1. A method comprising: storing trusted variables that pertain to prior scans for identifiers of undesirable code in a secure memory of a security subsystem, the secure memory being inaccessible to code executed by an operating system, the trusted variables comprising: a directory of files written to since a last scan; and a directory of files that have not been written to since the last scan; and accelerating a scan for identifiers of undesirable code by utilizing the trusted variables to reduce a number of files to be scanned and/or reduce a number of undesirable code identifiers used for scanning; wherein files written to since the last scan are scanned against all known identifiers of undesirable code; and wherein files that have not been written to since the last scan are scanned only against newly introduced identifiers of undesirable code.