ByteFence is a PUP that runs on Microsoft Windows. It is supposedly an authentic antivirus program.

It is usually installed onto the user's computer by being packaged in some freeware installation bundles. In some rare cases, it is impossible to remove the installer for ByteFence from other installation packages. ByteFence is considered a legitimate antivirus. Because of this, there is an official website for the program and it is possible for users to download the program there. It even states on the ByteFence website that ByteFence does find malware on the user's computer and doesn't go by false positives, however it does not remove malicious programs. ByteFence only tells the user that there may be some harmful programs on their computer. Unless they buy the premium version of the software, then ByteFence may be of no use as an antivirus.

Once downloaded, the program would change the user's homepage to ByteFence's search engine, which has redirects to Yahoo search results. Some bundled versions of ByteFence may come with a toolbar add-on. According to some users, ByteFence also displays advertisements on the user's computer, which may make it be adware, though this may be because ByteFence can be bundled with adware programs. It mainly consists of doing random scans of the user's computer that make pop-ups show up on the screen. In Windows 10, when clicking the arrow, a red dot and name change signifies malware on the ByteFence icon. It is removable via Control Panel.