You really shouldn’t use a custom Windows ISO – XDA Developers

You really shouldn’t use a custom Windows ISO – XDA Developers

Key takeaways

  • Custom Windows ISOs can be risky due to potential modifications that could compromise your system security.
  • Consider using post-installation scripts to modify your operating system without the risks associated with custom ISOs.
  • If you want a custom Windows image, creating one yourself is safer than trusting closed third-party distributions.

Custom Windows ISOs have attracted a lot of attention online recently, with many singing the praises of these tweaked and customized distros for everything from improving privacy, reducing telemetry, and improving performance overall and in Games. But make no mistake, Windows ISOs are not the same as their Linux distribution cousins ​​and can pose a serious security threat.

Fortunately, there are some great alternative tools that can help you get the same fast, bloat-free operating system without the risks.

What are custom ISOs?

Custom ISOs are modified and repackaged versions of Windows

Custom images for Windows have been around almost as long as Windows, and indeed for any other software packaged as images. There’s a whole ecosystem of tools that lets you download an image distributed by Microsoft for Windows: .iso files that you download and burn to a USB stick or CD. Before you install these images, you can open and modify them, adding features, installing software, or making changes to Windows for various reasons.

Many users online edit and create these custom images for various purposes and then offer them for download. This can range from removing bloatware to improving gaming performance or disabling tracking cookies, but there are more nefarious reasons as well.

Why are custom ISOs dangerous?

It is unclear what could have been changed in an ISO


Source: TechLatest

Custom Windows ISOs are basically extremely dangerous and you should not use them. This is largely because there is no easy way to tell which elements of an ISO have been changed (without inspecting it yourself against a valid ISO – a difficult process). This means that once installed, your PC could immediately become part of a botnet, have a malicious rootkit installed, or any other dangerous program.

You also sacrifice any other protections you have by providing a potentially malicious attacker with root access to your file system before you even install it. This can include a number of threats, such as adding malicious certificates and performing man-in-the-middle traffic sniffing attacks, as well as disabling any protection you may have in place, such as your antivirus or your firewall.


The future of Windows is Copilot+, and currently it runs on Qualcomm Snapdragon

Microsoft revealed its vision for AI PCs, called Copilot+

Signed ISOs are much more secure

You may be thoughtfully wondering: how are Linux ISOs safe? The key element that keeps Linux ISOs secure is the checksum that comes with them. This checksum is generated in combination with a PGP key pair (normally), which allows developers of a distribution to publicly verify that they are who they say they are. This is called software signing, and installing unsigned software is likely to cause a set of “We cannot verify the developer of this software” warnings in your operating system.

These distributions are also open source, allowing the public to verify that the contents of an ISO are what they expect.

This all depends on how much you trust the original developers of the distribution, and this has been a problem for Linux distributions before, so there’s no guarantee of security, but these steps help mitigate risk and speed up community verification.

What should I use instead?

Post-installation modification is a much better idea

There are many great alternatives to downloading a custom Windows ISO. Your best bet is to use some sort of post-installation script that runs locally on your PC. These scripts are open source, so their content can be verified by the community and should not download any binaries directly – another vector of potential compromise.

There are great sample scripts for various things that can improve your Windows experience in a similar way to custom ISOs, but with much less risk. As with any potentially dangerous modification to your operating system like this, however, caution should be exercised. We encourage everyone to validate scripts themselves and only use scripts from trusted sources.

Here are some useful examples:


Win11Debloat is a simple PowerShell script that does what it says: removes a lot of bloat from your Windows operating system. Some of the benefits here include disabling telemetry, removing default apps, removing Bing and Copilot and much more. You can view the script on GitHub.

WinUtil by ChrisTitusTech

This one is technically a script, but it pushes the boundaries a bit. It has a fully functional GUI and a range of tweaks, tools, updates and configuration options. It is a complete one-stop-shop for optimizing your Windows installation in terms of unblocking and speed. There aren’t a lot of crazy game tweaks here, but there are some nice pre-configured options for security and updates.

This also has the advantage of being very simple to use and very accessible (thanks to its graphical interface). There’s also no need to download the script – it can be run with a single line from your Powershell terminal – although this isn’t necessarily the safest thing to do if you’re the cautious type.

You can check out WinUtil on GitHub.

You can always make your own

Screenshot of a Windows 11 desktop running MODWIN showing two ISO files, one official and one modified

In all of this, it is important to make a distinction. Custom Windows images are only dangerous because you can’t trust the person creating them – there’s no harm in creating your own. This is even something that has already been discussed on XDA. There’s also nothing stopping you from using some of the tools above and bundling the image yourself, before burning it to a USB stick or similar for repeat installations on all your PCs.

Unverified closed distributions are dangerous

Basically, closed Windows distributions are dangerous and you should avoid them. There are many examples – which we have avoided linking to specifically – but, regardless of the developer’s reputation, the lack of easy verification of their content makes these distributions inherently dangerous. If you are downloading Windows (or any other operating system), you should only use the site provided by the owner.

The type of exploits that can exist in these distributions can remain undetected for years, and you may never even notice they are there. It’s important to protect your home’s cybersecurity because the consequences can be disastrous and potentially life-changing.


Related posts