Malware refers to software that is designed to be invasive and cause harm. Types of malware include viruses, trojan horses, worms, ransomware, adware, scareware, spyware, and other malicious software programs that attempt to subvert a computer, website, web application, or network.
To continue operating covertly, malware may be designed to parasitically live within a program or system undetected. While ransomware uniquely operates to root in and then disclose its existence, most viruses and malicious programs benefit by this concealed existence, continually rerouting, corrupting, or taking information.
Acting much like malware itself, anti-malware software bores deep into an operating system and looks for indicators that show suspicious or unauthorized programs may be present. Other indicators may be as insignificant, at first glance, as slow network or application speeds. And, malware can exploit legitimate programs and applications, like the Android hack that infected 14 million smartphones.