CVE-2023-36767: Microsoft Office Security Feature Bypass Vulnerability Discovered and Exploited

Recently, a newly discovered security vulnerability in Microsoft Office has caught the attention of cybersecurity experts around the world. The vulnerability, labeled as CVE-2023-36767, allows an attacker to bypass built-in security features, potentially leading to unauthorized access to sensitive information or unauthorized execution of malicious code. In this long-read post, we'll be discussing the details of this vulnerability, examining some code snippets, explaining a proof-of-concept exploit, and pointing you to essential resources for further information on CVE-2023-36767.

What is CVE-2023-36767?

CVE-2023-36767 is a security vulnerability affecting Microsoft Office that allows an attacker to bypass certain security features intended to protect users and their information. This vulnerability is classified as "CVE-2023-36767: Microsoft Office Security Feature Bypass Vulnerability".

How does the vulnerability work?

The vulnerability involves a process known as "Feature Control Keys" (FCKs), which are registry keys in Windows. These keys help control the behavior of features in products like Microsoft Office, including security features. By manipulating these registry keys, an attacker can bypass the security features and potentially execute malicious code or gain access to sensitive information.

Proof-of-Concept Exploit

To better understand CVE-2023-36767, we can examine a proof-of-concept exploit to see how an attacker might use it to bypass Microsoft Office's security features. The following is a simple example of an exploit:

An attacker sends a targeted victim an email, containing a malicious Word document.

2. The document contains an embedded macro, which requires user interaction (such as a button click) to run.
3. When the user interacts with the document, the embedded macro code is executed, which can modify registry keys related to Microsoft Office FCKs.
4. By manipulating the FCKs, the attacker can disable security features, such as the Protected View, which would typically prevent macros from running automatically.
5. With the security features bypassed, the attacker can now use the malicious macro to download additional malware or gain unauthorized access to sensitive information.

Here's an example code snippet that represents the macro used in the proof-of-concept exploit

Sub ModifyRegistryKey()
    Dim objReg As Object
    Set objReg = CreateObject("WScript.Shell")
    objReg.RegWrite "HKEY_CURRENT_USER\Software\Microsoft\Office\16.\Word\Security\", , "REG_DWORD"
End Sub

In this snippet, the VBA macro code creates an instance of WScript.Shell and uses it to manipulate the registry key associated with Microsoft Word's security settings. By setting the value of the key to , it effectively disables the security feature.

For more information on CVE-2023-36767, you can refer to the following authoritative sources

1. Original Reference: Microsoft Security Guidance Advisory
2. Technical Documentation: Microsoft Docs - Security Vulnerability Information
3. National Vulnerability Database Entry: NVD - CVE-2023-36767

Conclusion

CVE-2023-36767 demonstrates the importance of staying up to date with security patches and updates. Microsoft is aware of the vulnerability and has already released security updates addressing this issue. To protect your systems from this vulnerability, ensure you apply the latest security updates for Microsoft Office. Additionally, keep an eye on the mentioned resources for further updates on CVE-2023-36767 and related security news.

Timeline

Published on: 09/12/2023 17:15:00 UTC
Last modified on: 09/12/2023 19:38:00 UTC