, attackers can place malicious executables in specific filesystem locations that will be executed with LocalSystem permissions when the service starts.

Critical Impact

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

Affected Products

• Sandboxie Plus 0.7.2
• SbieSvc service component
• Windows systems running vulnerable Sandboxie Plus installations

Discovery Timeline

• 2026-01-21 - CVE CVE-2021-47883 published to NVD
• 2026-01-21 - Last updated in NVD database

Technical Details for CVE-2021-47883

Vulnerability Analysis

This vulnerability is classified as CWE-428 (Unquoted Search Path or Element). When Windows services are configured with executable paths containing spaces that are not enclosed in quotation marks, the operating system interprets the path ambiguously during service startup. This creates an opportunity for attackers to place malicious executables in locations that Windows will attempt to execute before reaching the intended service binary.

The SbieSvc service in Sandboxie Plus 0.7.2 stores its executable path without proper quoting in the Windows Service Control Manager registry. When the path contains spaces (such as C:\Program Files\Sandboxie-Plus\SbieSvc.exe), Windows attempts to locate and execute binaries at intermediate path locations. An attacker with write access to directories like C:\Program.exe or C:\Program Files\Sandboxie-Plus\ can place a malicious executable that will be launched with LocalSystem privileges when the service starts.

Root Cause

The root cause is improper service registration where the binary path for the SbieSvc service is stored without surrounding quotation marks in the Windows registry. The service path should be enclosed in quotes to prevent Windows from misinterpreting paths with embedded spaces.

Attack Vector

The attack requires local access to the system. An attacker must have sufficient filesystem permissions to write an executable to a location within the unquoted path that Windows will evaluate before the legitimate service binary. When the SbieSvc service is started (either manually, at system boot, or through a restart trigger), the attacker's malicious binary executes with LocalSystem privileges, achieving vertical privilege escalation.

The exploitation process involves identifying the unquoted service path using tools like wmic service get name,pathname or querying the registry directly, then placing a malicious executable (such as Program.exe in C:\) that Windows will execute during path resolution. Additional technical details are available in the Exploit-DB #49631 and VulnCheck Advisory.

Detection Methods for CVE-2021-47883

Indicators of Compromise

• Unexpected executables named Program.exe, Sandboxie-Plus.exe, or similar variants in C:\ or C:\Program Files\ directories
• Suspicious process creation events with parent process SbieSvc or services.exe
• Unauthorized modifications to directories within the Sandboxie Plus installation path

Detection Strategies

• Query Windows services for unquoted paths using wmic service get name,pathname,startmode | findstr /i "auto" | findstr /i /v """ to identify vulnerable configurations
• Monitor file system activity for creation of executables in common exploitation paths like C:\Program.exe or C:\Program Files\Sandboxie-Plus\
• Implement endpoint detection rules to alert on process chains where services.exe spawns unexpected child processes

Monitoring Recommendations

• Enable Windows Security Event logging for service installation events (Event ID 7045) and process creation (Event ID 4688)
• Deploy SentinelOne behavioral AI to detect privilege escalation attempts via service manipulation
• Monitor registry keys under HKLM\SYSTEM\CurrentControlSet\Services\SbieSvc for ImagePath modifications

How to Mitigate CVE-2021-47883

Immediate Actions Required

• Upgrade Sandboxie Plus to a version newer than 0.7.2 that addresses this vulnerability
• Manually correct the service path by adding quotation marks around the binary path in the registry
• Review filesystem permissions on directories within the unquoted path to restrict write access to administrators only
• Audit existing systems for signs of exploitation before applying fixes

Patch Information

Users should upgrade to a patched version of Sandboxie Plus. Check the Sandboxie Plus Official Site for the latest security updates and release notes. After upgrading, verify the service path is properly quoted by inspecting the ImagePath value in the Windows registry under HKLM\SYSTEM\CurrentControlSet\Services\SbieSvc.

Workarounds

• Manually quote the service path by modifying the registry value at HKLM\SYSTEM\CurrentControlSet\Services\SbieSvc\ImagePath to include quotation marks around the executable path
• Restrict write permissions on C:\ and C:\Program Files\ directories to prevent placement of malicious executables
• Disable the SbieSvc service if not actively required until a patch can be applied

# Manual registry fix to quote the service path (run as Administrator)
# First, backup the current value, then update with quoted path
reg query "HKLM\SYSTEM\CurrentControlSet\Services\SbieSvc" /v ImagePath
reg add "HKLM\SYSTEM\CurrentControlSet\Services\SbieSvc" /v ImagePath /t REG_EXPAND_SZ /d "\"C:\Program Files\Sandboxie-Plus\SbieSvc.exe\"" /f