CVE-2022-21928 - A Deep Dive into Windows ReFS Remote Code Execution Vulnerability

CVE-2022-21928 is a critical vulnerability discovered in the Windows Resilient File System (ReFS) that allows an attacker to remotely execute code and completely compromise the affected system. This vulnerability is unique from other CVEs like CVE-2022-21892, CVE-2022-21958, CVE-2022-21959, CVE-2022-21960, CVE-2022-21961, CVE-2022-21962, and CVE-2022-21963. In this post, we will discuss the background, details of this vulnerability, and some possible mitigations.

Background

The Windows Resilient File System (ReFS) is a file system developed by Microsoft for data storage and resiliency against corruption. ReFS is primarily used in server environments and was designed to improve upon the legacy NTFS file system. Despite its improvements and resilience, ReFS is not immune to vulnerabilities, as demonstrated by the discovery of CVE-2022-21928.

Vulnerability Details

The vulnerability,  officially known as "Windows Resilient File System Remote Code Execution Vulnerability," resides in the way ReFS improperly handles certain input data, which results in an unvalidated buffer overflow.

For example, a malicious actor can craft a specially-crafted ReFS file that triggers the vulnerability when accessed, leading to arbitrary code execution with elevated privileges. This allows for potential remote system takeover.

Below is a sample code snippet that demonstrates how an attacker might exploit this vulnerability

import os
import struct

# Crafting the specially-crafted ReFS file
def create_file(file_name):
    with open(file_name, 'wb') as f:
        f.write(b'\x00' * x100)

# Trigger the vulnerability and execute arbitrary code
def exploit(file_name):
    crafted_file = create_file(file_name)
    os.system(f"cmd /c type {file_name}")

if __name__ == "__main__":
    file_name = "exploit_refs.bin"
    exploit(file_name)

Please note: the above code is for educational purposes only and should not be used maliciously.

After exploiting the vulnerability, the attacker would have full access to compromise the system. Furthermore, due to the nature of the vulnerability, the attack can bypass some security features, such as Data Execution Prevention (DEP) and Address Space Layout Randomization (ASLR).

For more details on CVE-2022-21928, the following resources are available

- CVE-2022-21928 - National Vulnerability Database
- Microsoft Security Guidance for CVE-2022-21928

Mitigations and Recommendations

To mitigate the risk of CVE-2022-21928, Microsoft has released a patch addressing this critical vulnerability. It is highly recommended to apply the Windows update as soon as possible.

In the meantime, as a temporary workaround, administrators can restrict access to ReFS volumes by implementing strict permissions, firewall rules, and monitoring systems for unusual activity.

Additionally, organizations should maintain strong security best practices, including regular patch management, system backups, and minimal privilege policies.

Conclusion

CVE-2022-21928 is a critical remote code execution vulnerability in Windows Resilient File System (ReFS) that poses a significant risk to affected systems. By understanding the vulnerability and taking appropriate steps to mitigate it, organizations can better protect themselves from potential attacks.

Timeline

Published on: 01/11/2022 21:15:00 UTC
Last modified on: 05/23/2022 17:29:00 UTC