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I am studying for the CWSP and want to get an exact cost to an attacker attempting a brute-force attack on a WPA2-Personal WLAN. The textbook goes as far to say that WPA2-Personal is "vulnerable to an offline brute-force dictionary attack."

It wasn't clear to me exactly what resources are required for an attacker to mount such an attack, so I read over this page. It's good but there's nothing to verify the page's info against.

My question is simply: Where is a copy of the 802.11i specification I didn't see it on the IEEE website.

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As John already answered, 802.11i no longer exists as it has been superseded by a more recent standard, namely the 802.11-2007 standard. For the 802.11 working group, you can always find the status of standards by looking here.

You really need to review the document and parts of 802.11i may be in several places. From a very brief look at the table of contents, you may want to start with sections 5.4, 5.8 and 8. You will need to key in on sections relating to PSK and CCMP specifically, as WPA2, Personal, and Enterprise are terminology coined by the Wifi Alliance, not the IEEE.

Even without reviewing the document, it is a fairly easy concept to understand the vulnerability. Equate this to a file that is AES encrypted with a static password. If someone were to get a copy of the file, all they needed to do to decrypt it would be to brute force decrypting the file until they found a password that produces meaningful output.

If someone captures the connection handshake on a PSK network, this is exactly the same process. This may not be quick and take lots of processing resources, it can be done.

As to what resources are necessary to perform such an attack, you may want to look into the BackTrack distribution. This is a distribution targeted at security/penetration testing and there are several books and many documents describing how to use the tools within for all kinds of security applications.

Edit: I should have mentioned, while 802.11-2007 rolled up802.11i, the current standard is 802.11-2012 and this is a roll up of 802.11-2007 and and the amendments between.

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802.11i was an amendment to the 1999 802.11 standard, rather than a separate standard. 802.11-2007 was created to roll up that and 7 other amendments (a, b, d, e, g, h, i, j).

Edit: Here's the wikipedia page.

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  • Links to PDFs like that are just what I was looking for. I downloaded the PDF but didn't find anything specific to 802.11i or WPA2 in there. Can these be found in another document? – T. Webster May 25 '13 at 11:36
  • WPA and WPA2 are not IEEE standards. They are from the WiFi Alliance, and I believe you have to be a member to obtain their standards. The contents of 802.11i amendment are actually in the 802.11-2007 and 802.11-2012 standard documents and would not be called out as 802.11i, as the amendments have been retired. – scottm32768 May 25 '13 at 14:28

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