CVE-2024-11803

Executive Summary

CVE-2024-11803 is a critical out-of-bounds write vulnerability in Fuji Electric Tellus Lite V-Simulator 5, specifically during the parsing of V8 files. This flaw allows remote code execution in the context of the current process, requiring 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 currently unpatched. No public exploit code or proof-of-concept is available, but the risk is elevated due to the lack of a vendor patch.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby ecosystems. It affects a proprietary industrial control system (ICS) software component from Fuji Electric.

CVSS Breakdown & Threat Level

• CVSS Score: 7.8 (High)
• Attack Vector: Local (requires user interaction)
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: Required
• Scope: Unchanged
• Confidentiality Impact: High
• Integrity Impact: High
• Availability Impact: High

Threat Level: High. Exploitation could lead to full system compromise within the user’s session, potentially enabling lateral movement in OT/ICS environments.

Deep Dive & Mechanics

The vulnerability resides in the V-Simulator 5 component of Fuji Electric Tellus Lite, which is used for simulating and visualizing industrial automation processes. The flaw occurs during the parsing of specially crafted V8 files. The software fails to validate user-supplied data properly, leading to a write past the end of an allocated buffer (out-of-bounds write). This memory corruption can be leveraged by an attacker to execute arbitrary code.

Root Cause: Lack of bounds checking when processing V8 file data, allowing an attacker to overwrite adjacent memory regions.

Attack Vector: Remote, but requires user interaction (e.g., opening a malicious V8 file or visiting a compromised website that triggers file download).

Impact: Successful exploitation grants the attacker code execution in the context of the current user, potentially leading to data theft, system compromise, or further network penetration.

Vulnerable vs. Patched Code

No patched version is available. The vulnerable code is in the V8 file parsing routine. A hypothetical fix would involve adding bounds checks before memory write operations.

Vulnerable Code (Conceptual):

void parse_v8_file(char *data, size_t size) {
    char buffer[256];
    // No bounds check
    memcpy(buffer, data, size); // Out-of-bounds write if size > 256
}

Patched Code (Conceptual):

void parse_v8_file(char *data, size_t size) {
    char buffer[256];
    if (size > sizeof(buffer)) {
        // Handle error
        return;
    }
    memcpy(buffer, data, size);
}

Exploitation & Lab Setup

Red Team

Prerequisites:

• Fuji Electric Tellus Lite V-Simulator 5 installed on a target system.
• Ability to deliver a malicious V8 file (e.g., via phishing email or drive-by download).

Exploitation Steps:

1. Craft a malicious V8 file with a payload that triggers an out-of-bounds write.
2. Deliver the file to the target user.
3. When the user opens the file in V-Simulator 5, the payload executes, granting code execution.

Note: No public exploit code is available. The following is a conceptual example of a malicious V8 file structure (not functional).

# Conceptual exploit generator (not functional)
def generate_malicious_v8():
    payload = b"A" * 300  # Overflow buffer
    # Additional shellcode or ROP chain
    return payload

Blue Team

Detection:

• Monitor for unusual file access patterns involving .v8 files.
• Use endpoint detection and response (EDR) to detect memory corruption events.
• Implement application whitelisting to prevent unauthorized execution of V-Simulator 5.

Hunting:

• Search for processes (e.g., VSimulator5.exe) with high memory usage or crashes.
• Analyze network traffic for suspicious file downloads.

Indicators of Compromise (IOCs)

• File Hashes (SHA256): Unknown (no public samples)
• File Names: *.v8 (malicious files)
• Process Names: VSimulator5.exe
• Network Indicators: Connections to known malicious domains or IPs delivering V8 files.
• Registry Keys: N/A
• YARA Rule: See Detection Engineering.

Detection Engineering

YARA Rule

rule CVE_2024_11803_Malicious_V8 {
    meta:
        description = "Detects malicious V8 files targeting CVE-2024-11803"
        author = "Valters IT"
        date = "2025-04-10"
    strings:
        $magic = { 56 38 00 } // "V8" magic bytes (example)
        $overflow = { 41 41 41 41 } // Pattern of overflow
    condition:
        $magic at 0 and #overflow > 10
}

Sigma Rule

title: CVE-2024-11803 Exploitation Attempt
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects potential exploitation of CVE-2024-11803 via V8 file parsing
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith: 'VSimulator5.exe'
        CommandLine|contains: '.v8'
    condition: selection
falsepositives:
    - Legitimate use of V-Simulator 5 with V8 files
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-11803 - Malicious V8 File Download"; flow:to_client; file.name:/\.v8$/i; content:"V8"; within:4; classtype:attempted-user; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Isolate affected systems: Disconnect Fuji Electric Tellus Lite from production networks if possible.
2. User awareness: Train users not to open untrusted V8 files or visit suspicious websites.
3. Application control: Use software restriction policies to block V-Simulator 5 execution unless absolutely necessary.

Long-term Fix:

• Await an official patch from Fuji Electric. Monitor their security advisories.
• Consider migrating to alternative simulation software if no patch is released.

Workarounds:

• Disable file association for .v8 files.
• Use a sandbox or virtual machine to open V8 files.

Valters IT
Securing Industrial Systems