![]() The portal is an easy target that, if compromised, can completely block the access to the service.Ī better but more difficult way to jam a Wi-Fi network is to prevent one or all the stations on a network from transmitting. But open APs are also an essential part of public Wi-Fi hotspots, free or fee-based, which rely on an open connection portal. This wouldn’t be a serious concern if open APs were only owned by unwary individuals. Needless to say, the 802.11w does nothing to protect open (unencrypted) Access Points. This leaves a significant part of the installed base unprotected against management frames forgery. The 802.11w does help, but there’s a catch: even several years after the ratification of the 802.11w amendment, many commercial Wi-Fi devices don’t implement it, or have it turned off by default to preserve interoperability with older stations and/or it(s poorly implemented. This amendment brought significant security improvements, especially by encrypting management frames, and providing mechanisms to ensure data integrity and authenticity. The popular hacking suite AirCrack even had a special utility generating this kind of attack with just a command line on a laptop or a hacked smartphone. Many scenarios have been devised to improve the effectiveness and the stealthiness of the attack, but they all rely on this same basic principle.īefore the 2009 version of the 802.11 standard, management frames were not encrypted, making this kind of attack very simple and effective even on protected networks. The original intent is to attempt a graceful exit and to free internal resources. Of course, these frame types do have a legitimate usage: in normal operation, stations use them in order to let the Access Point know that they are about to leave the network, while Access Points use them to disconnect a station for whatever reason. Disassociation frames are preferred in open networks (unencrypted) while the Deauthentication frames are used in protected networks. To do so, the attacker forges a Disassociation or Deauthentication frame where the source address is the Access point’s and the destination is the victim’s. Also known as DISASSOC/DEAUTH flooding – named after specific type of management frames which can effectively be forged – the basic principle is to let the victim believe that it has been excluded from the network. The legitimate Wi-Fi stations can even help in locating the jamming device if they can provide RSSI data.įorging management frames has long been a popular way to disrupt the operation of an individual station or of an entire Wi-Fi network. But there is good news: the source of the signal is fairly easy to locate, e.g. There are DIY video tutorials on how to build your own! Additionally, there is very little you can do to counter a signal jammer. ![]() The main problem with the signal jammers is that they are very accessible, affordable and annoying. Some more elaborate devices do noise shaping to restrict the interference to angle channel, or generate bursts instead of continuous noise. As the Wi-Fi bands are fairly large, a signal jammer often features a set of three to five external antennas of different sizes. The basic models simply transmit White noise across the spectrum and blind the receiving stations operating in this frequency range. ![]() In its simplest form, a Wi-Fi signal jammer basically transmits a high power signalin the same band as the Wi-Fi device being targeted. Here is a sampler of common jamming techniques, and counter-measures. Let’s defer the discussion on whether Wi-Fi jamming is legitimate (yes, it is), and focus on the technical aspects. Among the wireless networks, Wi-Fi has become so ubiquitous and relied upon that just associating the words Wi-Fi and jamming is unacceptable.īut jamming can also be desirable and even ethical, although a different terminology is used in such instances (spectrum management?). The FCC has banned jamming, it’s used by repressive regimes, it can shut down facilities and can be used to intercept private communications. Jamming has a negative connotation when used in a wireless context. May 1st, 2015 – A Primer On Wi-Fi Jamming ![]()
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