URGENT UPDATE GUIDE

QNAP Security Hole: Close the Backdoor in NetBak Replicator & Qsync Central (Update Guide)

By CyberDudeBivash • October 06, 2025 • How-To Guide

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Action Guide: Table of Contents

Chapter 1: The Threat — A Backdoor in Your Backup & Sync Tools

QNAP has released critical security patches for its ecosystem that you must apply immediately. The vulnerabilities create a “backdoor” for hackers in two key applications:

**Qsync Central:** The app on your NAS that syncs files between your devices. A flaw here could let attackers steal your data.
**NetBak Replicator:** The software on your Windows PC that backs up data to your NAS. A flaw here could let attackers take over your entire PC.

Because these are trusted applications that handle your most important data, fixing these security holes is your top priority. For a more technical breakdown, see our **initial threat report**.

Chapter 2: Part 1 — The NAS Fix (Updating Qsync Central)

The first update must be applied directly to your QNAP NAS device.

Log in to your QNAP NAS web interface (the QTS desktop) using your administrator account.
Find and open the **”App Center”** icon on the desktop.
In the App Center, use the search bar at the top to find **”Qsync Central”**.
If a new version is available, the button underneath the app will say **”Update.”** Click this button.
Follow the on-screen prompts to complete the installation. The application will be updated to the secure version automatically.

Chapter 3: Part 2 — The PC Fix (Updating NetBak Replicator)

The second update must be applied to every single Windows computer that uses the NetBak Replicator software.

On your Windows PC, go to the official QNAP support website and find the **”Utilities”** or **”Download Center.”**
Find the **”NetBak Replicator”** software in the list and download the latest version.
Run the installer file you just downloaded. It will automatically upgrade your existing installation to the new, secure version.
**CRITICAL:** You must repeat this process on **every PC** that uses this software to back up data to your NAS.

Chapter 4: The Essential Next Step — Hardening Your QNAP

Patching is essential, but good security is a continuous process. After you have updated your software, take five minutes to perform this critical security check:

Disable Internet Access to Your NAS

Your NAS device should not be directly exposed to the public internet. Log in to your main office or home router (the device from your ISP) and ensure that you are not using **port forwarding** to expose your QNAP’s administration page to the web. Accessing your NAS remotely should always be done through a secure VPN.

Defense in Depth: Your NAS holds your critical data. Protect the devices that access it. A powerful security suite like **Kaspersky Premium** protects your PCs from malware that could be used to attack your NAS from inside your own network.

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About the Author

CyberDudeBivash is a cybersecurity strategist with 15+ years in network and application security, incident response, and threat intelligence, advising organizations across APAC. [Last Updated: October 06, 2025]

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