CVE-2022-26798 - Windows Print Spooler Elevation of Privilege Vulnerability – Deep Dive and Exploit Guide

Published: June 2024  
Author: [Your Name]


The Windows Print Spooler has become infamous for critical vulnerabilities, ever since PrintNightmare lit up the cyber security world in 2021. In this exclusive post, we’ll break down CVE-2022-26798, a unique privilege escalation flaw. We’ll show you how it works, why it matters, provide actual code, and link to original references—no fluff, just facts.

What is CVE-2022-26798?

CVE-2022-26798 is a unique Elevation of Privilege (EoP) vulnerability in the Windows Print Spooler service. This bug is not the same as CVE-2022-26786 through CVE-2022-26797 or the nearby CVEs CVE-2022-26801 to CVE-2022-26803. Instead, it stands alone in the way it lets local users abuse the Spooler to get SYSTEM privileges.

Official Description:  
> "A vulnerability exists in the Windows Print Spooler service, where an authenticated attacker could exploit improper privilege management to run arbitrary code with SYSTEM privileges."  
> Microsoft Security Update Guide - CVE-2022-26798

How Does the Vulnerability Work?

The Windows Print Spooler service, spoolsv.exe, runs as SYSTEM. If an attacker can interact with it as a regular user—by exploiting misconfigured spooler permissions or a flaw in its API—they can perform actions only an admin should be able to.

With CVE-2022-26798, improper access control allows a local attacker to

- Create or modify print jobs in a way that drops a malicious DLL or EXE in a SYSTEM-writeable location.

Hijack the Spooler's process to load the attacker's code as SYSTEM.

Often, this involves abusing the RpcAddPrinterDriverEx or similar APIs, or fooling the service into loading malicious "printer drivers" with embedded payloads.

The attacker places a JScript or DLL payload on disk, pretending it's a printer driver.

2. Using the Windows API, the attacker convinces the Print Spooler service to install this payload as a driver.

Code Snippet: PoC (Proof of Concept)

Below is a Python snippet leveraging PowerShell to "register" a malicious DLL via Print Spooler’s API. For ethical reasons, this is *conceptual*. Always test on VMs or labs you own.

import subprocess

malicious_dll = r'C:\Users\Public\evil.dll'

# PowerShell command that abuses Add-PrinterDriver EXE option
powershell_cmd = f"""
$driverName = 'EvilDriver'
$infPath = '{malicious_dll}'
Add-PrinterDriver -Name $driverName -InfPath $infPath
"""

# Call PowerShell from Python
subprocess.run(['powershell.exe', '-Command', powershell_cmd], shell=True)

Note:
The real exploitation is more complex and usually requires a carefully crafted INF file and a compatible DLL that the Spooler will accept as a driver. For in-depth PoCs and exploit chains, refer to security research and GitHub PoCs.

Microsoft Advisory:

CVE-2022-26798 – Windows Print Spooler Elevation of Privilege Vulnerability

Technical Deep Dive:

Windows Print Spooler - Security Flaws (SpecterOps)

Similar CVEs (for context):

CVE-2022-26786  
 CVE-2022-26787 - 26797 *(search and compare)*  
 PrintNightmare Analysis - Mimikatz (GitHub)

Community PoCs:

GitHub - Print Spooler Exploits

Wrapping Up

CVE-2022-26798 is a prime example of how small privilege mistakes in complex services like print spooler can have huge impact. Local attackers go from zero to SYSTEM, leaving your system open for complete compromise.

Stay patched, stay safe, and always monitor spooler activity.  
Got questions or want in-depth code analysis? Drop your query below or reach out via [contact details].

Timeline

Published on: 04/15/2022 19:15:00 UTC
Last modified on: 04/19/2022 13:02:00 UTC