Injection attacks on 802.11n MAC frame aggregation

The ability to inject packets into a network is known to be an important tool for attackers: it allows them to exploit or probe for potential vulnerabilities residing on the connected hosts. In this paper, we present a novel practical methodology for injecting arbitrary frames into wireless networks, by using the Packet-In-Packet (PIP) technique to exploit the frame aggregation mechanism introduced in the 802.11n standard. We show how an attacker can apply this methodology over a WAN -- without physical proximity to the wireless network and without requiring a wireless interface card. The practical feasibility of our injection method is then demonstrated through a number of proof-of-concept attacks. More specifically, in these proof-of-concepts we illustrate how a host scan can be performed on the network, and how beacon frames can be injected from a remote location. We then both analytically and experimentally estimate the success rate of these attacks in a realistic test setup. Finally, we present several defensive measures that network administrators can put in place in order to prevent exploitation of our frame injection methodology.