Did you just run into a file that has a digital signature from MKS Sp. z o.o.? If so, please read on.
You will typically see MKS Sp. z o.o. when double-clicking to run the file. The publisher name is then displayed as the "Verified publisher" in the UAC dialog as the screengrab shows:

You can view additional details from the MKS Sp. z o.o. certificate with the following procedure:
Here is a screenshot of a file that has been digitally signed by MKS Sp. z o.o.:

As you can see in the screenshot above, the Windows OS reports that "This digital signature is OK". This means that the file has been published by MKS Sp. z o.o. and that no one has tampered with the file.
If you click the View Certificate button shown in the screenshot above, you can examine all the details of the certificate, such as when it was issued, who issued the certificate, how long it is valid, and so on. You can also view the address for MKS Sp. z o.o., such as the street name, city and country.
VeriSign Class 3 Code Signing 2009-2 CA has issued the MKS Sp. z o.o. certificates. You can also view the details of the issuer by clicking the View Certificate button shown in the screenshot above.
These are the MKS Sp. z o.o. files I've collected, thanks to the FreeFixer users.
| Detection Ratio | File Name |
|---|---|
| 0/54 | mksfwallf.sys |
The detection percentage is based on the fact that I have collected 54 scan results for the MKS Sp. z o.o. files. 0 of these scan reports came up with some sort of detection. You can review the full details of the scan reports by examining the files listed above.
The analysis is based on certificates with the following serial numbers: