CVE-2025-61798

Executive Summary

CVE-2025-61798 is a high-severity (CVSS 7.8) out-of-bounds read vulnerability affecting Dassault Systèmes Dimension versions 4.1.4 and earlier. The flaw resides in the parsing of crafted files, where the software reads past the end of an allocated memory structure. This can be weaponized by an attacker to achieve arbitrary code execution in the context of the current user. Exploitation requires user interaction—the victim must open a malicious file. No public exploit code or proof-of-concept is currently available, and no patch has been released by the vendor. The EPSS score is 0.0%, indicating low exploitation likelihood at this time, but the risk remains significant due to the potential for code execution.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It affects a standalone desktop application (Dassault Systèmes Dimension). No supply chain implications are identified.

CVSS Breakdown & Threat Level

• Attack Vector (AV): Local (L) – The attacker must have local access or trick the user into opening a file.
• Attack Complexity (AC): Low (L) – No special conditions required beyond user interaction.
• Privileges Required (PR): None (N) – No authentication needed.
• User Interaction (UI): Required (R) – Victim must open the malicious file.
• Scope (S): Unchanged (U) – The vulnerability does not affect other components.
• Confidentiality (C): High (H) – Potential for full data exposure.
• Integrity (I): High (H) – Code execution can modify system state.
• Availability (A): High (H) – Code execution can lead to denial of service.

Threat Level: High. The vulnerability allows arbitrary code execution with user interaction. While no public exploit exists, the technical details are clear enough for a skilled attacker to develop one.

Deep Dive & Mechanics

The vulnerability is an out-of-bounds read (CWE-125) in the file parsing logic of Dassault Systèmes Dimension. When the application processes a specially crafted file (e.g., a .dwg or proprietary format), it fails to validate the length of a data structure before reading from it. This results in a read past the end of an allocated memory buffer.

Technical Details:

• The parser likely uses a fixed-size buffer or a structure with an assumed length.
• An attacker can craft a file where a length field is larger than the actual allocated memory.
• The out-of-bounds read can leak sensitive memory contents or, if the read is used in a subsequent operation (e.g., as a pointer or size), lead to arbitrary write or code execution.
• Exploitation typically involves heap spraying or ROP chains to redirect execution flow after the read.

Attack Vector:

1. Attacker crafts a malicious file (e.g., via email, download, or USB).
2. Victim opens the file in Dimension.
3. The parser reads beyond the buffer, potentially corrupting adjacent memory.
4. Attacker achieves code execution in the context of the user.

Vulnerable vs. Patched Code

Since no patch is available, a direct comparison is not possible. However, based on the vulnerability type, the fix would involve adding bounds checking before memory reads.

Vulnerable Code (Conceptual):

void parse_file(FILE *file) {
    char buffer[256];
    int length;
    fread(&length, sizeof(int), 1, file);
    // No bounds check
    fread(buffer, 1, length, file); // Out-of-bounds read if length > 256
}

Patched Code (Conceptual):

void parse_file(FILE *file) {
    char buffer[256];
    int length;
    fread(&length, sizeof(int), 1, file);
    if (length > sizeof(buffer)) {
        // Handle error
        return;
    }
    fread(buffer, 1, length, file);
}

Exploitation & Lab Setup

Red Team

Prerequisites:

• Dassault Systèmes Dimension version 4.1.4 or earlier installed on a Windows system.
• A crafted malicious file (e.g., exploit.dwg).

Steps:

1. Craft the Malicious File: Use a fuzzer or manual binary editing to create a file with an oversized length field in a critical structure.
2. Deliver the File: Send via email, file share, or USB.
3. Trigger the Vulnerability: Victim opens the file in Dimension.
4. Achieve Code Execution: The out-of-bounds read can be used to leak addresses or overwrite a function pointer. For example, if the read data is used as a jump target, an attacker can redirect execution to shellcode.

Example Payload (Conceptual):

# Python script to craft a malicious file
import struct

def craft_exploit():
    # Placeholder for actual exploit logic
    payload = b"A" * 256  # Padding
    payload += struct.pack("<I", 0x41414141)  # Overwrite return address
    with open("exploit.dwg", "wb") as f:
        f.write(payload)

craft_exploit()

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

Blue Team

Detection:

• Monitor for unusual file opens of Dimension-related extensions (e.g., .dwg, .dxf).
• Use process monitoring to detect crashes or abnormal memory access patterns.
• Deploy endpoint detection and response (EDR) rules for out-of-bounds read behavior.

Hunting:

• Search for files with anomalous size or structure that trigger crashes in Dimension.
• Analyze crash dumps for signs of heap corruption or controlled memory reads.

Mitigation:

• Restrict execution of Dimension to trusted users only.
• Use application whitelisting to prevent untrusted files from being opened.
• Implement ASLR and DEP to increase exploitation difficulty.

Indicators of Compromise (IOCs)

• File Hashes: (No known samples yet)
• Process Anomalies: Dimension.exe crashing with access violation (0xC0000005) when parsing files.
• Network: No network indicators expected (local file-based).
• Registry: Potential persistence via COM hijacking or scheduled tasks if code execution is achieved.
• YARA Rule: (See Detection Engineering)

Detection Engineering

YARA Rule

rule CVE_2025_61798_Dimension_OOB_Read {
    meta:
        description = "Detects malicious files targeting CVE-2025-61798 in Dassault Systèmes Dimension"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-61798"
    strings:
        $magic = { 41 42 43 44 } // Example magic bytes for crafted file
        $oob_pattern = { FF FF FF FF } // Example oversized length field
    condition:
        $magic at 0 and $oob_pattern
}

Sigma Rule

title: CVE-2025-61798 - Dassault Systèmes Dimension Out-of-Bounds Read
id: 12345678-1234-1234-1234-123456789abc
status: experimental
description: Detects crashes or abnormal behavior in Dimension.exe indicative of CVE-2025-61798 exploitation
author: Valters IT
date: 2025-04-10
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith: '\Dimension.exe'
        CommandLine|contains: '.dwg'
    condition: selection
falsepositives:
    - Legitimate use of Dimension with large files
level: high

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2025-61798 - Potential Malicious File Download"; flow:to_server,established; content:"|41 42 43 44|"; depth:4; classtype:attempted-user; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Isolate: Disable network access for systems running Dimension if possible.
2. Restrict: Use application control policies to block untrusted files.
3. Monitor: Enable enhanced logging for file access and process crashes.

Long-Term Fix:

• Await an official patch from Dassault Systèmes. Until then, consider using alternative software or sandboxing Dimension.
• Implement input validation and bounds checking in custom parsers if source code is available.

Workaround:

• Do not open files from untrusted sources.
• Use a file scanner to detect anomalous structures before opening.

Valters IT
Senior DevSecOps & Cyber Threat Intelligence Expert