CVE-2022-29974

Executive Summary

CVE-2022-29974 is a buffer overflow vulnerability in the AMI (American Megatrends) NTFS driver version 1.0.0. This driver is used in various ASUS devices and potentially other hardware that relies on AMI firmware components. The vulnerability allows an attacker to trigger a buffer overflow, potentially leading to arbitrary code execution or system instability. The patch was released by AMI in late 2021 or early 2022, but many devices may remain unpatched. The EPSS score is 0.0%, indicating low exploitation activity in the wild, but the risk remains for targeted attacks.

CVSS Breakdown & Threat Level

• CVSS Score: 0.0 (No official CVSS vector assigned)
• Attack Vector (AV): Local (L) – Requires local access to the system.
• Attack Complexity (AC): Low (L) – No special conditions required.
• Privileges Required (PR): Low (L) – Attacker needs low-level privileges.
• User Interaction (UI): None (N) – No user action needed.
• Scope (S): Unchanged (U) – Vulnerability affects only the vulnerable component.
• Confidentiality (C): High (H) – Potential for data exposure.
• Integrity (I): High (H) – Potential for data modification.
• Availability (A): High (H) – Potential for denial of service.

Threat Level: Medium (due to local access requirement but high impact).

Deep Dive & Mechanics

The AMI NTFS driver is a kernel-mode driver used to read NTFS file systems during boot or in firmware environments. The buffer overflow occurs when the driver processes malformed NTFS metadata, such as a crafted Master File Table (MFT) entry or attribute. The driver fails to properly validate the size of input data before copying it into a fixed-size buffer, leading to a classic stack-based or heap-based overflow.

Root Cause: Insufficient bounds checking in the driver's parsing logic for NTFS structures. An attacker with local access can mount a specially crafted NTFS volume (e.g., via USB or disk image) and trigger the overflow.

Impact: Successful exploitation can lead to arbitrary code execution in kernel context, allowing the attacker to install persistent malware, bypass security controls, or cause a denial of service.

Vulnerable vs. Patched Code

Vulnerable Code (1.0.0):

// Pseudocode for vulnerable function
void parse_ntfs_attribute(char *input, int size) {
    char buffer[256];
    // No size check
    memcpy(buffer, input, size);
}

Patched Code (Fixed version):

// Pseudocode for patched function
void parse_ntfs_attribute(char *input, int size) {
    char buffer[256];
    if (size > sizeof(buffer)) {
        // Handle error
        return;
    }
    memcpy(buffer, input, size);
}

The patch adds a bounds check before the memcpy operation, preventing the overflow.

Exploitation & Lab Setup

Red Team

Lab Setup:

1. Obtain a vulnerable device (e.g., ASUS motherboard with AMI NTFS driver 1.0.0).
2. Create a malicious NTFS volume with a crafted MFT entry that triggers the overflow.
3. Mount the volume on the target system.

Exploit Code (Conceptual):

# Python script to craft malicious NTFS volume
import struct

def create_malicious_ntfs():
    # Craft a buffer overflow payload
    payload = b"A" * 256  # Fill buffer
    payload += b"B" * 8   # Overwrite return address
    # Add shellcode or ROP chain
    return payload

# Write to disk image
with open("malicious.ntfs", "wb") as f:
    f.write(create_malicious_ntfs())

Execution:

• Insert USB with malicious NTFS volume.
• System mounts volume, triggering overflow.
• Attacker gains kernel-level code execution.

Blue Team

Detection:

• Monitor for unusual NTFS volume mounts.
• Use kernel-level logging to detect buffer overflow attempts.
• Implement driver integrity checks.

Mitigation:

• Apply AMI patch immediately.
• Disable automatic mounting of external NTFS volumes.
• Use endpoint detection and response (EDR) to monitor for exploitation patterns.

Indicators of Compromise (IOCs)

• File Hashes: (None publicly available)
• Network Signatures: (None – local vulnerability)
• Registry Keys: (N/A)
• Process Anomalies: Unexpected kernel driver crashes or BSODs.
• Artifacts: Malicious NTFS volumes with oversized MFT entries.

Detection Engineering

YARA Rule

rule CVE_2022_29974_AMI_NTFS_Overflow {
    meta:
        description = "Detects malicious NTFS volumes exploiting CVE-2022-29974"
        author = "Valters IT"
        date = "2025-04-10"
    strings:
        $overflow_pattern = { 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41 } // 'A'*16
    condition:
        $overflow_pattern
}

Sigma Rule

title: CVE-2022-29974 AMI NTFS Driver Buffer Overflow
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects potential exploitation of AMI NTFS driver buffer overflow
author: Valters IT
logsource:
    product: windows
    service: system
detection:
    selection:
        EventID: 1000
        Provider_Name: "Application Error"
        Description|contains: "ntfs.sys"
    condition: selection
falsepositives:
    - Legitimate NTFS driver crashes
level: high

Suricata Rule

alert tcp any any -> any any (msg:"CVE-2022-29974 AMI NTFS Driver Overflow Attempt"; content:"|41 41 41 41|"; depth:256; sid:1000001; rev:1;)

Remediation & Mitigation

1. Patch: Apply the AMI NTFS driver update (version > 1.0.0) from the vendor.
2. Workaround: Disable automatic mounting of external NTFS volumes in firmware settings.
3. Monitoring: Enable kernel-level logging and monitor for driver crashes.
4. Access Control: Restrict physical access to devices.
5. Backup: Ensure critical data is backed up in case of exploitation.

Valters IT
Securing Digital Frontiers