CVE-2024-20653: Microsoft Common Log File System Elevation of Privilege Vulnerability

Overview

The Common Vulnerabilities and Exposures (CVE) system has recorded a new vulnerability, tagged as CVE-2024-20653, which affects Microsoft’s Common Log File System (CLFS). This vulnerability allows malicious actors to escalate their privileges, potentially leading to system compromise or data leakage. In the world of cybersecurity, such vulnerabilities pose a significant threat, particularly to businesses and organizations running the affected versions of Microsoft’s software. Understanding the nature of this vulnerability, its potential impact, and the appropriate mitigation steps is crucial for IT and cybersecurity professionals.

Vulnerability Summary

CVE ID: CVE-2024-20653
Severity: High (7.8 CVSS score)
Attack Vector: Local
Privileges Required: Low
User Interaction: Required
Impact: Elevation of privilege leading to potential system compromise or data leakage

Affected Products

Product | Affected Versions

Microsoft Windows Server | 2012, 2016, 2019
Microsoft Windows | 8, 8.1, 10

How the Exploit Works

The exploit takes advantage of a flaw in the Microsoft’s Common Log File System (CLFS). An attacker who successfully exploited this vulnerability could run arbitrary code in kernel mode. For example, an attacker could then install programs; view, change, or delete data; or create new accounts with full user rights.
To exploit this vulnerability, an attacker would first have to log on to the system. An attacker could then run a specially crafted application that could exploit the vulnerability and take control of an affected system.

Conceptual Example Code

The following pseudocode illustrates a concept of how the vulnerability might be exploited:

#include <windows.h>
int exploit_CLFS_vulnerability() {
HANDLE hDevice = CreateFileA("\\\\.\\CLFS", GENERIC_READ | GENERIC_WRITE, 0, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
if (hDevice == INVALID_HANDLE_VALUE) {
return 1;
}
BYTE payload[0x1000] = { /* malicious payload here */ };
DWORD bytesReturned;
BOOL result = DeviceIoControl(hDevice, IOCTL_CODE, payload, sizeof(payload), NULL, 0, &bytesReturned, NULL);
CloseHandle(hDevice);
if (!result) {
return 1;
}
/* If successful, the attacker now has kernel-level privileges */
return 0;
}

This hypothetical example assumes the attacker has access to the system and can run arbitrary code. The code attempts to open the CLFS device and send a malicious payload via the `DeviceIoControl` function, which if successful, allows the attacker to run code with kernel-level privileges.
Please note that this is a conceptual example and does not reflect a real-world exploit.

Mitigation Guidance

The primary recommended mitigation strategy is to apply security patches provided by Microsoft. If patches cannot be applied immediately, measures such as using a Web Application Firewall (WAF) or Intrusion Detection System (IDS) can serve as temporary mitigations. It’s also crucial to limit the ability of untrusted users to execute code on affected systems as much as possible.