City University London researcher Florian Adamsky warns vulnerabilities in BitTorrent Sync and BitTorrent clients can be exploited to launch a Distributed Reflective Denial of Service (DRDoS).
In his paper called ‘P2P File-Sharing in Hell: Exploiting BitTorrent Vulnerabilities to Launch Distributed Reflective DoS Attacks', Adamsky illustrates how uTP, DHT, Message Stream Encryption and BitTorrent Sync protocol vulnerabilities can be abused by an attacker to amplify Denial of Service attacks.
The IP spoofing exploit is most effective via peer-to-peer file sync tool BitTorrent Sync, where an attacker can amplify his bandwidth by a factor of 120. Popular BitTorrent clients like µTorrent and Vuze yield bandwidth increases of 39 and 54 times, respectively.
Speaking with TF, Adamsky states that it’s relatively easy to carry out a distributed reflective Denial of Service (DRDoS) attack via BitTorrent. The attacker only needs a valid info-hash, or the “secret” in case of BitTorrent Sync.
“This attack should not be so hard to run, since an attacker can collect millions of possible amplifiers by using trackers, DHT or PEX,” he explains.
“With a single BitTorrent Sync ping message, an attacker can amplify the traffic up to 120 times.”
For BitTorrent users, the security risk is limited to unwittingly participating in a DoS attack, which can lead to a lot of wasted bandwidth. BitTorrent has been notified about the issues and patched some in a recent beta release, but µTorrent is still vulnerable to DHT attack. Vuze has yet to release an update.