A Late Multi-Modal Fusion Model for Detecting Hybrid Spam E-mail

TL;DR

This paper introduces a late multi-modal fusion model utilizing CNN and CBOW features combined with machine learning classifiers to improve hybrid spam email detection, addressing OCR limitations in speed and reliability.

Contribution

The study proposes a novel late fusion framework for hybrid spam detection that outperforms classical OCR-based early fusion methods, integrating CNN and CBOW features with various classifiers.

Findings

Effective detection of hybrid spam emails.

Improved speed over OCR-based methods.

Versatile classifier performance results.

Abstract

In recent years, spammers are now trying to obfuscate their intents by introducing hybrid spam e-mail combining both image and text parts, which is more challenging to detect in comparison to e-mails containing text or image only. The motivation behind this research is to design an effective approach filtering out hybrid spam e-mails to avoid situations where traditional text-based or image-baesd only filters fail to detect hybrid spam e-mails. To the best of our knowledge, a few studies have been conducted with the goal of detecting hybrid spam e-mails. Ordinarily, Optical Character Recognition (OCR) technology is used to eliminate the image parts of spam by transforming images into text. However, the research questions are that although OCR scanning is a very successful technique in processing text-and-image hybrid spam, it is not an effective solution for dealing with huge quantities due to the CPU power required and the execution time it takes to scan e-mail files. And the OCR techniques are not always reliable in the transformation processes. To address such problems, we propose new late multi-modal fusion training frameworks for a text-and-image hybrid spam e-mail filtering system compared to the classical early fusion detection frameworks based on the OCR method. Convolutional Neural Network (CNN) and Continuous Bag of Words were implemented to extract features from image and text parts of hybrid spam respectively, whereas generated features were fed to sigmoid layer and Machine Learning based classifiers including Random Forest (RF), Decision Tree (DT), Naive Bayes (NB) and Support Vector Machine (SVM) to determine the e-mail ham or spam.