1. A method of determining whether an executable file is malware by using network behavioral artifacts, the method comprising: identifying a training corpus comprising plurality of benign executable files and a plurality of malware executable files; associating, by an electronic hardware processor, each of a plurality of network behavioral artifacts with a respective character set; assigning, by an electronic hardware processor, each executable file from the training corpus a respective string of character sets, wherein each string of character sets represents temporally ordered network behavior artifacts of a respective executable file from the training corpus, whereby a plurality of strings of character sets is obtained; obtaining, by an electronic hardware processor, for each of the plurality of strings of character sets and for a fixed n>1, a respective set of contiguous substrings of length n; ordering, by an electronic hardware processor, a union of the respective sets of contiguous substrings of length n, whereby an ordered universe of contiguous substrings of length n is obtained; forming, for each executable file from the training corpus and by an electronic hardware processor, a respective feature vector, wherein each respective feature vector comprises a tally list comprising counts of contiguous substrings of length n in the respective set of contiguous n-grams for the respective executable file from the training corpus, whereby a plurality of feature vectors is obtained; classifying, by an electronic hardware processor, each respective feature vector of the plurality of feature vectors as associated with either a benign executable file or a malware executable file from the training corpus, whereby a set of classified feature vectors is obtained; training a machine learning system with the set of classified feature vectors, wherein the machine learning system comprises an electronic hardware processor; identifying an unknown executable file; generating, by an electronic hardware processor, a feature vector for the unknown executable file; submitting the feature vector for the unknown executable file to the machine learning system; obtaining, by an electronic hardware processor, a classification of the unknown executable file as one of likely benign and likely malware; and outputting, by an electronic hardware processor, the classification of the unknown executable file.