The document discusses the definition and impact of malware, specifically focusing on trojan horse viruses, which disguise themselves as legitimate programs to gain unauthorized access to computer systems. It outlines common methods for infection through social engineering tactics, such as deceptive email attachments and social media advertisements. To mitigate attacks, it recommends measures including the installation of anti-malware software, regular system updates, scanning external devices, and exercising caution with untrusted programs and email attachments.