CVE-2023-23403
📋 TL;DR
This vulnerability allows remote attackers to execute arbitrary code on systems using Microsoft PostScript and PCL6 Class Printer Drivers. An attacker could exploit this by sending specially crafted print jobs to vulnerable systems. Affected systems include Windows servers and workstations with these printer drivers installed.
💻 Affected Systems
- Microsoft PostScript Printer Driver
- Microsoft PCL6 Class Printer Driver
📦 What is this software?
Windows 10 1507 by Microsoft
Windows 10 1607 by Microsoft
Windows 10 1809 by Microsoft
Windows 10 20h2 by Microsoft
Windows 10 21h2 by Microsoft
Windows 10 22h2 by Microsoft
Windows 11 21h2 by Microsoft
Windows 11 22h2 by Microsoft
⚠️ Risk & Real-World Impact
Worst Case
Full system compromise with attacker gaining SYSTEM privileges, enabling data theft, ransomware deployment, or persistent backdoor installation.
Likely Case
Privilege escalation leading to lateral movement within networks, credential harvesting, and installation of additional malware.
If Mitigated
Limited impact with proper network segmentation and print server isolation, potentially only affecting the print spooler service.
🎯 Exploit Status
Exploitation requires sending malicious print jobs to vulnerable systems. Attackers need network access to print services.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Security updates released March 14, 2023 (KB5023696, KB5023697, etc.)
Vendor Advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2023-23403
Restart Required: Yes
Instructions:
1. Apply March 2023 Windows security updates via Windows Update. 2. For enterprise environments, deploy updates through WSUS or SCCM. 3. Restart affected systems after patch installation.
🔧 Temporary Workarounds
Disable Print Spooler Service
windowsDisables the Print Spooler service to prevent print job processing
sc config spooler start= disabled
sc stop spooler
Restrict Print Server Access
windowsConfigure firewall rules to limit access to print services
netsh advfirewall firewall add rule name="Block Print Ports" dir=in action=block protocol=TCP localport=515,631,9100
🧯 If You Can't Patch
- Isolate print servers in dedicated network segments with strict access controls
- Implement application whitelisting to prevent unauthorized code execution
🔍 How to Verify
Check if Vulnerable:
Check if March 2023 security updates are installed via 'wmic qfe list' or 'Get-Hotfix -Id KB5023696'Check Version:
wmic printerdriver get name, driverversion | findstr /i "PostScript PCL6"Verify Fix Applied:
Verify security update KB5023696 or later is installed and Print Spooler service is running version 10.0.xxxxx.xxxx or higher📡 Detection & Monitoring
Log Indicators:
- Event ID 307 in Windows Print Service logs showing failed print jobs
- Unexpected Print Spooler service crashes (Event ID 7031)
Network Indicators:
- Unusual print job submissions to print servers
- Traffic to print ports (515, 631, 9100) from unexpected sources
SIEM Query:
source="Windows Security" event_id=4688 process_name="spoolsv.exe" AND command_line CONTAINS suspicious