CVE-2025-7318

Executive Summary

CVE-2025-7318 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. The vulnerability has a CVSS score of 7.8 (High) and is currently unpatched. No public proof-of-concept (PoC) or exploit code has been released, and the EPSS score is 0.0%, indicating low exploitation activity in the wild. However, given the severity and the lack of a patch, organizations using IrfanView with the CADImage Plugin should treat this as a high-priority risk.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby ecosystems. It affects a standalone Windows desktop application (IrfanView) and its third-party plugin (CADImage Plugin). The risk is primarily to end-user workstations where IrfanView is installed for viewing CAD files.

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 required.
• Privileges Required (PR): None (N) – No authentication needed.
• User Interaction (UI): Required (R) – Victim must open the file.
• Scope (S): Unchanged (U) – Exploitation stays within the vulnerable component.
• Confidentiality (C): High (H) – Full data access possible.
• Integrity (I): High (H) – Arbitrary code execution.
• Availability (A): High (H) – Potential for denial of service or system compromise.

Threat Level: High. Although no active exploitation has been observed, the vulnerability is easily exploitable with user interaction and can lead to full system compromise.

Deep Dive & Mechanics

The vulnerability resides in the CADImage Plugin (CADImage.dll) used by IrfanView to parse DWG files. DWG is a binary file format used by AutoCAD. The plugin fails to properly validate the size or structure of certain data fields within the DWG file, leading to a memory corruption (likely a buffer overflow or use-after-free) when parsing.

Technical Details:

• Root Cause: Lack of bounds checking on user-supplied data during DWG parsing.
• Trigger: Opening a malicious DWG file (or visiting a page that loads it via the plugin).
• Impact: Memory corruption allows an attacker to overwrite critical data structures (e.g., function pointers, return addresses) and achieve arbitrary code execution.
• Process Context: The exploit runs in the context of the IrfanView process, which typically has the same privileges as the logged-in user.

Attack Flow:

1. Attacker crafts a malicious DWG file with specially crafted data fields.
2. Attacker delivers the file via email, download, or malicious website.
3. Victim opens the file with IrfanView (or a browser that uses the plugin).
4. The plugin parses the DWG, triggering the memory corruption.
5. Attacker-controlled code executes, potentially installing malware, exfiltrating data, or taking over the system.

Vulnerable vs. Patched Code

Since no patch is available, a direct code comparison is not possible. However, based on the vulnerability description, the vulnerable code likely resembles:

// Vulnerable pseudo-code
void ParseDWGData(char *buffer, int size) {
    char local_buffer[256];
    // No bounds check on size
    memcpy(local_buffer, buffer, size); // Potential overflow
}

A patched version would include proper validation:

// Patched pseudo-code
void ParseDWGData(char *buffer, int size) {
    char local_buffer[256];
    if (size > sizeof(local_buffer)) {
        // Handle error
        return;
    }
    memcpy(local_buffer, buffer, size);
}

Exploitation & Lab Setup

Red Team (Offensive)

Prerequisites:

• IrfanView with CADImage Plugin installed.
• A Windows VM for testing.
• A debugger (e.g., x64dbg) and a fuzzer (e.g., boofuzz) for crafting the malicious DWG.

Steps:

1. Fuzzing: Use a DWG fuzzer to identify crash-inducing inputs.
2. Crash Analysis: Attach a debugger to IrfanView and open the crashing DWG to identify the overwritten offset.
3. Exploit Development: Craft a DWG file that overwrites a return address or SEH handler with a controlled value.
4. Shellcode: Use a standard Windows shellcode (e.g., reverse shell) and ensure it is position-independent.
5. Delivery: Host the malicious DWG on a website or send via email.

Example (Conceptual):

# Python script to generate a malicious DWG (simplified)
import struct

# Craft a DWG header and payload
payload = b"A" * 256  # Padding
payload += struct.pack("<I", 0x90909090)  # NOP sled
payload += shellcode  # Actual shellcode

with open("malicious.dwg", "wb") as f:
    f.write(payload)

Blue Team (Defensive)

Detection:

• Monitor for IrfanView crashes (Event ID 1000 in Windows Application logs).
• Use file reputation services to block known malicious DWG files.
• Deploy endpoint detection and response (EDR) to detect memory corruption anomalies.

Prevention:

• Disable the CADImage Plugin if not needed.
• Use application whitelisting to prevent IrfanView from executing untrusted code.
• Implement user awareness training to avoid opening suspicious DWG files.

Indicators of Compromise (IOCs)

• File Hashes: (None publicly available; generate upon discovery)
• Network Indicators: Outbound connections from IrfanView process to unknown IPs.
• Process Behavior: IrfanView.exe spawning child processes (e.g., cmd.exe, powershell.exe).
• Registry Changes: Unusual modifications to HKCU\Software\IrfanView.
• File System: Creation of new executable files in %TEMP% or %APPDATA%.

Detection Engineering

YARA Rule

rule CVE_2025_7318_DWG_Malicious {
    meta:
        description = "Detects malicious DWG files targeting CVE-2025-7318"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2025-7318"
    strings:
        $dwg_header = { 41 43 31 30 } // "AC10" (DWG header)
        $suspicious_payload = /[A-Za-z0-9\/+]{100,}/ // Base64-like long strings
    condition:
        $dwg_header at 0 and #suspicious_payload > 3
}

Sigma Rule

title: CVE-2025-7318 IrfanView CADImage Plugin Memory Corruption
id: 8a9b3c4d-5e6f-7a8b-9c0d-1e2f3a4b5c6d
status: experimental
description: Detects potential exploitation of CVE-2025-7318 via IrfanView crashes
author: Valters IT
date: 2025-04-10
logsource:
    product: windows
    service: application
detection:
    selection:
        EventID: 1000
        ApplicationName: 'IrfanView.exe'
        FaultModuleName: 'CADImage.dll'
    condition: selection
falsepositives:
    - Legitimate crashes due to corrupted files
level: high

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET $HTTP_PORTS (msg:"CVE-2025-7318 Potential DWG Malware Download"; flow:to_server,established; content:"|41 43 31 30|"; distance:0; within:4; fileext:"dwg"; classtype:attempted-user; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the CADImage Plugin: Remove or rename CADImage.dll in the IrfanView plugins folder.
2. User Education: Warn users not to open DWG files from untrusted sources.
3. Network Filtering: Block DWG file downloads at the perimeter if not business-required.

Long-Term:

• Monitor the vendor for a patch and apply it immediately when released.
• Consider using alternative CAD viewers that are actively maintained.
• Implement application control to restrict IrfanView execution.

Workaround: If the plugin is essential, use a sandbox or virtual machine to open DWG files.

Valters IT
Senior DevSecOps & Cyber Threat Intelligence Expert