Abstract: A scanning system for scanning computer files for exploits uses a database of validation rules, in respect of each of a plurality of file formats comprising data fields having a predetermined structure, the validation rules specifying valid structure and/or content for the data fields of the respective file format. Files are analysed to determine their file format. A validation process is performed comprising parsing the file to determine the structure and content of its data fields and validating the structure and/or content of the data fields of the file against the validation rules stored in the database in respect of the determined file format of the file. A file is determined to contain an exploit in response to the structure and/or content of the data fields of the file failing to be validated.

Abstract: Scanning of computer files for malware uses a classifying technique to classify an input file as a clean file or a dirty file. The parameters of the classifying technique are derived to train the classification on a corpus of reference files including clean files known to be free of malware and dirty files known to contain malware. The classification is performed using a representation of the files in a feature space defined by a set of predetermined features for respective file formats, the features being a predetermined value or range of values for one or more data fields of given meanings. The representation of a file is derived by determining the file format, parsing the file on the basis of the structure of data fields in the determined file format to identify the data fields and their meaning, and determining, on the basis of the identified data fields, which of the set of predetermined features are present.