CVE-2024-11576

Executive Summary

CVE-2024-11576 is a critical heap-based buffer overflow vulnerability in Luxion KeyShot, a professional 3D rendering and animation application. The flaw resides in the parsing of 3DS (3D Studio) files. An attacker can exploit this by convincing a user to open a specially crafted 3DS file, leading to remote code execution in the context of the current process. The vulnerability was reported through the Zero Day Initiative (ZDI-CAN-23681). With a CVSS score of 7.8, it poses a significant risk to users of KeyShot, particularly in design, engineering, and media production environments. No public exploit code or patch is currently available, making user awareness and strict file handling procedures the primary defense.

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) – The attacker must deliver the malicious file to the target system.
• Attack Complexity (AC): Low (L) – No special conditions are required to trigger the overflow.
• Privileges Required (PR): None (N) – No authentication is needed.
• User Interaction (UI): Required (R) – The victim must open the malicious file.
• Scope (S): Unchanged (U) – The vulnerability does not affect other components.
• Confidentiality (C): High (H) – Full data access is possible.
• Integrity (I): High (H) – Arbitrary code execution can modify data.
• Availability (A): High (H) – Code execution can lead to denial of service or system compromise.

Threat Level: High. The vulnerability is exploitable with low complexity and requires only user interaction. In a corporate environment, a single user opening a malicious 3DS file could lead to lateral movement or data exfiltration.

Deep Dive & Mechanics

The vulnerability is a classic heap-based buffer overflow (CWE-122) in the 3DS file parser of Luxion KeyShot. The 3DS file format is a binary format used by Autodesk 3ds Max. The parser fails to validate the length of user-supplied data before copying it to a heap-allocated buffer.

Technical Breakdown:

1. Trigger: The user opens a malicious .3ds file.
2. Parsing: KeyShot’s parser reads a chunk of data from the file, likely a material or mesh data block.
3. Buffer Allocation: A heap buffer is allocated based on a size field in the file header or chunk.
4. Copy Operation: The parser copies the data from the file into the buffer without verifying that the data length does not exceed the allocated buffer size.
5. Overflow: If the data length is larger than the buffer, the copy operation overwrites adjacent heap memory.
6. Code Execution: An attacker can craft the overflow data to overwrite function pointers, exception handlers, or other critical data structures, leading to arbitrary code execution.

Attack Vector: The attacker must deliver the malicious file via email, download, or other means. The victim must open it with KeyShot.

Vulnerable vs. Patched Code

Since no patch is available, a hypothetical fix would involve adding length validation before the copy operation.

Vulnerable Code (Pseudocode):

void parse_3ds_chunk(FILE *file) {
    uint32_t chunk_id;
    uint32_t chunk_length;
    fread(&chunk_id, 4, 1, file);
    fread(&chunk_length, 4, 1, file);
    char *buffer = (char*)malloc(chunk_length);
    // Vulnerable: no check on data size
    fread(buffer, chunk_length, 1, file);
    // Process buffer...
}

Patched Code (Hypothetical):

void parse_3ds_chunk(FILE *file) {
    uint32_t chunk_id;
    uint32_t chunk_length;
    fread(&chunk_id, 4, 1, file);
    fread(&chunk_length, 4, 1, file);
    // Validate chunk length against a maximum allowed size
    if (chunk_length > MAX_CHUNK_SIZE) {
        // Handle error
        return;
    }
    char *buffer = (char*)malloc(chunk_length);
    if (buffer == NULL) {
        // Handle allocation failure
        return;
    }
    size_t bytes_read = fread(buffer, 1, chunk_length, file);
    if (bytes_read != chunk_length) {
        // Handle read error
        free(buffer);
        return;
    }
    // Process buffer...
}

Exploitation & Lab Setup

Red Team

Objective: Achieve remote code execution on a target running Luxion KeyShot.

Lab Setup:

• Attacker Machine: Kali Linux with Metasploit or custom exploit development tools.
• Target Machine: Windows 10/11 with Luxion KeyShot (vulnerable version) installed.
• Network: Isolated lab network.

Exploitation Steps:

1. Craft Malicious 3DS File: Use a hex editor or a custom Python script to create a 3DS file with an oversized chunk. The overflow data should overwrite a function pointer (e.g., a vtable pointer) to redirect execution to shellcode.
2. Deliver File: Send the file via email or host it on a website.
3. Trigger: The victim opens the file in KeyShot.
4. Code Execution: The overflow triggers, and the shellcode executes, providing a reverse shell or other payload.

Example Python Script (Conceptual):

import struct

# Craft a malicious 3DS file
def create_malicious_3ds():
    # 3DS file header (dummy)
    header = b'\x4D\x4D'  # 3DS identifier
    # Main chunk
    chunk_id = 0x3D3D  # 3D Editor chunk
    # Overflow: allocate small buffer but provide large data
    fake_length = 0x10  # Small buffer
    overflow_data = b'A' * 0x100  # Large data to overflow
    # Craft chunk
    chunk = struct.pack('<H', chunk_id) + struct.pack('<I', fake_length) + overflow_data
    # Write to file
    with open('malicious.3ds', 'wb') as f:
        f.write(header + chunk)

create_malicious_3ds()

Note: This is a simplified example. Real exploitation requires precise knowledge of KeyShot’s heap layout and memory protections (ASLR, DEP).

Blue Team

Detection & Response:

1. Monitor File Activity: Alert on the opening of .3ds files from untrusted sources.
2. Endpoint Detection: Use EDR to monitor for heap corruption or unusual memory access patterns in KeyShot.exe.
3. Network Segmentation: Restrict KeyShot hosts from accessing the internet unless necessary.
4. User Training: Educate users not to open 3DS files from unknown senders.

Indicators of Compromise (IOCs)

• File Hashes (Example):
  • SHA256: e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855 (placeholder)
• Network Indicators:
  • Outbound connections from KeyShot.exe to unknown IPs (if shellcode connects back).
• Process Anomalies:
  • KeyShot.exe spawning child processes (e.g., cmd.exe, powershell.exe).
  • Unusual memory allocations or crashes in KeyShot.exe.
• Registry Changes:
  • Unauthorized modifications to HKEY_LOCAL_MACHINE\SOFTWARE\Luxion\KeyShot.

Detection Engineering

YARA Rule

rule CVE_2024_11576_KeyShot_3DS_Overflow {
    meta:
        description = "Detects malicious 3DS files exploiting CVE-2024-11576"
        author = "Valters IT"
        date = "2025-04-10"
        hash = "unknown"
    strings:
        $chunk_id = { 3D 3D }  // 3D Editor chunk ID
        $overflow_pattern = { 41 41 41 41 }  // 'AAAA' pattern in overflow
    condition:
        $chunk_id at 2 and #overflow_pattern > 10
}

Sigma Rule

title: CVE-2024-11576 KeyShot 3DS File Heap Overflow
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects potential exploitation of CVE-2024-11576 via KeyShot process anomalies
author: Valters IT
date: 2025-04-10
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith: '\KeyShot.exe'
        CommandLine|contains: '.3ds'
    condition: selection
falsepositives:
    - Legitimate use of 3DS files
level: high

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2024-11576 KeyShot 3DS File Heap Overflow - Potential Outbound Connection"; flow:to_server,established; content:"|3D 3D|"; offset:2; depth:2; classtype:attempted-user; sid:1000001; rev:1;)

Remediation & Mitigation

1. No Patch Available: As of now, Luxion has not released a patch. Monitor Luxion’s security advisories for updates.
2. Mitigation:
   • File Handling: Do not open 3DS files from untrusted sources.
   • Application Sandboxing: Run KeyShot in a sandboxed environment (e.g., Windows Sandbox, Firejail).
   • User Training: Educate users on the risks of opening unsolicited files.
   • Endpoint Protection: Deploy EDR solutions to detect anomalous behavior.
3. Workaround: If possible, convert 3DS files to a safer format (e.g., OBJ, FBX) before opening in KeyShot.

Valters IT
Securing Digital Frontiers