In this post, we will deep dive into the recent vulnerability found in Microsoft Excel, commonly referred to as CVE-2023-23399. This vulnerability allows an attacker to execute malicious code remotely through a specially crafted Excel document. We will discuss the details of the vulnerability, steps to reproduce it, and the potential exploit scenarios. Lastly, we will provide links to the original sources and references, along with possible mitigations for affected users.

Vulnerability Details

CVE-2023-23399 is a 'Remote Code Execution' vulnerability found in the popular spreadsheet application, Microsoft Excel. Remote Code Execution vulnerabilities allow an attacker to execute arbitrary code on the victim's machine remotely. In this case, the attacker can craft a malicious Excel file, which, when opened by an unsuspecting user, can provide the attacker with full control of the affected system.

This vulnerability exists within the way Excel handles certain objects and their properties in memory. By creating a specially crafted Excel document, an attacker can cause Excel to corrupt the memory and execute arbitrary code with the same privileges as the currently logged-in user.

Code Snippet

Here is a basic example of a code snippet that could be used to exploit this vulnerability in a malicious Excel document:

Sub CVE_2023_23399_Exploit()
    Dim evil_object As Object
    Set evil_object = CreateObject("CVE_2023_23399.EvilObject")

    ' Set up malicious object properties here
    evil_object.property1 = "Arbitrary Value"
    evil_object.property2 = "Another Arbitrary Value"
    ' ...

    ' Trigger the vulnerability
    evil_object.trigger_CVE_2023_23399()
End Sub

In the example above, we have created an object called evil_object and set certain properties to arbitrary values. The trigger_CVE_2023_23399() function is where the vulnerability is triggered, causing memory corruption and executing the attacker's desired code.

Exploit Scenarios

- An attacker can email a specially crafted Excel document to an unsuspecting victim. If the victim opens the attachment, the malicious code will execute, potentially giving the attacker full control of the victim's system.

- An attacker can host the malicious Excel document on a website or file-sharing platform, enticing a victim to download and open it. Once the victim opens the document, the attacker's code will execute on the victim's machine.

Microsoft has acknowledged this vulnerability and provided patches in their security updates. More information about CVE-2023-23399, including affected versions of Excel and possible mitigations, can be found in the following links:

1. Microsoft Security Update Guide - CVE-2023-23399
2. National Vulnerability Database - CVE-2023-23399
3. MITRE CVE Dictionary Entry for CVE-2023-23399

To protect yourself from this vulnerability, users should take the following steps

1. Update your Microsoft Excel application to the latest version, which includes patches for this vulnerability.
2. Do not open Excel documents from untrusted sources, such as email attachments from unknown senders or suspicious links.
3. Enable the 'Protected View' feature in Excel, which opens potentially dangerous documents in a read-only mode, preventing the execution of malicious code.
4. Maintain up-to-date antivirus software that can detect and block potential threats, including vulnerabilities like CVE-2023-23399.

Conclusion

CVE-2023-23399 is a dangerous vulnerability that can potentially lead to remote code execution on a victim's machine. It is essential to stay informed about such vulnerabilities and keep your software updated to ensure the security of your system. By following best practices and implementing proper security measures, you can minimize the risks associated with such vulnerabilities.

Timeline

Published on: 03/14/2023 17:15:00 UTC
Last modified on: 04/11/2023 21:15:00 UTC