CVE-2024-11797

Executive Summary

CVE-2024-11797 is a critical out-of-bounds write vulnerability in Fuji Electric Monitouch V-SFT, specifically within the parsing of V8 files. This flaw allows remote attackers to execute arbitrary code on affected installations, but requires user interaction (e.g., visiting a malicious page or opening a malicious file). The vulnerability stems from improper validation of user-supplied data, leading to a write past the end of an allocated buffer. With a CVSS score of 7.8, this vulnerability poses a significant risk to industrial control systems (ICS) and operational technology (OT) environments where Monitouch V-SFT is used for HMI (Human-Machine Interface) configuration.

The vulnerability was reported via the Zero Day Initiative (ZDI-CAN-24662) and currently has no known patch or public exploit code. The EPSS score is 0.0%, indicating low exploitation activity in the wild, but the potential for targeted attacks remains high due to the critical nature of the affected systems.

CVSS Breakdown & Threat Level

• CVSS Score: 7.8 (High)
• Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
• Attack Vector (AV): Local (L) – Exploitation requires local access or user interaction.
• Attack Complexity (AC): Low (L) – No special conditions required.
• Privileges Required (PR): None (N) – No authentication needed.
• User Interaction (UI): Required (R) – Victim must open a malicious file or visit a malicious page.
• Scope (S): Unchanged (U) – Vulnerability does not affect other components.
• Confidentiality (C): High (H) – Full data compromise possible.
• Integrity (I): High (H) – Full data modification possible.
• Availability (A): High (H) – Full system denial of service possible.

Threat Level: High. While the EPSS score is low, the impact on ICS/OT environments is severe. An attacker could gain code execution in the context of the current process, potentially leading to full system compromise and disruption of industrial operations.

Deep Dive & Mechanics

The vulnerability exists in the parsing logic of V8 files within Fuji Electric Monitouch V-SFT. V8 files are project files used by the Monitouch V-SFT software for HMI configuration. The specific flaw is an out-of-bounds write (CWE-787) that occurs when the software fails to validate the size of user-supplied data before writing it to a buffer.

Technical Breakdown:

1. Trigger: The vulnerability is triggered when a user opens a specially crafted V8 file (or visits a malicious page that triggers file download and opening).
2. Root Cause: The software does not properly check the length of data read from the V8 file. When parsing a specific field or structure, it writes data beyond the allocated buffer boundary.
3. Exploitation: An attacker can craft a V8 file with oversized data in a specific field. When the software parses this field, it writes past the end of the buffer, corrupting adjacent memory. This can be leveraged to overwrite critical data structures (e.g., function pointers, return addresses) to achieve arbitrary code execution.
4. Impact: Successful exploitation allows the attacker to execute arbitrary code in the context of the Monitouch V-SFT process. This could lead to full system compromise, including access to HMI configurations, control logic, and potentially the underlying OT network.

Vulnerable vs. Patched Code

Since no patch is currently available, a direct comparison is not possible. However, based on the vulnerability description, the vulnerable code likely resembles:

// Vulnerable code example (conceptual)
void parse_v8_field(char *buffer, size_t buffer_size, char *input_data, size_t input_len) {
    // No validation of input_len against buffer_size
    memcpy(buffer, input_data, input_len); // Out-of-bounds write if input_len > buffer_size
}

A patched version would include bounds checking:

// Patched code example (conceptual)
void parse_v8_field(char *buffer, size_t buffer_size, char *input_data, size_t input_len) {
    if (input_len > buffer_size) {
        // Handle error, truncate, or reject
        return;
    }
    memcpy(buffer, input_data, input_len);
}

Exploitation & Lab Setup

Red Team (Exploitation)

Lab Setup:

• Target: Windows 10/11 with Fuji Electric Monitouch V-SFT (vulnerable version) installed.
• Attacker: Kali Linux or any system with a Python environment.
• Tools: Python 3, pwntools (optional), a debugger (x64dbg or WinDbg).

Exploitation Steps:

1. Craft Malicious V8 File: Create a V8 file with a specially crafted field that triggers the out-of-bounds write. This requires reverse engineering the V8 file format to identify the vulnerable field.
2. Deliver Payload: Host the malicious file on a web server or send it via email. Convince the target to open the file.
3. Trigger Vulnerability: When the target opens the file in Monitouch V-SFT, the out-of-bounds write occurs.
4. Achieve Code Execution: Overwrite a function pointer or return address to redirect execution to shellcode. For example, use a ROP chain to bypass DEP/ASLR.

Example Python script to generate a malicious V8 file (conceptual):

import struct

# Craft a malicious V8 file
def create_malicious_v8():
    # Placeholder for actual V8 file structure
    header = b"\x56\x38\x00\x00"  # V8 magic bytes
    # Vulnerable field with oversized data
    payload = b"A" * 1000  # Trigger out-of-bounds write
    # Additional fields to control execution
    rop_chain = struct.pack("<Q", 0x4141414141414141)  # Example ROP gadget
    malicious_file = header + payload + rop_chain
    with open("malicious.v8", "wb") as f:
        f.write(malicious_file)

create_malicious_v8()

Note: No public exploit code is available. The above is a conceptual example.

Blue Team (Detection & Defense)

Detection:

• Monitor for unusual file operations involving V8 files.
• Use endpoint detection and response (EDR) tools to detect out-of-bounds write attempts.
• Deploy application whitelisting to prevent unauthorized execution of Monitouch V-SFT.

Defense:

• Restrict user permissions to prevent opening untrusted files.
• Use sandboxing or virtualization for HMI configuration software.
• Implement network segmentation to isolate OT environments.

Indicators of Compromise (IOCs)

• File Hashes: (None available, but monitor for suspicious V8 files)
• Network Indicators: Connections to known malicious IPs or domains hosting V8 files.
• Process Behavior: Monitouch V-SFT process (e.g., V-SFT.exe) exhibiting abnormal memory access patterns.
• Registry/File System: Creation of unexpected files in temporary directories.
• YARA Rule: (See Detection Engineering)

Detection Engineering

YARA Rule

rule CVE_2024_11797_Malicious_V8 {
    meta:
        description = "Detects malicious V8 files exploiting CVE-2024-11797"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-11797"
    strings:
        $v8_magic = { 56 38 00 00 }  // V8 magic bytes
        $suspicious_size = { FF FF FF FF }  // Example oversized field marker
    condition:
        $v8_magic at 0 and #suspicious_size > 0
}

Sigma Rule

title: CVE-2024-11797 - Fuji Electric Monitouch V-SFT Out-of-Bounds Write
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects exploitation attempts of CVE-2024-11797 via malicious V8 files
author: Valters IT
date: 2025-04-10
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith: '\V-SFT.exe'
        CommandLine|contains: '.v8'
    condition: selection
falsepositives:
    - Legitimate use of V8 files by authorized users
level: high

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2024-11797 - Potential V8 File Download"; flow:to_server,established; content:"|56 38 00 00|"; depth:4; classtype:attempted-user; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Isolate Affected Systems: Disconnect Monitouch V-SFT systems from untrusted networks.
2. User Awareness: Train users not to open V8 files from untrusted sources.
3. Application Control: Use application whitelisting to prevent unauthorized execution.

Long-Term Fixes:

• Patch: Await an official patch from Fuji Electric. Monitor their security advisories.
• Workaround: If possible, use alternative HMI configuration software or restrict file parsing capabilities.
• Network Segmentation: Implement strict network segmentation between IT and OT environments.

Valters IT Signature

This report was generated by Valters IT DevSecOps AI. For questions, contact security@valters-it.com.