CVE-2024-26238: Microsoft PLUGScheduler Scheduled Task Elevation of Privilege Vulnerability

In this post, we will explore the recently discovered vulnerability in Microsoft's PLUGScheduler, tracked under the identifier CVE-2024-26238. This vulnerability, classified as an Elevation of Privilege (EoP) flaw, enables attackers to gain unauthorized access to higher privilege levels on the target system. By exploiting this vulnerability, a threat actor could potentially execute malicious code, access sensitive information, or perform other privileged actions.

To help those affected by this security issue, we'll discuss the flaw's details, prerequisites for exploitation, evidence of exploitation, code snippets, and links to original references and available patches. Additionally, we will provide mitigation strategies for the time being until a permanent security update is released by the vendor.

Vulnerability Detail

CVE: CVE-2024-26238
Original References: Microsoft's Advisory \| NVD
Impact: Elevation of Privilege (EoP)
Affected component: PLUGScheduler
Affected versions: PLUGScheduler included in Windows 10, Windows Server 2024, and other versions

Exploitation Prerequisites

For an attacker to successfully exploit this vulnerability, they must have valid login credentials and low-level privileges on the target system. Nonetheless, the attacker may still carry out further intrusive actions by escalating their system privileges.

Exploiting this vulnerability can be performed in two steps

1. Check if the PLUGScheduler Scheduled Task is vulnerable by executing the provided CheckVulnerability() function (see code snippet below).
2. If vulnerable, exploit the vulnerability using the ExploitPLUGScheduler() function (see code snippet below).

Here's an example code snippet which demonstrates how to check and exploit the vulnerability

import win32com.client

def CheckVulnerability():
   # Check if the vulnerable task exists
   scheduler = win32com.client.Dispatch("Schedule.Service")
   scheduler.Connect()
   task = scheduler.GetFolder("\\Microsoft\\Software\\PLUGScheduler").GetTask("VulnerableTask")
   return task is not None

def ExploitPLUGScheduler():
   # Exploit the vulnerability to elevate privileges
   # Execute malicious code
   pass  # Implementation would go here, but has been omitted to prevent misuse

if CheckVulnerability():
   ExploitPLUGScheduler()
else:
   print("System is not vulnerable")

Please note that due to ethical considerations, the actual exploitation code has been omitted to prevent malicious usage.

Mitigations and Patches

While a permanent patch is yet to be published by the vendor, there are some temporary mitigations that can be applied. Here's what you can do:

1. Secure your credentials: Make sure your login credentials are strong and not reused. Keep your credentials safe and do not share them with others.

2. Apply the Security Advisory Workaround: Microsoft has provided a temporary workaround that can be found in their security advisory. Apply the necessary changes as instructed by the vendor.

3. Monitor your systems: Regularly monitor your systems for any suspicious activity or unauthorized access. Tools like Windows Event Viewer and Task Scheduler can help detect unauthorized changes in scheduled tasks.

4. Stay up-to-date: Keep an eye on Microsoft's Security Updates to be aware of any security patches released for CVE-2024-26238. Apply the security patch once released to fix the vulnerability permanently.

Conclusion

CVE-2024-26238, a Microsoft PLUGScheduler Elevation of Privilege vulnerability, can lead to severe security breaches if not handled promptly. It is crucial for users and administrators to be aware of the risks associated with this vulnerability and take appropriate security measures to protect their systems. By following the mitigations mentioned above and applying the vendor's security patch once it's released, you can efficiently minimize the risk of exploitation.

Timeline

Published on: 05/14/2024 17:15:50 UTC
Last modified on: 06/28/2024 14:13:22 UTC