Computer-implemented methods and system for preventing unauthorized file modification by malicious software and the like

A computer implemented cyber security method for preventing unauthorized modification to a file using an authorized handler, the method comprising the following steps:

• modifying a file attribute of the file to create a protected file, the file attribute configured to instruct a computer processor to permit write access of the protected file only by the authorized handler and to deny write access of the protected file by other programs;
• receiving a first write request, the first write request comprising an instruction set to be written to the protected file, the first write request unable to be written to the protected file and is instead transferred to the authorized handler which modifies an initial virtual file object to include the instruction set from the first write request, the initial virtual file object comprising merged data where the merged data comprises source data from the protected file and modification data from the instruction set of the write request;
• receiving a read request of the protected file;
• determining if there is an initial virtual file object associated with the protected file;
• determining if the initial virtual file object comprises merged data;
• and
• wherein, based on the determination of the initial virtual file object comprising merged data, returning only one of either (i) the merged data of the initial virtual file object and (ii) the source data of the protected file.