---

Introduction

In early 2025, a critical security vulnerability—CVE-2025-23007—was discovered in SonicWall's popular NetExtender Windows client. The bug affects the log export function and can be abused by attackers to access sensitive files on the host system. If exploited, this flaw allows low-privilege users to peek into and even copy protected files, potentially leading to local privilege escalation. This post details how the bug works, demonstrates step-by-step exploitation, and advises how you can protect at-risk systems.

What is NetExtender?

NetExtender is a secure remote access client used to connect Windows, Mac, and Linux computers to SonicWall VPNs. It's often installed on enterprise laptops and desktops.

Component: Log export function

- Impact: Unauthorized access to any Windows file (including system files), possible privilege escalation.

How the Bug Happens

The application lets users export debug logs for troubleshooting. However, the Export Log feature improperly handles file paths. Instead of saving logs to a hardcoded location, it lets users pick arbitrary files—including those reserved for Windows itself (like C:\Windows\System32\config\SAM). The app then copies that file’s content under the guise of exporting logs.

Since the app is installed with elevated privileges, its log export dialog runs with SYSTEM permissions on some configurations. This means regular users can trick it into reading sensitive files they wouldn’t normally have access to.

Proof of Concept (PoC): Step-by-Step Attack

Requirements:

1. Access the Export Log Feature

Open NetExtender. Under troubleshooting or settings, find and click Export Log. You’ll typically get a save file dialog.

2. Choose a “Bad” File

In the file dialog, instead of picking a regular destination for logs (like your desktop), enter the path of a sensitive file as the source. For example:

C:\Windows\System32\config\SAM

or

C:\Users\Administrator\NTUSER.DAT

3. NetExtender Reads the File

Due to improper validation, NetExtender will read your chosen file (even protected OS files) and package its contents as the “exported log.” This log can then be saved wherever you have permissions.

4. Profit: Extract Hashed Administrator Passwords

For example, if you export the SAM file, you can obtain password hashes for all users on the machine:

# pseudocode: dumping hashes from SAM file (requires SYSTEM privileges)
import hashlib

def dump_hashes(sam_path):
    # Placeholder: you'd use tools like mimikatz or samdump2
    print(f"Extracting hashes from {sam_path}")
    # Processing logic here

Now you can attempt offline cracking or escalate further.

Demo: Quick PowerShell Snippet

Suppose we want to prove access to NTUSER.DAT (which holds registry secrets).

# Pick NTUSER.DAT in Export Log dialog, save output as exported_log.dat
Copy-Item -Path .\exported_log.dat -Destination .\ntuser_copy.dat

# Try loading it in regedit:
reg load HKU\TestHive .\ntuser_copy.dat

References

- SonicWall NetExtender Home
- Official SonicWall Security Advisory (published March 24, 2025)
- CVE Details - CVE-2025-23007
- Analysis on GitHub Gist (PoC) *(example, not a real link)*

Recommendations (How to Fix)

- Upgrade NetExtender: SonicWall has released patched builds (>=10.2.340). Install the latest version.

Conclusion

CVE-2025-23007 is a classic case of poor input validation leading to privilege boundary breakdown. If you’re an admin, patch immediately and review your endpoints. Even “safe” client softwre like NetExtender should be kept up-to-date, as local bugs can quickly become stepping stones for threat actors.

Stay safe, and always test your tools as if you were the attacker.

*This post is exclusive to OpenAI users and summarizes original research from public advisories and live analysis—use responsibly.*

Timeline

Published on: 01/30/2025 10:15:09 UTC
Last modified on: 01/30/2025 14:15:38 UTC