CVE-2024-26158 - Exploiting Microsoft Install Service Elevation of Privilege Vulnerability

In March 2024, Microsoft patched a serious vulnerability tracked as CVE-2024-26158 in the Microsoft Install Service. This flaw allows a local attacker to escalate their privileges—meaning someone with just basic access on a Windows machine could become an administrator. If you’re a Windows system administrator, security enthusiast, or simply want to understand how modern privilege escalation attacks work, this post is for you.

This post will break down the vulnerability in simple terms, show you how attackers might exploit it, provide example code, and link to original sources for further reading.

What is CVE-2024-26158?

CVE-2024-26158 (Microsoft Install Service Elevation of Privilege Vulnerability) affects the Microsoft Install Service, a core Windows component used to help install, update, and maintain software. Microsoft assigned this a CVSS score of 7.8, marking it as high severity.

When exploited, this vulnerability allows a local attacker (someone already logged into the system, but with limited rights) to run code with SYSTEM privileges. SYSTEM is the most powerful user account on Windows—giving full control over files, users, and much more.

References

- Microsoft Security Guide on CVE-2024-26158
- CVE Details Page

Vulnerability Details

At its core, the issue happens because the Install Service does not securely check permissions when interacting with specific files or registry entries. Attackers can exploit this by tricking the service into running malicious files or commands with SYSTEM rights.

Microsoft says

> *“An attacker who successfully exploited this vulnerability could gain SYSTEM privileges. The attacker would need to have local access to the targeted computer.”*

2. Craft a malicious file or binary placed in a location where the Install Service expects to find a legitimate file it will run.

Gain a SYSTEM shell, giving full control.

Note: The actual “install” operation may require creating or replacing an installer/uninstaller file, DLL, or registry key, depending on the vulnerability subtype.

Example Exploit (Proof of Concept)

While the exact exploit might vary, here’s a simplified pseudo-proof-of-concept in PowerShell, showing how an attacker might drop a backdoor and leverage the Install Service to run it as SYSTEM.

> DISCLAIMER: FOR EDUCATIONAL PURPOSES ONLY!

# 1. Copy malicious binary to vulnerable folder (replace with actual vulnerable path)
$MaliciousBin = "C:\Users\User\malicious.exe"
$TargetPath = "C:\ProgramData\WindowsInstaller\"

Copy-Item $MaliciousBin $TargetPath

# 2. (Ab)use the Install Service to trigger execution
# For example, launch an install/uninstall process that picks up the malicious.exe
Start-Process msiexec.exe -ArgumentList "/i C:\ProgramData\WindowsInstaller\malicious.exe" -Wait

# 3. You now have SYSTEM level execution if the exploit succeeds!

In reality, you’d need to

- Identify the exact folder or file/action the Install Service references insecurely.

Why This Is Dangerous

Privilege escalation bugs like this are a favorite tool for attackers. Why? Because malware usually lands on a system as a low-level user, but with bugs like CVE-2024-26158, it can quickly become SYSTEM and take over everything. This is commonly seen in ransomware attacks, data theft, and persistence mechanisms.

Mitigation & Recommendations

- Patch now! Microsoft has already released updates. Always update Windows and related services as soon as possible.
- Direct Microsoft Patch Information

Here is a quick summary of vital facts

| Field | Value |
|------------------|--------------------------------------------------------|
| Vulnerability | CVE-2024-26158 |
| Component | Microsoft Install Service |
| Impact | Local Privilege Escalation (to SYSTEM) |
| Attack Vector | Local |
| Exploit Code | Proofs-of-concept are possible and may be public soon |
| Patch Released | March 2024 |
| Severity | High (CVSS 7.8) |
| References | MSRC Advisory |

Conclusion

CVE-2024-26158 is a perfect example of how simple missteps in Windows services can become powerful tools for attackers. If you’re managing Windows systems, staying up-to-date with official patches is essential to avoid severe privilege escalation attacks. Always monitor for suspicious activity, especially around core services like msiexec or anything involving software installation.

Timeline

Published on: 04/09/2024 17:15:35 UTC
Last modified on: 04/10/2024 13:24:00 UTC