CVE-2023-24927
📋 TL;DR
This vulnerability allows remote attackers to execute arbitrary code on systems using Microsoft PostScript and PCL6 Class Printer Drivers. Attackers can 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 administrative privileges, enabling data theft, ransomware deployment, or persistent backdoor installation.
Likely Case
Privilege escalation leading to lateral movement within networks, particularly in enterprise environments with shared print servers.
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 some level of access to the print system, either locally or via network.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Security updates released in May 2023 (KB5026372 for Windows 10, KB5026370 for Windows 11, etc.)
Vendor Advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2023-24927
Restart Required: Yes
Instructions:
1. Apply May 2023 security updates from Windows Update. 2. For enterprise environments, deploy updates via WSUS or SCCM. 3. Restart affected systems after patch installation.
🔧 Temporary Workarounds
Disable vulnerable printer drivers
windowsRemove or disable Microsoft PostScript and PCL6 Class Printer Drivers from systems
Remove-PrinterDriver -Name "Microsoft PostScript Printer Driver"
Remove-PrinterDriver -Name "Microsoft PCL6 Class Printer Driver"
Restrict print spooler access
windowsConfigure firewall rules to restrict access to print spooler service (port 445, 139, 9100)
New-NetFirewallRule -DisplayName "Block Print Spooler" -Direction Inbound -Protocol TCP -LocalPort 445,139,9100 -Action Block
🧯 If You Can't Patch
- Network segmentation: Isolate print servers from critical systems and restrict access to authorized users only.
- Monitor print spooler logs for unusual activity and implement strict access controls on print management interfaces.
🔍 How to Verify
Check if Vulnerable:
Check if Microsoft PostScript or PCL6 Class Printer Drivers are installed via Print Management console or PowerShell: Get-PrinterDriver | Where-Object {$_.Name -like "*PostScript*" -or $_.Name -like "*PCL6*"}Check Version:
systeminfo | findstr /B /C:"OS Name" /C:"OS Version"Verify Fix Applied:
Verify May 2023 security updates are installed: Get-HotFix | Where-Object {$_.HotFixID -like "KB50263*"}📡 Detection & Monitoring
Log Indicators:
- Event ID 307 in Windows Print Service logs for failed print jobs
- Unusual print job submissions from unexpected sources
- Print spooler service crashes (Event ID 7031)
Network Indicators:
- Unusual SMB traffic to print servers
- Print job submissions over non-standard ports
- Multiple failed authentication attempts to print services
SIEM Query:
source="Windows" AND (event_id=307 OR event_id=7031) AND (process="spoolsv.exe" OR service="Spooler")