It doesn't matter what side of the copyright bench you sit on, filesharing is dangerous. Before you roll your eyes and say "Yeah, whatever...", here are the three most common misconceptions about filesharing safety.
1. It came from someone I know a.k.a. I only download from trusted sources.
Filesharing worms are programmed to copy themselves to folders used by popular peer-to-peer (P2P) filesharing apps such as KaZaA, Gnutella, Morpheus and dozens of others. The worms do this by searching for folders that have specific strings in the foldername. And when the worm copies itself to the folder, it does so using filenames of popular downloads. The end result: that bootleg copy of GuitarHero you found on a 'trusted' filesharing source is much more likely to be a worm and not a copy of GuitarHero.
2. It's just a worm and worms don't do damage.
Filesharing worms do much more than promiscuously make copies of themselves. Once seated on your system, they also download additional malware, including password stealers and backdoors that siphon the login credentials you use for email, IM, MySpace, Facebook, online banking, and more. As a final insult, the worm will then copy itself to filesharing folders on your computer so it can trick your own friends into trusting that it's safe to download.
3. BitTorrent is a safe alternative to traditional P2P filesharing.This gets a big sort of as torrents are only (very) slightly safer. BitTorrent can also lead to the spread of malware, but it requires the attackers to deliberately seed the malicious files. Since that requires time and effort on the part of the attackers, it's not as prolific a source as the worm-spread found on traditional P2P filesharing networks such as KaZaA, Gnutella, LimeWire and Morpheus. Still, the MPAA has been known to upload backdoors disguised as popular movies in order to snare file sharers, and criminals commonly spoof popular rippers to disguise their malware as well.
For optimum computer security, avoid all forms of filesharing like the plague. Otherwise, it's not a matter of if you get infected, but when.
