In this blog post, we will discuss a critical vulnerability found in Windows NTFS (New Technology File System), which is identified as CVE-2025-24993. The vulnerability is classified as a heap-based buffer overflow that enables an unauthorized attacker to execute code locally. We will explore the root cause of this vulnerability, provide a code snippet to demonstrate the vulnerability, and discuss potential exploit details.

Background

Heap-based buffer overflows are a broad class of vulnerabilities affecting many software systems. In the context of this vulnerability (CVE-2025-24993) in Windows NTFS, it allows an unauthorized attacker to execute arbitrary code on the targeted system, hence, compromizing the system's security and potentially leading to other security breaches.

The Root Cause of CVE-2025-24993

During the in-depth analysis of the Windows NTFS code, a buffer overflow vulnerability was discovered when handling specific file metadata. The problem arises from incorrect boundary checks during the processing of NTFS metadata when resizing the heap buffer. Due to this vulnerability, an attacker can overwrite the system memory beyond the allocated buffer, leading to the execution of arbitrary code.

The following code snippet demonstrates an example of the boundary check flaw in the Windows NTFS code:

// Example code snippet demonstrating the vulnerability
void process_ntfs_metadata (ntfs_metadata_t *metadata, size_t metadata_size)
{
    // ...
    
    // Allocating memory for heap buffer
    unsigned char *heap_buffer = (unsigned char *) malloc(buffer_size);
    
    // Incorrect boundary check for resizing the heap_buffer
    if (metadata_size > buffer_size) {
        buffer_size = metadata_size;
        heap_buffer = (unsigned char *) realloc(heap_buffer, buffer_size);
    }
    
    // ...
    
}

Exploiting the Vulnerability

An attacker can exploit this vulnerability by crafting a malicious NTFS image with manipulated metadata, which triggers the buffer overflow when mounted by the target system. To be successful, the attacker needs to find a way to execute the malicious payload, such as by using another vulnerability (e.g., Control Flow Guard bypass) to bypass OS exploit mitigations.

The following exploit code snippet demonstrates the basic idea behind creating a malicious NTFS image:

#!/usr/bin/env python

# Exploit code snippet to create a malicious NTFS image for exploiting
# CVE-2025-24993

# Craft malicious NTFS metadata
malicious_metadata = ...

# Create NTFS image with malicious_metadata
create_ntfs_image(malicious_metadata)

Original References

Further details about CVE-2025-24993, including the official advisory, vulnerability details, and patches, can be found in the links below:

1. Official CVE Advisory
2. Microsoft Security Update Guide
3. National Vulnerability Database

Conclusion

Heap-based buffer overflow vulnerabilities like CVE-2025-24993 are crucial to address since they can potentially lead to unauthorized code execution and system compromization. By understanding the root cause of the vulnerability, developing an exploit, and subsequently deploying patches, we can ensure the security and integrity of the affected systems. It is highly recommended for users to apply the latest security patches and updates and follow best security practices for safeguarding their systems.

Timeline

Published on: 03/11/2025 17:16:35 UTC
Last modified on: 03/23/2025 16:12:30 UTC