Malicious code infection system and malicious code infection method

Provided are a malicious code diagnosing system and a method of diagnosing malicious codes. According to embodiments of the present disclosure, a malicious code diagnosing operation is performed only on files that are likely to be infected by malicious codes by utilizing file change log information recorded in a file system. Accordingly, malicious code diagnosing operation can be performed more quickly and reliably than conventional diagnosing method.