On Jamming in Wireless Local Area Networks

MPhil Thesis Defence

Title: "On Jamming in Wireless Local Area Networks"

By

Mr. Liyi GU


Abstract

The shared nature of the medium in wireless networks makes them 
susceptible to all sorts of careless or malicious misbehaviour. Among 
them, jamming, which involves purposefully trying to interfere with the 
transmission and reception, is one of the major forms of attacks that can 
easily be staged in wireless local area networks (WLANs).

In this thesis we propose a new jamming attack on hidden nodes in WLANs. 
This attack deliberately targets uplink TCP acknowledgement packets 
(TCP-ACKs) of some downlink TCP flow as a means of increasing the 
throughput of the attacker(s). The jamming attack is designed in such a 
way that no modification to the wireless hardware is needed and it can be 
easily staged on commercial off-the-shelf wireless nodes. The attack 
consists of a series of well-coordinated stealth attacks on TCP traffic 
with the collective effect of degrading the target's throughput by causing 
occasional time-outs and by increasing its round-trip times (RTTs). In 
this attack, a rogue node first scans the channel for downlink traffic 
(from the AP), identifies one or several target nodes, then relies on our 
probabilistic estimation model to forecast the time when a transmission of 
jamming signal has a high likelihood of colliding with the target's 
generated TCP-ACKs. Repeating this process intelligently results in a 
decrease of the average window of the targeted TCP sender and an increase 
in its round-trip time, in addition to some occasional time-outs due to 
consecutive TCP-ACK losses. The rogue node and/or its colluding attackers 
can thus increase their TCP throughput. We conduct ns-2 protocol 
simulations to demonstrate the effectiveness of such attack and discuss 
its immunity to detection by existing detection schemes. We also identify 
some possible parameters that may be used in building future detection 
mechanisms to counter this attack.


Date:			Tuesday, 13 May 2014

Time:			2:00pm – 4:00pm

Venue:			Room 3501
 			Lifts 25/26

Committee Members:	Dr. Brahim Bensaou (Supervisor)
 			Dr. Jogesh Muppala (Chairperson)
 			Dr. Kai Chen


**** ALL are Welcome ****