US Patent 11556644 Machine learning-based malicious attachment detector

In an embodiment, a computer-implemented method includes receiving, from a pre-processor, an output file; where the output file is created by the pre-processor in response to input of an electronic file to the pre-processor; where the electronic file is an attachment to a message that is in-transit to a recipient computer on a network; where the output file contains features that are created by the pre-processor analyzing one or more sub-features of the electronic file; receiving, from a machine learning-based classifier, malware classification data that indicates whether the electronic file does or does not contain malware; where the malware classification data is output by the machine learning-based classifier in response to the machine learning-based classifier determining that the features are or are not indicators of obfuscation; where data used to create the machine learning-based classifier includes output files previously created by the pre-processor; in response to the malware classification data matching a criterion, causing the network to modify, delay, or block transmission of the electronic file to the recipient computer.