CVE-2023-34294

Executive Summary

CVE-2023-34294 is a Use-After-Free (UAF) vulnerability in Sante DICOM Viewer Pro, specifically during the parsing of DCM files. The flaw allows a remote attacker to disclose sensitive information by tricking a user into opening a malicious DCM file or visiting a malicious page. The vulnerability arises from improper validation of object existence before performing operations, leading to a use-after-free condition. While the CVSS score is low (3.3), the issue can be chained with other vulnerabilities to achieve arbitrary code execution in the context of the current process. No public exploit code or patch is currently available.

Supply Chain & Package Security

This vulnerability is not related to any package manager (NPM, PyPI, Go, Ruby). It affects a standalone desktop application (Sante DICOM Viewer Pro) distributed via the vendor’s website or third-party repositories. Users should verify the integrity of downloaded binaries and consider sandboxing the application.

CVSS Breakdown & Threat Level

• CVSS Score: 3.3 (Low)
• Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N
• Attack Vector: Local (requires user interaction)
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: Required
• Scope: Unchanged
• Confidentiality Impact: Low
• Integrity Impact: None
• Availability Impact: None

Threat Level: Low (due to high user interaction requirement and limited direct impact). However, chaining with other vulnerabilities could elevate severity.

Deep Dive & Mechanics

The vulnerability exists in the DCM file parsing module of Sante DICOM Viewer Pro. When processing a specially crafted DCM file, the application fails to properly validate that an object is still valid before performing operations on it. This results in a use-after-free condition, where memory that has been freed is accessed again.

Technical Details:

• Root Cause: Lack of validation of object existence prior to use.
• Trigger: Opening a malicious DCM file or visiting a malicious page that loads the file.
• Impact: Information disclosure (memory leak) that could reveal sensitive data or be used to bypass ASLR.
• Chaining Potential: The leaked memory can be used to craft further exploits, potentially leading to arbitrary code execution.

Affected Component: DCM file parser (specific function unknown).

Vulnerable vs. Patched Code

No patch is available. The vulnerable code likely resembles:

// Vulnerable pseudo-code
void parse_dcm_object(DCMObject *obj) {
    // No check if obj is still valid
    process_object(obj); // Use after free if obj was freed
}

A patched version would include a validation check:

// Patched pseudo-code
void parse_dcm_object(DCMObject *obj) {
    if (obj == NULL || is_freed(obj)) {
        return; // Safe handling
    }
    process_object(obj);
}

Exploitation & Lab Setup

Red Team

Prerequisites:

• Sante DICOM Viewer Pro (any version)
• A crafted DCM file

Steps:

1. Create a malicious DCM file that triggers the use-after-free condition.
2. Host the file on a web server or send via email.
3. Convince the target user to open the file in Sante DICOM Viewer Pro.
4. The vulnerability will leak memory contents, which can be captured via a debugger or side-channel.

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

# Conceptual exploit (not functional)
import struct

def craft_malicious_dcm():
    # Craft a DCM file that triggers UAF
    # This is a placeholder for actual exploit logic
    payload = b"\x00" * 1000  # Placeholder
    with open("malicious.dcm", "wb") as f:
        f.write(payload)

craft_malicious_dcm()

Blue Team

Detection:

• Monitor for unusual DCM file downloads or email attachments.
• Use process monitoring to detect crashes or abnormal memory access in Sante DICOM Viewer Pro.
• Enable Application Verifier or similar tools to catch use-after-free conditions.

Mitigation:

• Restrict execution of Sante DICOM Viewer Pro in sandboxed environments.
• Educate users not to open DCM files from untrusted sources.
• Apply strict file access controls.

Indicators of Compromise (IOCs)

• File Hashes (MD5): Unknown (no public samples)
• Network Indicators: None specific
• Behavioral:
  • Sante DICOM Viewer Pro crash logs
  • Abnormal memory access patterns
  • Unexpected DICOM file downloads

Detection Engineering

YARA Rule

rule CVE_2023_34294_Sante_DICOM_UAF {
    meta:
        description = "Detects malicious DCM files targeting CVE-2023-34294"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2023-34294"
    strings:
        $s1 = "DICOM" ascii wide nocase
        $s2 = { 08 00 01 00 } // Example DICOM tag
    condition:
        $s1 and $s2 and filesize < 10MB
}

Sigma Rule

title: Sante DICOM Viewer Pro Use-After-Free Exploitation Attempt
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects potential exploitation of CVE-2023-34294 via malicious DCM file
author: Valters IT
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith: 'DicomViewerPro.exe'
        CommandLine|contains: '.dcm'
    condition: selection
falsepositives:
    - Legitimate DICOM file viewing
level: medium

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2023-34294 Sante DICOM Viewer Pro UAF Attempt"; flow:to_server,established; content:"DICM"; offset:128; depth:4; classtype:attempted-user; sid:1000001; rev:1;)

Remediation & Mitigation

• No official patch available. Contact vendor for updates.
• Mitigation:
  • Do not open DCM files from untrusted sources.
  • Use application sandboxing (e.g., Windows Sandbox, Firejail).
  • Monitor for abnormal application behavior.
  • Consider using alternative DICOM viewers with active security support.

Valters IT
Senior DevSecOps & Cyber Threat Intelligence Expert