Email
Like bacteria in a petri dish of warm sugar water, malware thrives in a computing environment full of unsecured P2P networking, remotely exploitable vulnerabilities, and free-flowing e-mail attachments. According to Symantec's recent Global Internet Security Threat Report, the following means of propagation are most popular amongst malicious hackers. Because hackers usually use more than one means of propagation, the percentages add up to over 100 percent.