CVE-2025-7315

Executive Summary

CVE-2025-7315 is a critical memory corruption vulnerability in the IrfanView CADImage Plugin when parsing specially crafted DWG files. The flaw stems from improper validation of user-supplied data, leading to a memory corruption condition that can be leveraged for remote code execution (RCE) in the context of the current process. User interaction is required—the victim must open a malicious DWG file or visit a malicious page that triggers the plugin. With a CVSS score of 7.8, this vulnerability poses a significant risk to systems using IrfanView with the CADImage Plugin, especially in environments where untrusted DWG files are processed. No public exploit or patch is currently available, but the technical details from ZDI (ZDI-CAN-26408) indicate a high likelihood of weaponization.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It affects a proprietary Windows plugin for IrfanView, a popular image viewer. The CADImage Plugin is distributed separately and may be bundled with other software, creating a supply chain risk if the plugin is included in third-party distributions or enterprise software packages.

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 file)
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: Required
• Scope: Unchanged
• Confidentiality Impact: High
• Integrity Impact: High
• Availability Impact: High

Threat Level: High. Although the EPSS score is 0.0% (indicating low exploitation likelihood currently), the vulnerability is in a widely used plugin and the technical details are known. Once a proof-of-concept is released, exploitation may increase rapidly.

Deep Dive & Mechanics

The vulnerability resides in the CADImage Plugin’s DWG file parser. DWG files are binary formats used by AutoCAD and other CAD software. The plugin attempts to parse these files to display previews or thumbnails. The specific flaw is a memory corruption caused by insufficient validation of data within the DWG file structure.

Root Cause: The parser does not properly check the size or boundaries of user-supplied data when reading certain fields (e.g., block definitions, layer names, or entity data). This can lead to a buffer overflow or write-what-where condition, allowing an attacker to overwrite critical memory structures.

Attack Vector: An attacker crafts a malicious DWG file with oversized or malformed fields. When the victim opens this file in IrfanView (or a browser that uses the plugin), the parser processes the malicious data, corrupting memory. This can be leveraged to hijack the execution flow and execute arbitrary shellcode.

Impact: Successful exploitation grants the attacker code execution with the privileges of the current user. This can lead to data theft, installation of malware, or lateral movement within a network.

Vulnerable vs. Patched Code

Since no patch is available, a direct code comparison is not possible. However, based on the vulnerability description, the patched code would include:

• Vulnerable: The parser reads a length field from the DWG file and uses it to copy data into a fixed-size buffer without validation.

  // Vulnerable pseudo-code
  char buffer[256];
  int length = read_int_from_dwg();
  read_data_from_dwg(buffer, length); // No bounds check
  

• Patched: The parser would validate the length against the buffer size before copying.

  // Patched pseudo-code
  char buffer[256];
  int length = read_int_from_dwg();
  if (length > sizeof(buffer)) {
      // Handle error
      return;
  }
  read_data_from_dwg(buffer, length);
  

Exploitation & Lab Setup

Red Team (Offensive)

Prerequisites:

• IrfanView with CADImage Plugin installed (any version).
• A Windows machine for testing.

Steps:

1. Craft Malicious DWG: Use a fuzzer or manual binary editing to create a DWG file with an oversized field (e.g., a block name of 500 bytes).
2. Deliver Payload: Embed shellcode (e.g., a reverse shell) in the DWG file. The memory corruption should overwrite a function pointer or return address.
3. Trigger: Send the file to the victim via email or a download link. The victim must open it with IrfanView.
4. Exploit: Upon opening, the parser triggers the memory corruption, executing the shellcode.

Example Exploit Skeleton (Python):

import struct

def create_malicious_dwg():
    # Simplified DWG structure
    header = b'\x41\x43\x31\x30'  # AC1015
    # Malicious block name (overly long)
    block_name = b'A' * 500
    # Shellcode placeholder
    shellcode = b'\x90' * 100 + b'\xcc'  # NOP sled + INT3
    payload = header + struct.pack('<I', len(block_name)) + block_name + shellcode
    with open('malicious.dwg', 'wb') as f:
        f.write(payload)

create_malicious_dwg()

Blue Team (Defensive)

Detection:

• Monitor for unusual DWG files with abnormally large fields.
• Use endpoint detection rules to flag IrfanView processes that crash or exhibit abnormal memory access.

Prevention:

• Disable the CADImage Plugin if not needed.
• Use application whitelisting to prevent IrfanView from executing untrusted plugins.
• Sandbox IrfanView in a restricted environment.

Hunting:

• Search for DWG files with header anomalies or oversized sections.
• Analyze crash dumps from IrfanView for signs of exploitation.

Indicators of Compromise (IOCs)

• File Hashes: (Example – replace with actual when available)
  • malicious.dwg: SHA256 e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855
• Network: Outbound connections from IrfanView process to unknown IPs (if shellcode initiates a reverse shell).
• Process: IrfanView.exe crashing with memory access violations.
• Registry: Unusual plugin registrations or modifications to IrfanView settings.
• File System: Presence of DWG files with non-standard sizes or structures in temporary directories.

Detection Engineering

YARA Rule

rule CVE_2025_7315_DWG_Memory_Corruption {
    meta:
        description = "Detects malicious DWG files targeting IrfanView CADImage Plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-7315"
    strings:
        $dwg_header = { 41 43 31 [0-1] 30 [0-1] }  // AC10xx variants
        $long_block = /[\x00-\xFF]{300,}/  // Block name > 300 bytes
    condition:
        $dwg_header at 0 and #long_block > 0
}

Sigma Rule

title: CVE-2025-7315 IrfanView CADImage Plugin Exploitation
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects potential exploitation of CVE-2025-7315 via crash or abnormal behavior
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith: '\IrfanView.exe'
        CommandLine|contains: '.dwg'
    condition: selection
falsepositives:
    - Legitimate DWG file opening
level: high

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2025-7315 IrfanView CADImage Plugin Exploit"; flow:to_server,established; content:"|41 43 31|"; depth:3; content:"|00|"; within:100; byte_test:4,>,300,0,relative; classtype:attempted-user; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate: Disable or uninstall the CADImage Plugin from IrfanView until a patch is released.
2. Workaround: Do not open DWG files from untrusted sources. Use alternative viewers that are actively maintained.
3. Monitoring: Implement the YARA and Sigma rules above to detect malicious DWG files.
4. Patch: Monitor the IrfanView website or ZDI for an official patch. Apply as soon as available.
5. User Training: Educate users on the risks of opening unsolicited attachments, especially DWG files.

Valters IT
Securing Digital Frontiers