For the past several years Buffer Overflow attacks have been the main method of compromising a computing system's security. Many of these attacks have been devastatingly effective, allowing the attacker to attain administrator privileges on the attacked system. We review the anatomy of these attacks and the reasons why conventional methods of defense have been ineffective, and likely to remain so in the foreseeable future. Recently, however, several promising methods of defense have been proposed. We compare the strengths and weaknesses of these defense methods.