Did you just run into a download or a file on your computer that has a digital signature from fassurun? Some of the security products refers to the detected files as Gen:Variant.Adware.SwiftBrowse.1 and Trojan ( 004af26b1 ). The detection rate for the fassurun files collected here is 36%. Please read on for more details.
You'll probably notice fassurun when double-clicking to run the file. The publisher name is then displayed as the "Verified publisher" in the UAC dialog as the screencap shows:

You can also view the fassurun certificate with the following procedure:
Here is a screenshot of a file that has been digitally signed by fassurun:

As you can see in the screengrab above, Windows reports that "This digital signature is OK". This means that the file has been published by fassurun 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, and so on. You can also view the address for fassurun, such as the street name, city and country.
VeriSign Class 3 Code Signing 2010 CA has issued the fassurun certificates. You can also view the details of the issuer by clicking the View Certificate button shown in the screenshot above.
These are the fassurun files I've gathered, thanks to the FreeFixer users.
| Detection Ratio | File Name |
|---|---|
| 5/49 | updatefassurun.exe |
| 33/56 | maintainer.exe |
Here is the detection names for the fassurun files. I've grouped the detection names by each scanner engine. Thanks to VirusTotal for the scan results.
| Scanner | Detection Names |
|---|---|
| AVG | Generic6.DAP |
| AVware | Yontoo (fs) |
| Ad-Aware | Gen:Variant.Adware.SwiftBrowse.1 |
| AhnLab-V3 | Adware/Win32.SwiftBrowse |
| Antiy-AVL | GrayWare[AdWare:not-a-virus]/Win32.Yotoon.bfm |
| Avast | Win32:Adware-BYZ [PUP] |
| Avira | ADWARE/BrowseFox.Gen7 |
| Baidu-International | Adware.Win32.BrowseFox.fass |
| BitDefender | Gen:Variant.Adware.SwiftBrowse.1 |
| Bkav | W32.ArtemisJwlvlA.Trojan |
| CAT-QuickHeal | AdWare.Yotoon.A5 |
| ClamAV | Win.Adware.Agent-22685 |
| Comodo | Application.Win32.BrowseFox.B |
| DrWeb | Trojan.BPlug.281 |
| ESET-NOD32 | a variant of Win32/BrowseFox.G, Win32/BrowseFox.V |
| Emsisoft | Gen:Variant.Adware.SwiftBrowse.1 (B) |
| F-Prot | W32/A-de841313!Eldorado |
| F-Secure | Gen:Variant.Adware.SwiftBrowse.1 |
| GData | Gen:Variant.Adware.SwiftBrowse.1 |
| Ikarus | AdWare.SwiftBrowse |
| K7AntiVirus | Trojan ( 004af26b1 ) |
| K7GW | Trojan ( 004af26b1 ) |
| Kaspersky | not-a-virus:AdWare.Win32.Yotoon.bfm |
| Kingsoft | Win32.Troj.Generic.a.(kcloud) |
| Malwarebytes | PUP.Optional.SwiftBrowse |
| McAfee | Artemis!4712EBBDE67B, BrowseFox-FTR |
| McAfee-GW-Edition | Artemis!4712EBBDE67B, BehavesLike.Win32.Downloader.ch |
| MicroWorld-eScan | Gen:Variant.Adware.SwiftBrowse.1 |
| NANO-Antivirus | Riskware.Win32.Kranet.dgiwfc |
| SUPERAntiSpyware | Adware.SwiftBrowse |
| TrendMicro-HouseCall | TROJ_GEN.F47V1122 |
| VBA32 | AdWare.Yotoon |
| VIPRE | Yontoo (fs) |
| Zillya | Adware.Kranet.Win32.476 |
| nProtect | Trojan-Clicker/W32.Yotoon.123672 |
The detection percentage is based on that I have gathered 105 scan reports for the fassurun files. 38 of these scan results 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 has been done on certificates with the following serial numbers: