CVE-2021-47762: HTTPDebuggerPro Privilege Escalation

CVE-2021-47762 Overview

HTTPDebuggerPro 9.11 contains an unquoted service path vulnerability (CWE-428) that allows local attackers to potentially execute arbitrary code with elevated system privileges. This vulnerability exists because the service executable path is not properly enclosed in quotation marks, enabling attackers to place malicious executables in strategic locations within the path hierarchy to hijack service execution.

Critical Impact

Local privilege escalation allowing attackers to execute arbitrary code with SYSTEM-level privileges through service path manipulation.

Affected Products

• HTTPDebuggerPro version 9.11
• HTTP Debugger Pro Windows Service component
• Systems running HTTPDebuggerPro with default installation paths

Discovery Timeline

• 2026-01-15 - CVE CVE-2021-47762 published to NVD
• 2026-01-16 - Last updated in NVD database

Technical Details for CVE-2021-47762

Vulnerability Analysis

The vulnerability stems from an unquoted service path configuration in HTTPDebuggerPro 9.11. When Windows services are installed with executable paths containing spaces but lacking proper quotation marks, the operating system's path resolution mechanism can be exploited. Windows parses unquoted paths by attempting to locate executables at each space boundary, creating opportunities for arbitrary code execution.

For example, if a service path is configured as C:\Program Files\HTTP Debugger\HTTPDebuggerSvc.exe, Windows will sequentially attempt to execute:

1. C:\Program.exe
2. C:\Program Files\HTTP.exe
3. C:\Program Files\HTTP Debugger\HTTPDebuggerSvc.exe

An attacker with write access to C:\ or C:\Program Files\ can place a malicious executable named Program.exe or HTTP.exe to intercept service execution and gain SYSTEM-level privileges.

Root Cause

The root cause is improper service registration during HTTPDebuggerPro installation. The service path was stored in the Windows Registry without enclosing quotation marks, failing to account for space characters in the directory path. This is a common oversight during application deployment that creates a local privilege escalation vector.

Attack Vector

This is a local attack vector requiring the attacker to have authenticated access to the target system with write permissions to directories within the service path hierarchy. The attacker must be able to place a malicious executable file in a location that precedes the legitimate service executable in the path resolution order. When the service starts or restarts, the malicious code executes with the service's elevated privileges, typically SYSTEM.

The attack requires:

1. Local access to the vulnerable system
2. Write permissions to a directory in the unquoted path
3. Knowledge of the vulnerable service path
4. Triggering a service restart (or waiting for system reboot)

Detection Methods for CVE-2021-47762

Indicators of Compromise

• Unexpected executable files such as Program.exe or HTTP.exe in root directories or C:\Program Files\
• Unusual service execution behavior or unexpected child processes spawned by HTTPDebuggerPro service
• Registry modifications to the HTTPDebuggerPro service ImagePath value
• Suspicious file creation events in system directories by non-administrative users

Detection Strategies

• Query Windows services for unquoted paths containing spaces using PowerShell: Get-WmiObject win32_service | Where-Object {$_.PathName -notlike '"*"' -and $_.PathName -like '* *'}
• Monitor file system changes in directories commonly exploited for unquoted path attacks
• Implement application whitelisting to prevent execution of unauthorized binaries in system paths
• Use endpoint detection tools to identify service execution anomalies

Monitoring Recommendations

• Enable Windows Security Event logging for service installation and modification events (Event IDs 7045, 7040)
• Configure file integrity monitoring on critical system directories
• Alert on new executable file creation in root and Program Files directories
• Monitor service startup patterns for unexpected execution paths

How to Mitigate CVE-2021-47762

Immediate Actions Required

• Audit the HTTPDebuggerPro service registry entry at HKLM\SYSTEM\CurrentControlSet\Services\ for unquoted paths
• Manually update the service ImagePath registry value to include proper quotation marks around the executable path
• Remove any suspicious executables from directories within the service path hierarchy
• Consider upgrading to a patched version of HTTPDebuggerPro if available from the vendor

Patch Information

Users should check the HTTP Debugger official website for updated versions that address this vulnerability. Additionally, technical details and proof-of-concept information are available via Exploit-DB #50545.

Workarounds

• Manually fix the registry entry by adding quotation marks around the service path: change the ImagePath value to properly quote the full path
• Restrict write permissions on directories within the service path to administrators only
• Implement application control policies to prevent unauthorized executable execution
• Use Windows built-in tools like sc qc HTTPDebuggerSvc to verify service path configuration

# Configuration example - Fix unquoted service path via registry
# Check current service path configuration
sc qc HTTPDebuggerSvc

# Update registry to add quotation marks (run as Administrator)
reg add "HKLM\SYSTEM\CurrentControlSet\Services\HTTPDebuggerSvc" /v ImagePath /t REG_EXPAND_SZ /d "\"C:\Program Files\HTTP Debugger\HTTPDebuggerSvc.exe\"" /f

# Verify the change
sc qc HTTPDebuggerSvc