Did you just find a file that has a digital signature from mst software GmbH? If that's the case, please read on.
You will probably see mst software GmbH when running the file. The publisher name shows up as the "Verified publisher" in the UAC dialog as the screengrab shows:

You can view the digital signature details for mst software GmbH with the following steps:
Here is a screenshot of a file that has been digitally signed by mst software GmbH:

As you can see in the screenshot above, Windows reports that "This digital signature is OK". This means that the file has been published by mst software GmbH and that no one has tampered with the file.
If you click the View Certificate button shown in the screenshot above, you can see all the details of the certificate, such as when it was issued, who issued the certificate, how long it is valid, etc. You can also examine the address for mst software GmbH, such as the street name, city and country.
GlobalSign ObjectSign CA has issued the mst software GmbH certificates. You can also examine the details of the issuer by clicking the View Certificate button shown in the screengrab above.
The following are the mst software GmbH files I've collected, thanks to the FreeFixer users.
| Detection Ratio | File Name |
|---|---|
| 0/41 | mstDfrgB.exe |
The detection percentage is based on the fact that I've collected 41 scan results for the mst software GmbH files. 0 of these scan reports came up with some sort of detection. If you like, you can view the full details of the scan reports by examining the files listed above.
The analysis is based on certificates with the following serial numbers: