CVE-2024-11800

Executive Summary

CVE-2024-11800 is a critical stack-based buffer overflow vulnerability in Fuji Electric Tellus Lite V-Simulator 5, specifically during the parsing of V8 files. The flaw allows remote attackers to execute arbitrary code in the context of the current process, but requires user interaction (opening a malicious file or visiting a malicious page). With a CVSS score of 7.8, this vulnerability poses a significant risk to industrial control system (ICS) environments where Tellus Lite is used for HMI simulation. No public exploit code or patch is currently available, making detection and mitigation critical.

CVSS Breakdown & Threat Level

• CVSS Score: 7.8 (High)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: Required (victim must open a malicious file or page)
• Scope: Unchanged
• Confidentiality Impact: High
• Integrity Impact: High
• Availability Impact: High
• Threat Level: High – Exploitation could lead to full compromise of the affected system, potentially enabling lateral movement within OT networks.

Deep Dive & Mechanics

The vulnerability resides in the V-Simulator 5 component of Fuji Electric Tellus Lite, which parses V8 files. The specific flaw is a classic stack-based buffer overflow (CWE-121) caused by insufficient validation of user-supplied data length before copying it to a fixed-length stack buffer. When a specially crafted V8 file is opened, the program copies data beyond the buffer’s capacity, overwriting adjacent memory on the stack. This can corrupt the return address or other critical data, allowing an attacker to hijack execution flow and achieve arbitrary code execution.

The attack surface is user-initiated: the victim must be tricked into opening a malicious V8 file (e.g., via phishing email or malicious website). Once executed, the payload runs with the privileges of the current user, which in many ICS environments may be elevated.

Vulnerable vs. Patched Code

Since no patch is available, a direct code comparison cannot be provided. However, the vulnerable code pattern is typical of unsafe string copy functions (e.g., strcpy, memcpy without bounds checking) in C/C++ when parsing file data. A patched version would implement proper length validation, such as using strncpy or snprintf, and ensure that buffer sizes are checked before copying.

Vulnerable Code Pattern (Hypothetical):

char buffer[256];
// No length check
strcpy(buffer, user_input_from_file);

Patched Code Pattern (Hypothetical):

char buffer[256];
// Length check
if (strlen(user_input_from_file) < sizeof(buffer)) {
    strcpy(buffer, user_input_from_file);
} else {
    // Handle error
}

Exploitation & Lab Setup

Red Team (Exploitation)

No public exploit code is available. However, a typical exploitation approach would involve:

1. Crafting a Malicious V8 File: Create a V8 file with a payload that overflows the stack buffer. The payload should include shellcode and a ROP chain to bypass modern mitigations (e.g., ASLR, DEP).
2. Delivery: Use social engineering (e.g., phishing email with attachment) to deliver the file to the victim.
3. Trigger: The victim opens the file in Tellus Lite V-Simulator 5, triggering the overflow and executing the payload.

Lab Setup:

• Target: Windows machine with Fuji Electric Tellus Lite V-Simulator 5 installed.
• Tools: Immunity Debugger, Mona.py, Metasploit (for payload generation), custom Python script to craft V8 file.
• Steps:
  1. Install the vulnerable software.
  2. Generate a malicious V8 file using a fuzzer or manual crafting.
  3. Attach debugger to the V-Simulator process.
  4. Open the file and observe the crash.
  5. Develop an exploit to achieve code execution.

Blue Team (Defense)

• Detection: Monitor for unusual file opens (V8 files) and process crashes. Use the YARA and Sigma rules below.
• Prevention: Restrict execution of Tellus Lite to authorized users only. Use application whitelisting. Disable unnecessary file associations.
• Mitigation: If possible, isolate the system from the internet and untrusted networks. Use network segmentation to limit lateral movement.

Indicators of Compromise (IOCs)

• File Hashes: (No known samples; monitor for suspicious V8 files)
• Network Indicators: Outbound connections from the Tellus Lite process to unknown IPs (post-exploitation C2).
• Process Anomalies: Unexpected child processes spawned by VSimulator5.exe or TellusLite.exe.
• Registry/File System: Creation of new files in temporary directories or startup folders.
• Memory Artifacts: Stack corruption patterns, unusual memory allocations.

Detection Engineering

YARA Rule

rule CVE_2024_11800_V8_Overflow {
    meta:
        description = "Detects malicious V8 files targeting CVE-2024-11800"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-11800"
    strings:
        $magic = { 56 38 46 49 4C 45 } // "V8FILE" magic bytes (hypothetical)
        $overflow_pattern = { 41 41 41 41 41 41 41 41 } // Pattern of 'A's indicating overflow
    condition:
        $magic at 0 and #overflow_pattern > 10
}

Sigma Rule

title: Suspicious V8 File Open by Tellus Lite
id: 8f7b3c2a-1d4e-5f6a-7b8c-9d0e1f2a3b4c
status: experimental
description: Detects attempts to open V8 files that may exploit CVE-2024-11800
author: Valters IT
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith: 'VSimulator5.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-2024-11800 Potential Exploit Delivery"; flow:to_server,established; content:"V8FILE"; offset:0; depth:6; content:"|41 41 41 41 41 41 41 41|"; distance:0; within:100; classtype:attempted-user; sid:1000001; rev:1;)

Remediation & Mitigation

• Immediate: Disable or uninstall Tellus Lite V-Simulator 5 if not essential. Restrict user permissions to prevent execution.
• Workaround: Use file reputation services to block unknown V8 files. Implement strict email filtering for attachments.
• Long-term: Monitor vendor for patches. Consider migrating to alternative HMI simulation tools with active security support.
• Network: Segment OT networks from IT and internet. Use IDS/IPS with the Suricata rule above.

Valters IT
Senior DevSecOps & Cyber Threat Intelligence Expert