How Is Malware Spread?
Cybercriminals constantly devise innovative means to get malware onto your computer. Here are some of the most common ways that malware, including viruses, worms, Trojans, and spyware, can be spread:
- Email: Cybercriminals are notorious for including malicious attachments and links in emails that appear to come from friends, reputable organizations, or other trusted sources. Some malicious emails can even infect your computer from the email client’s preview pane, without your opening or downloading an attachment or a link.
- The Internet: Surfing the Web may feel like a private activity, but in fact you’re exposing your computer to unwanted contact with anyone else who has a computer and Internet access. All you have to do is visit a website or click a link and you’re a potential victim.
- Outdated software: Malware crawls the Internet, looking for vulnerabilities of outmoded software to spread its influence over computer systems. Be especially careful if you’re surfing the Web with outdated software (and update with the latest versions as soon as you can), including your browsers, operating systems, or system plug-ins.
- Local Area Networks (LANs): A LAN is a group of locally connected computers that can share information over a private network. If one computer becomes infected with malware, all other computers in the LAN may quickly become infected as well.
- Instant messaging (IM) and peer-to-peer (P2P) file-sharing systems: If you’re using a client for these online activities, malware may spread to your computer.
- Social networks: Malware authors take advantage of many popular social networks, infecting the massive user-data networks with worms. If a social website account is infected with a worm, just about anyone who visits a poster’s profile page could “catch” the worm on her system.
- Pop-ups: Some of the most sophisticated malware spreads through well-disguised screen pop-ups that look like genuine alerts or messages. One particularly devious—and widespread—“hoax pop-up” claims to have scanned your computer and detected malware. If you attempt to remove the malware as urged, you’ll actually install the malware.
- Computer storage media: Malware can be easily spread if you share computer storage media with others, such as USB drives, DVDs, and CDs. While it may seem safe to open a CD of photos from a colleague, it’s always best to scan unfamiliar files first for possible corruptions or security risks before you copy or open them.
- Mobile devices: Mobile malware threats have become increasingly prevalent (see Chapter 6, “INSERT CHAPTER TITLE”), as more people use their smartphones and tablets as mini-computers, helping malware problems proliferate across additional platforms.