The speed, ubiquity, and anonymity of Internet media make them ideal for militant groups' communication, necessitating content analysis by intelligence agencies. This study modified an existing framework for analyzing online authorship and applied it to Arabic and English Web forum messages linked to extremist groups. A multilingual model tailored to Arabic's unique features and a complex message extraction component were developed. These tools assist in identifying patterns of terrorist communication by evaluating linguistic features and comparing them to known writing styles.