CVE-2025-7317

Executive Summary

CVE-2025-7317 is a critical memory corruption vulnerability in the IrfanView CADImage Plugin when parsing specially crafted DWG files. The flaw allows remote code execution (RCE) in the context of the current user process, requiring only that the victim opens a malicious DWG file or visits a malicious page that triggers the plugin. With a CVSS score of 7.8, the vulnerability is considered high severity due to the potential for full system compromise. No public proof-of-concept (PoC) or exploit code has been released, and the vendor has not confirmed a patch. The EPSS score is 0.0%, indicating low exploitation likelihood at this time, but the risk remains significant for users of the plugin.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby ecosystems. It affects a standalone Windows plugin for IrfanView, a popular image viewer. The plugin is distributed via the official IrfanView website and third-party download sites. Users should verify the integrity of downloaded plugin files and consider using alternative DWG viewers until a patch is available.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
• Base Score: 7.8 (High)
• 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

Threat Level: High – Exploitation could lead to full system compromise, but user interaction is required.

Deep Dive & Mechanics

The vulnerability resides in the CADImage Plugin’s parsing of DWG files. DWG is a binary format used by AutoCAD and other CAD applications. The plugin fails to properly validate user-supplied data during parsing, leading to a memory corruption condition (likely a buffer overflow or use-after-free). An attacker can craft a malicious DWG file that, when opened in IrfanView, triggers the corruption and allows arbitrary code execution.

Root Cause: Lack of bounds checking or input validation when processing DWG file structures (e.g., section headers, entity records, or coordinate data). The plugin may copy data into fixed-size buffers without verifying length, or may use pointers that become invalid after certain operations.

Attack Vector: The attacker delivers the malicious DWG file via email, web download, or other means. The victim must open the file with IrfanView (or a browser that uses the plugin). No additional privileges are required.

Impact: Successful exploitation grants the attacker code execution in the context of the IrfanView process, which typically runs with the user’s privileges. This can lead to data theft, malware installation, or lateral movement.

Vulnerable vs. Patched Code

Since no patch is available, a direct code comparison is not possible. However, based on the vulnerability type (memory corruption), the following general differences are expected:

Vulnerable Code (Hypothetical):

void parse_dwg_section(char *data, int len) {
    char buffer[256];
    memcpy(buffer, data, len); // No length check
}

Patched Code (Hypothetical):

void parse_dwg_section(char *data, int len) {
    char buffer[256];
    if (len > sizeof(buffer)) {
        // Handle error
        return;
    }
    memcpy(buffer, data, len);
}

The patch would add input validation, bounds checking, and safe memory handling (e.g., using strncpy or memcpy_s).

Exploitation & Lab Setup

Red Team (Offensive)

Prerequisites:

• IrfanView with CADImage Plugin installed (any version)
• A malicious DWG file crafted to trigger the vulnerability

Steps:

1. Craft the Malicious DWG: Use a fuzzer or manual binary editing to create a DWG file with oversized or malformed data in a section that triggers the memory corruption. For example, modify the header length field to a large value.
2. Deliver the File: Send the file via email or host it on a website.
3. Trigger Exploitation: The victim opens the file in IrfanView. The plugin parses the file, causing a buffer overflow that overwrites a function pointer or return address.
4. Execute Payload: The attacker’s shellcode (e.g., a reverse shell) is executed.

Example (Conceptual):

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

def create_malicious_dwg():
    # DWG header (simplified)
    header = b'\x41\x43\x31\x30'  # Magic bytes
    # Malicious section with oversized data
    payload = b'A' * 1000  # Trigger overflow
    with open('malicious.dwg', 'wb') as f:
        f.write(header + payload)

create_malicious_dwg()

Note: No public exploit code is available. This is a conceptual example.

Blue Team (Defensive)

Detection:

• Monitor for IrfanView crashes or unusual process behavior.
• Use file reputation services to block known malicious DWG files.
• Deploy endpoint detection and response (EDR) rules for memory corruption events.

Prevention:

• Disable the CADImage Plugin if not needed.
• Use application whitelisting to prevent IrfanView from executing untrusted code.
• Keep software updated (though no patch exists, monitor for updates).

Hunting:

• Search for DWG files with unusual sizes or structures.
• Analyze crash dumps for signs of exploitation (e.g., stack corruption).

Indicators of Compromise (IOCs)

• File Hashes: (No known samples; placeholder)
  • malicious.dwg SHA256: e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855
• Network: Outbound connections from IrfanView process (e.g., to attacker C2)
• Process: IrfanView.exe spawning child processes (e.g., cmd.exe, powershell.exe)
• Registry: Unusual modifications to HKCU\Software\IrfanView
• Memory: Signs of heap spray or ROP chains in IrfanView process memory

Detection Engineering

YARA Rule

rule CVE_2025_7317_DWG_Malicious {
    meta:
        description = "Detects malicious DWG files targeting CVE-2025-7317"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2025-7317"
    strings:
        $magic = { 41 43 31 30 }  // DWG magic bytes
        $overflow = { 41 41 41 41 }  // Pattern of 'A's (example)
    condition:
        $magic at 0 and #overflow > 100
}

Sigma Rule

title: IrfanView CADImage Plugin Memory Corruption
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects potential exploitation of CVE-2025-7317 via crash or abnormal process behavior
author: Valters IT
date: 2025-04-10
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith: '\IrfanView.exe'
        CommandLine|contains: '.dwg'
    condition: selection
falsepositives:
    - Legitimate DWG file viewing
level: high

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2025-7317 IrfanView DWG Exploit Outbound"; flow:to_server; content:"|41 43 31 30|"; depth:4; classtype:attempted-user; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the CADImage Plugin: Remove or rename the plugin DLL (e.g., CADImage.dll) in the IrfanView plugins folder.
2. Use Alternative Software: Switch to a different DWG viewer (e.g., Autodesk DWG TrueView, LibreCAD).
3. User Awareness: Train users not to open DWG files from untrusted sources.

Long-Term:

• Monitor the vendor’s website for a patch.
• Implement application control policies to block IrfanView from executing untrusted code.
• Deploy memory protection mechanisms (e.g., ASLR, DEP, CFG).

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

Valters IT
Senior DevSecOps & Cyber Threat Intelligence Expert