CVE-2025-7322

Executive Summary

CVE-2025-7322 is a critical out-of-bounds read vulnerability in the IrfanView CADImage Plugin when parsing specially crafted DWG files. The flaw allows remote code execution in the context of the current process, requiring user interaction (opening a malicious file or visiting a malicious page). With a CVSS score of 7.8, this vulnerability poses a significant risk to systems using IrfanView with the CADImage Plugin. No public exploit code or patch is currently available, but the vulnerability is weaponizable via crafted DWG files.

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 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 resides in the CADImage Plugin’s DWG file parser. The plugin fails to validate user-supplied data when reading DWG file structures, leading to a read past the end of an allocated buffer. This out-of-bounds read can be leveraged by an attacker to execute arbitrary code in the context of the IrfanView process. The flaw is triggered when a user opens a malicious DWG file or visits a page that loads such a file.

The root cause is a missing bounds check on an index or pointer used during parsing, allowing an attacker to control the read offset and potentially corrupt memory or execute shellcode.

Vulnerable vs. Patched Code

Since no patch is available, a hypothetical vulnerable code snippet is provided:

Vulnerable Code (C-style pseudocode):

void parse_dwg_header(char *buffer, size_t size) {
    uint32_t offset = *(uint32_t*)(buffer + 0x10); // Attacker-controlled offset
    char *data = buffer + offset; // No bounds check
    process_data(data);
}

Patched Code (Hypothetical):

void parse_dwg_header(char *buffer, size_t size) {
    uint32_t offset = *(uint32_t*)(buffer + 0x10);
    if (offset >= size) {
        return; // Bounds check added
    }
    char *data = buffer + offset;
    process_data(data);
}

Exploitation & Lab Setup

Red Team

Exploitation Steps:

1. Craft a malicious DWG file with a manipulated offset field in the header.
2. Host the file on a web server or deliver via email.
3. Convince the target to open the file with IrfanView CADImage Plugin.
4. The out-of-bounds read triggers code execution.

Proof-of-Concept (No public exploit available):

# Hypothetical PoC - Not functional
import struct

def craft_malicious_dwg():
    header = b'\x41\x41\x41\x41'  # Placeholder
    offset = struct.pack('<I', 0xFFFFFFFF)  # Out-of-bounds offset
    payload = b'\x90' * 1000  # NOP sled
    return header + offset + payload

with open('malicious.dwg', 'wb') as f:
    f.write(craft_malicious_dwg())

Blue Team

Detection & Mitigation:

• Monitor for IrfanView crashes or unusual memory access patterns.
• Use application whitelisting to block IrfanView from executing untrusted files.
• Deploy endpoint detection and response (EDR) rules for out-of-bounds read behavior.

Lab Setup:

• Install IrfanView with CADImage Plugin on a Windows VM.
• Use a debugger (e.g., WinDbg) to analyze crash dumps.
• Test with crafted DWG files in an isolated environment.

Indicators of Compromise (IOCs)

• File Hashes (SHA256): None available (no known samples).
• Network Indicators: None (local file exploitation).
• Behavioral: IrfanView process crash or abnormal memory access.
• Registry: No known persistence mechanisms.

Detection Engineering

YARA Rule

rule CVE_2025_7322_DWG_OOB_Read {
    meta:
        description = "Detects malicious DWG files exploiting CVE-2025-7322"
        author = "Valters IT"
        date = "2025-04-01"
    strings:
        $dwg_magic = { 41 43 31 30 } // DWG magic bytes (example)
        $suspicious_offset = { FF FF FF FF } // Potential out-of-bounds offset
    condition:
        $dwg_magic at 0 and $suspicious_offset
}

Sigma Rule

title: IrfanView CADImage Plugin DWG Out-of-Bounds Read
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects potential exploitation of CVE-2025-7322 via process crash or memory access violation
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith: 'i_view32.exe'
        CommandLine|contains: '.dwg'
    condition: selection
falsepositives:
    - Legitimate DWG file parsing
level: high

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2025-7322 IrfanView DWG Out-of-Bounds Read"; flow:to_server,established; content:"|41 43 31 30|"; offset:0; depth:4; content:"|FF FF FF FF|"; within:100; classtype:attempted-user; sid:1000001; rev:1;)

Remediation & Mitigation

• Immediate: Disable the CADImage Plugin or restrict its use to trusted files only.
• Workaround: Use alternative DWG viewers until a patch is released.
• Long-term: Monitor vendor channels for an official patch. Implement strict file validation and sandboxing for IrfanView.
• User Training: Educate users not to open untrusted DWG files or visit suspicious pages.

Valters IT
Securing Digital Frontiers