Transcript WEP Poses Serious Risks to Retail

Connection handshake in WiFi
WiFi State Machine
-Amit Vartak
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WiFi Jargons
 AP (Access Point)
 Client/Station
 SSID
 WEP
 Infrastructure
 AdHoc
 Authentication
 Association
 MAC address
 IP address
 TKIP/ CCMP/ AES …
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Some Questions….
 What all you should know for getting
connected to AP?
 How Station comes to know the existence of
AP?
 How Station and AP negotiate the capabilities?
 Can AP check the credentials of Station and
vice versa?
 Does all this happen at layer #2 or layer #3?
 Since my AP is connected to ethernet jack…
Does ethernet and wireless frames share
same structure?
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Solution to above Questions…  
WiFi State Machine
Courtesy: IEEE 802.11-1999 standard
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Important Frames in Association (OPEN case)
 Beacon
 Probe Request
 Probe Response
 Authentication (From Client to AP)
 Authentication (Success/failure) (From AP to
Client)
 Association Request
 Association Response
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Importance of each frames
 Beacon
 Announce the existence
 Synchronization
 Probe request/ response
 Wireless credentials handshake
 Authentication
 Check the genuineness
 Association
 Can you server my needs?
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Shared key Authentication
 A shared secret between AP and Station
 Authentication phase now consists of 3 way
handshake
 AP authenticates the Station but Station
DOESNOT authenticate AP
 A simple challenge-response type of
authentication
 If you are using WEP… your first 128 byte key
stream for the IV is known to all..   
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WEP Association – any extra frame?
 NO, there is shared secret between AP and Station.
 Either party will use that secret for encryption
 Are you using WEP?
 First step is change it to WPA or WPA-2
 SecurityTube.net has videos for cracking WEP key
and flaws in WEP protocol… BUT first change your
security level… WEP is broken… its
Worst Ever Privacy… 
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-Thank You
-Amit Vartak
[email protected]
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