A flaw discovered in several widely used BitTorrent applications could be used to carry out a devastating distributed denial of service (DDoS) attack that makes it very easy for a single undetectable hacker to bring down large sites. Researchers conducted a test in which they were able to exploit BitTorrent peers to flood a third-party target with data traffic up to a factor of 50 to 120 times bigger than the original request. The vulnerability affects BitTorrent protocols (Micro Transport Protocol (uTP), Distributed Hash Table (DHT), Message Stream Encryption (MSE) and BitTorrent Sync (BTSync) protocols.
Source: https://thehackernews.com/2015/08/bittorrent-dos-attack.html