CVE-2025-7309

Executive Summary

CVE-2025-7309 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. The CVSS score is 7.8 (High), and no public exploit or patch is currently available. This vulnerability poses a significant risk to users of IrfanView with the CADImage Plugin installed, particularly in environments where untrusted DWG files are processed.

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
• Scope: Unchanged
• Confidentiality Impact: High
• Integrity Impact: High
• Availability Impact: High

The threat level is high due to the potential for full system compromise with minimal user interaction.

Deep Dive & Mechanics

The vulnerability exists in the CADImage Plugin’s handling of DWG file format structures. DWG files contain binary data representing 2D and 3D CAD drawings. The plugin fails to properly validate the size or boundaries of data read from the file, leading to a buffer overflow or other memory corruption. An attacker can craft a DWG file with oversized or malformed fields that overwrite adjacent memory regions, potentially hijacking the execution flow.

The specific flaw is in the parsing routine for DWG file sections (e.g., header, entity data). When the plugin reads a length field that is larger than the allocated buffer, it copies data beyond the buffer’s bounds, corrupting heap or stack memory. This can be exploited to execute arbitrary shellcode.

Vulnerable vs. Patched Code

Since no patch is available, the vulnerable code is the current implementation in the CADImage Plugin. A patched version would include bounds checking and input validation.

Vulnerable code snippet (conceptual):

void parse_dwg_section(char *buffer, int length) {
    char section_data[256];
    memcpy(section_data, buffer, length); // No bounds check
    // Process section_data...
}

Patched code snippet (conceptual):

void parse_dwg_section(char *buffer, int length) {
    char section_data[256];
    if (length > sizeof(section_data)) {
        // Handle error or truncate
        return;
    }
    memcpy(section_data, buffer, length);
    // Process section_data...
}

Exploitation & Lab Setup

Red Team

Lab Setup:

• Target: Windows 10/11 with IrfanView 4.66 and CADImage Plugin installed.
• Attacker: Kali Linux with Metasploit or custom exploit script.

Exploitation Steps:

1. Craft a malicious DWG file using a fuzzer or manual binary editing to trigger the overflow.
2. Host the file on a web server or send via email.
3. Victim opens the file in IrfanView, triggering the vulnerability.
4. The exploit overwrites a function pointer or return address to redirect execution to shellcode.
5. Shellcode executes, providing a reverse shell or other payload.

Example exploit skeleton (Python):

import struct

# Craft DWG header with oversized length field
payload = b"A" * 256  # Padding
payload += struct.pack("<I", 0xdeadbeef)  # Overwritten return address
# Append shellcode
payload += b"\x90" * 16 + shellcode

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

Blue Team

Detection:

• Monitor for IrfanView crashes or abnormal memory access.
• Use process monitoring tools (e.g., Sysmon) to detect child processes spawned by IrfanView.
• Enable Windows Defender Exploit Guard to mitigate memory corruption.

Hunting:

• Search for DWG files with unusually large sizes or malformed headers.
• Analyze crash dumps for signs of heap spray or ROP chains.

Indicators of Compromise (IOCs)

• File Hashes: (Example, not real) malicious.dwg SHA256: a1b2c3d4e5f6...
• Network: Outbound connections from IrfanView process to unknown IPs.
• Process: IrfanView.exe spawning cmd.exe or powershell.exe.
• Registry: Unusual entries in HKCU\Software\IrfanView.
• Memory: Heap corruption patterns in crash dumps.

Detection Engineering

YARA Rule

rule CVE_2025_7309_DWG_Memory_Corruption {
    meta:
        description = "Detects malicious DWG files exploiting CVE-2025-7309"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2025-7309"
    strings:
        $dwg_header = "AC10" // DWG version header
        $overflow_pattern = { 41 41 41 41 41 41 41 41 } // 'AAAAAAAA' padding
    condition:
        $dwg_header at 0 and #overflow_pattern > 5
}

Sigma Rule

title: CVE-2025-7309 IrfanView CADImage Plugin Exploitation
id: 8f9e2c1a-3b4d-5e6f-7a8b-9c0d1e2f3a4b
status: experimental
description: Detects potential exploitation of CVE-2025-7309 via process anomalies
author: Valters IT
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        ParentImage|endswith: '\IrfanView.exe'
        Image|endswith:
            - '\cmd.exe'
            - '\powershell.exe'
            - '\wscript.exe'
    condition: selection
falsepositives:
    - Legitimate use of command line tools by user
level: high

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2025-7309 IrfanView CADImage Plugin RCE"; flow:to_server,established; content:"|41 41 41 41|"; depth:100; classtype:attempted-user; sid:1000001; rev:1;)

Remediation & Mitigation

• Immediate: Disable the CADImage Plugin or uninstall it until a patch is available.
• User Awareness: Train users not to open DWG files from untrusted sources.
• Network: Block DWG file downloads at the perimeter if possible.
• System Hardening: Enable ASLR, DEP, and EMET/Exploit Guard.
• Monitoring: Deploy the above detection rules and monitor for suspicious activity.
• Vendor Contact: Monitor IrfanView’s website for updates or contact support.

Valters IT
Securing Digital Frontiers