Boot scans, also called shoe scans or pre-boot viruses scans, are sophisticated tools that antimalware software uses to find and eliminate malware that has not been detected by standard scanning programs. This type scan can be scheduled to run automatically on a regular basis, or manually by the user if they suspect that their computer has been infected. Many antivirus programs allow users to choose the sensitivity of the boot scan and also decide on the actions that should be taken if the threat is identified.

The reason a boot scan can be so efficient is because it permits the antimalware program to identify files that are used by the operating system. These types of files are unable to be deleted since they are always being used by the OS and will give an Access Denied error when attempts are made to remove them. The boot scan will discover these files and permit the antivirus software to erase them before the OS is able to begin using them.

The duration of a boot-scan will differ based on a variety of factors, such as the speed of the scan and the number of system files that are being scan. It also is contingent on whether the machine is running during the scanning process. It is however common for this type scan to take a lot longer than a typical antivirus scan because of the comprehensive nature of the process.