Method and computer system for preventing malicious software from attacking files of the computer system and corresponding non-transitory computer readable storage medium

A method for preventing malicious software from attacking files of a computer system includes the following steps. Whether a file type of a specific file corresponding to an input/output (I/O) requestis a to-be-backed-up file type is checked, wherein the to-be-backed-up file type belongs to one of multiple predetermined file types susceptible to malicious software attack. When the file type of the specific file is the to-be-backed-up file type, a backup already tag in a file context tag structure of the specific file is checked. When the backup already tag shows that the specific file has notbeen backed up, a backup process is performed for the specific file. 一种用于防御恶意软件攻击计算机系统的文件的方法，包括以下步骤。确认输入/输出(I/O)请求所对应的特定文件的文件类型是否为需备份的文件类型，需备份的文件类型属于易受恶意软件攻击的多个预设的文件类型中的一个。当特定文件的文件类型为需备份的文件类型时，检查特定文件的文件内容标签结构中的已完成备份标签。当已完成备份标签显示特定文件尚未完成备份时，对特定文件进行备份程序。