Did you just find a download or a file on your computer that has a digital signature from STMicroelectronics? If so, please read on.
You will probably notice STMicroelectronics when double-clicking to run the file. The publisher name shows up as the "Verified publisher" in the UAC dialog as the screenshot shows:

You can view additional details from the STMicroelectronics certificate with the following steps:
Here is a screengrab of a file that has been signed by STMicroelectronics:

As you can see in the screenshot above, Windows reports that "This digital signature is OK". This implies that the file has been published by STMicroelectronics and that the file has not been tampered with.
If you click the View Certificate button shown in the screenshot above, you can view 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 examine the address for STMicroelectronics, such as the street name, city and country.
VeriSign Class 3 Code Signing 2009-2 CA, VeriSign Class 3 Code Signing 2010 CA and VeriSign Class 3 Code Signing 2004 CA has issued the STMicroelectronics certificates. You can also examine the details of the issuer by clicking the View Certificate button shown in the screencap above.
The following are the STMicroelectronics files I have collected, thanks to the FreeFixer users.
| Detection Ratio | File Name |
|---|---|
| 0/38 | stdcfltn.sys |
| 0/51 | stdcfltn.sys |
| 0/48 | stdcfltn.sys |
| 0/48 | FF_Protection.exe |
| 0/47 | FF_Protection.exe |
| 0/42 | stdcfltn.sys |
| 0/57 | stdcfltn.sys |
| 0/48 | FF_Protection.exe |
| 0/46 | stdflt.sys |
| 0/42 | stdcfltn.sys |
The detection percentage is based on that I have gathered 1309 scan reports for the STMicroelectronics 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 has been done on certificates with the following serial numbers: