Practical evaluation of passive COTS eavesdropping in 802.11b/n/ac WLAN

Daniele Antonioli, Sandra Siby, Nils Ole Tippenhauer

Research output: Chapter in Book/Report/Conference proceedingConference contribution


In this work, we compare the performance of a passive eavesdropper in 802.11b/n/ac WLAN networks. In particular, we investigate the downlink of 802.11 networks in infrastructure mode (e. g. from an access point to a terminal) using Commercial-Of-The-Shelf (COTS) devices. Recent 802.11n/ac amendments introduced several physical and link layer features, such as MIMO, spatial diversity, and frame aggregation, to increase the throughput and the capacity of the channel. Several information theoretical studies state that some of those 802.11n/ac features (e. g. beamforming) should provide a degradation of performance for a passive eavesdropper. However, the real impact of those features has not yet been analyzed in a practical context and experimentally evaluated. We present a theoretical discussion and a statistical analysis (using path loss models) to estimate the effects of such features on a passive eavesdropper in 802.11n/ac, using 802.11b as a baseline. We use Signal-to-Noise-Ratio (SNR) and Packet-Error-Rate (PER) as our main metrics. We compute lower and upper bounds for the expected SNR difference between 802.11b and 802.11n/ac using high-level wireless channel characteristics. We show that the PER in 802.11n/ac increases up to 98% (compared to 802.11b) at a distance of 20 m between the sender and the eavesdropper. To obtain a PER of 0.5 in 802.11n/ac, the attacker’s maximal distance is reduced by up to 129.5 m compared to 802.11b. We perform an extensive set of experiments, using COTS devices in an indoor office environment, to verify our theoretical estimations. The experimental results validate our predicted effects and show that every amendment add extra resiliency against passive COTS eavesdropping.

Original languageEnglish (US)
Title of host publicationCryptology and Network Security - 16th International Conference, CANS 2017, Revised Selected Papers
EditorsSrdjan Capkun, Sherman S.M. Chow
PublisherSpringer Verlag
Number of pages21
ISBN (Print)9783030026400
StatePublished - 2018
Event16th International Conference on Cryptology and Network Security, CANS 2017 - Hong Kong, China
Duration: Nov 30 2017Dec 2 2017

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Volume11261 LNCS
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349


Conference16th International Conference on Cryptology and Network Security, CANS 2017
CityHong Kong


  • 802.11
  • Beamforming
  • Eavesdropping
  • MIMO
  • WLAN

ASJC Scopus subject areas

  • Theoretical Computer Science
  • General Computer Science


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