CVE-2024-11799

Executive Summary

CVE-2024-11799 is a critical stack-based buffer overflow vulnerability in Fuji Electric Tellus Lite V-Simulator 5. The flaw resides in the parsing of V8 files, allowing remote attackers to execute arbitrary code in the context of the current process. User interaction is required, as the target must open a malicious V8 file or visit a malicious page. The vulnerability has a CVSS score of 7.8 (High) and is currently unpatched. No public proof-of-concept (PoC) or exploit code is available at this time.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
• Base Score: 7.8 (High)
• Attack Vector: Network (AV:N)
• Attack Complexity: Low (AC:L)
• Privileges Required: None (PR:N)
• User Interaction: Required (UI:R)
• Scope: Unchanged (S:U)
• Confidentiality Impact: High (C:H)
• Integrity Impact: High (I:H)
• Availability Impact: High (A:H)

The threat level is high due to the potential for remote code execution with no privileges required, although user interaction is necessary.

Deep Dive & Mechanics

The vulnerability is a classic stack-based buffer overflow (CWE-121) in the V-Simulator 5 component of Fuji Electric Tellus Lite. When parsing a specially crafted V8 file, the software fails to validate the length of user-supplied data before copying it to a fixed-length stack buffer. This allows an attacker to overwrite the stack, including the return address, leading to arbitrary code execution.

The attack vector is remote, but user interaction is required—the victim must open a malicious V8 file or visit a malicious page that triggers the file parsing. The exploit runs in the context of the current user process, meaning it inherits the user's privileges.

Vulnerable vs. Patched Code

Since no patch is available, a direct code comparison cannot be made. However, the vulnerable code likely resembles:

void parse_v8_file(char *data) {
    char buffer[256];
    strcpy(buffer, data); // No bounds checking
}

A patched version would use safe functions like strncpy or check the length before copying:

void parse_v8_file(char *data) {
    char buffer[256];
    if (strlen(data) < sizeof(buffer)) {
        strcpy(buffer, data);
    } else {
        // Handle error
    }
}

Exploitation & Lab Setup

Red Team

Lab Setup:

1. Install Fuji Electric Tellus Lite V-Simulator 5 on a Windows VM.
2. Create a malicious V8 file with a payload that triggers the buffer overflow.
3. Use a debugger (e.g., WinDbg) to identify the offset to the return address.

Exploit Development:

• Craft a V8 file with a long string to overflow the buffer.
• Use a pattern to find the exact offset to overwrite the return address.
• Replace the return address with the address of a shellcode or ROP chain.

Example Payload (Conceptual):

# Python script to generate malicious V8 file
payload = b"A" * 256  # Fill buffer
payload += b"B" * 8   # Overwrite saved EBP
payload += b"C" * 8   # Overwrite return address (to be replaced with shellcode address)
# Add shellcode after the return address
payload += b"\x90" * 16  # NOP sled
payload += shellcode
with open("malicious.v8", "wb") as f:
    f.write(payload)

Delivery: Host the file on a malicious website or send via email.

Blue Team

Detection:

• Monitor for unusual V8 file sizes or patterns.
• Use endpoint detection and response (EDR) to detect stack-based buffer overflow attempts.
• Enable ASLR and DEP to mitigate exploitation.

Hunting:

• Search for processes (e.g., VSimulator5.exe) crashing with access violations.
• Look for suspicious child processes spawned by the V-Simulator.

Indicators of Compromise (IOCs)

• File Hashes: (No known samples yet)
• Network Indicators: Connections to malicious IPs hosting the exploit.
• Process Indicators: VSimulator5.exe crashing or spawning cmd.exe or powershell.exe.
• Registry Keys: (None specific)
• YARA Rule: See Detection Engineering.

Detection Engineering

YARA Rule

rule CVE_2024_11799_V8_Overflow {
    meta:
        description = "Detects malicious V8 files exploiting CVE-2024-11799"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-11799"
    strings:
        $magic = { 56 38 00 } // "V8" magic bytes
        $long_string = /.{512,}/ // Files with long strings
    condition:
        $magic at 0 and #long_string > 0
}

Sigma Rule

title: CVE-2024-11799 Exploitation Attempt
id: 8f4b3c2a-1d5e-4f7b-9a0c-3e6d8f2b1a4c
status: experimental
description: Detects potential exploitation of CVE-2024-11799 via V8 file parsing
author: Valters IT
date: 2025-04-10
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith: '\VSimulator5.exe'
        CommandLine|contains: '.v8'
    condition: selection
falsepositives:
    - Legitimate use of V8 files
level: high

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2024-11799 V8 File Download"; flow:to_server,established; content:"|56 38|"; depth:2; content:".v8"; nocase; classtype:attempted-user; sid:1000001; rev:1;)

Remediation & Mitigation

• Immediate: Disable the V-Simulator 5 component if not needed.
• User Awareness: Train users not to open untrusted V8 files or visit suspicious pages.
• Network Controls: Block downloads of .v8 files from untrusted sources.
• Patch: Await an official patch from Fuji Electric. Monitor their security advisories.
• Workaround: Use application whitelisting to prevent unauthorized executables.

Valters IT
Securing Digital Frontiers