"Malware, also known as malicious code and malicious software, refers to a program that is inserted into a system, usually covertly, with the intent of compromising the confidentiality, integrity, or availability of the victim's data, applications, or operating system or otherwise annoying or disrupting the victim. Malware has become the most significant external threat to most systems, causing widespread damage and disruption, and necessitating extensive recovery efforts within most organizations...This publication provides recommendations for improving an organization's malware incident prevention measures. It also gives extensive recommendations for enhancing an organization's existing incident response capability so that it is better prepared to handle malware incidents, particularly widespread ones. The recommendations address several major forms of malware, including viruses, worms, Trojan horses, malicious mobile code, blended attacks, spyware tracking cookies, and attacker tools such as backdoors and rootkits. The recommendations encompass various transmission mechanisms, including network services (e.g., e-mail, Web browsing, file sharing) and removable media."