certofsystem.exe is a malicious executable, which is designed to start a parasite or launch some of its components. If you discovered this file in the system, beware that it is mostly identified as a Trojan/Backdoor that is used to steal bank data and other sensitive people's information. Typically, such trojans hide deep inside the system and collect keyboard clicks. Once they collect a required amount of information, they send it to their remote control servers where scammers apply it for taking over loggins, passwords and similar data that could help them make money.
In addition, some security experts have reported that certofsystem.exe is also related to Advanced Defender, which is categorized as rogue anti-spyware. When infected with this virus, you may notice continuous pop-up advertisements that report about different kinds of viruses and then offer to buy Advanced Defender's version for their removal. Of course, this is just another technique used for stealing people's money.
As you can see, certofsystem.exe is a significant part of dangerous viruses that must be removed from the system before they steal your money or other sensitive information. Delaying removal of this file can easily lead you to privacy violation and computer's damage, so be sure you get rid of this file immediately after detection. For that we recommend using one of these programs: RegCure Pro, Reimage.