On Blowback Traffic on the Internet

Abstract

This paper considers the phenomenon where a single probe to a target generates multiple, sometimes numerous, packets in response -- which we term "blowback". Understanding blowback is important because attackers can leverage it to launch amplified denial of service attacks by redirecting blowback towards a victim. Blowback also has serious implications for Internet researchers since their experimental setups must cope with bursts of blowback traffic. We find that tens of thousands, and in some protocols, hundreds of thousands, of hosts generate blowback, with orders of magnitude amplification on average. In fact, some prolific blowback generators produce millions of response packets in the aftermath of a single probe. We also find that blowback generators are fairly stable over periods of weeks, so once identified, many of these hosts can be exploited by attackers for a long time.