linux – How can data from VirtualBox leak to the host and how to avoid it?

There are several possible explanations for the recovery of the pictures from your virtual machine:

Virtual machine images can be cached by the host system. This means that when you view the virtual machine on your host, a cached version of the image is stored on the host’s disk. If this cache is not cleared properly, it may contain sensitive data.

Swap files are another possible explanation. Swap files are used by the host operating system to store temporary data when there is not enough physical memory available. If the virtual machine’s memory is swapped to the host’s swap file, it may contain sensitive data.

Shared folders can also be a potential source of data leakage. If you shared a folder between your virtual machine and your host operating system, it may contain sensitive data.

It’s important to note that virtual machine guest additions and shared folders can introduce security risks, as you mentioned. You should avoid using shared folders or guest additions whenever possible, especially for sensitive data.

To prevent leaks like this in the future, you should:

Encrypt the virtual machine’s disk image using a strong encryption algorithm.

Use a virtual machine manager that allows you to encrypt the virtual machine’s memory and swap files.

Do not use shared folders or guest additions, especially for sensitive data.

Use a secure erase tool to wipe the virtual machine’s free space before deleting it.

Be sure to securely delete the virtual machine image from your host system when you no longer need it.

It’s important to note that even with these precautions, there is still a risk of data leakage. State-level actors have access to powerful tools and techniques for recovering deleted data, so it’s important to take additional measures to protect sensitive information.