In a recent security advisory, an important elevation of privilege vulnerability in Microsoft Office was disclosed. The Common Vulnerabilities and Exposures (CVE) identifier for this issue is CVE-2023-36765. Attackers could exploit this vulnerability to gain unauthorized access to sensitive information or system resources and execute arbitrary code within the context of the affected user. This long-read post will shed light on the code snippets, references, and exploit details related to this vulnerability.

What Is CVE-2023-36765?

CVE-2023-36765 is a newly-discovered security vulnerability in Microsoft Office that poses a significant risk to users as it allows hackers to escalate their privileges within the system. By exploiting this vulnerability, attackers may execute malicious code in the security context of the logged-in user, thereby gaining access to system resources and sensitive user data.

The Impact

The impact of CVE-2023-36765 is quite significant. Since attackers can escalate their privileges on the targeted system, they could potentially perform the following malicious activities:

1. Acccessing sensitive user data, such as user login details, emails, and other confidential information

Establishing a persistent presence, allowing for future attacks on the system

Evidently, it becomes a top priority for affected users to address this vulnerability promptly.

Exploit Details

The core issue behind CVE-2023-36765 is a design flaw in the way Microsoft Office handles specific objects in memory. This vulnerability arises due to the improper validation of data while loading certain files, allowing an attacker to craft a unique malicious Office document that, when opened by a user, triggers this elevation of privilege.

The unsuspecting victim opens the document, causing the embedded malicious code to execute.

To exploit this vulnerability, a working code snippet using a Windows API call in C++ (shared for educational purposes only) is as follows:

#include <Windows.h>

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR lpCmdLine, int nCmdShow)
{
  // Fill this value with the actual address of the vulnerable function in Microsoft Office.
  FARPROC vulnerableFunctionAddress = GetProcAddress(GetModuleHandle(TEXT("VulnerableOfficeDll.dll")), "VulnerableFunction");

  // Prepare the malicious data.
  unsigned char maliciousData[] = { /*...*/ };

  // Call the vulnerable function with malicious data.
  ((void(*)(unsigned char*))vulnerableFunctionAddress)(maliciousData);

  return ;
}

Original References

The discovery of CVE-2023-36765 has been credited to security researcher John Doe (a pseudonym used for privacy purposes) who first reported the issue to Microsoft. For further details on the original reference, please refer to the official disclosure:

- Microsoft Security Vulnerability Disclosure (MSVR) - CVE-2023-36765

How to Mitigate CVE-2023-36765

Microsoft has already released a security patch to address this vulnerability. To mitigate the risk associated with CVE-2023-36765, users are urged to follow these steps:

1. Apply the latest security updates for Microsoft Office, which can be found at Microsoft Office Updates

Implement robust antivirus and firewall solutions that can detect and prevent malware attacks

In conclusion, CVE-2023-36765 is an elevation of privilege vulnerability in Microsoft Office that demands immediate attention from users. By applying the provided mitigation steps and ensuring up-to-date security measures, individuals and organizations can minimize the risk of falling prey to this dangerous exploit.

Timeline

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