Wireless Networking ALERT: WPA isn't necessarily secure

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Subject Author Date
ALERT: WPA isn't necessarily secure John Navas 10-16-06
Posted by John Navas on October 16, 2006, 4:59 pm
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SUMMARY:

WPA-PSK is vulnerable to offline attack.

TO AVOID THE PROBLEM:

USE A PASSPHRASE WITH MORE THAN 20 CHARACTERS. Examples:
BAD: "vintage wine"
GOOD: "floor hiking dirt ocean"
(pick your own words, even longer is better)
FOR HIGH SECURITY, USE MORE THAN 32 CHARACTERS.

BACKGROUND:

Weakness in Passphrase Choice in WPA Interface
By Glenn Fleishman
By Robert Moskowitz
Senior Technical Director
ICSA Labs, a division of TruSecure Corp
<http://wifinetnews.com/archives/002452.html>

...
The offline PSK dictionary attack
...
Just about any 8-character string a user may select will be in the
dictionary. As the standard states, passphrases longer than 20 characters
are needed to start deterring attacks. This is considerably longer than
most people will be willing to use.

This offline attack should be easier to execute than the WEP attacks.
...
Using Random values for the PSK

The PSK MAY be a 256-bit (64 hexadecimal) random number. This is a large
number for human entry; 20 character passphrases are considered too long
for entry. Given the nature of the attack against the 4-Way Handshake, a
PSK with only 128 bits of security is really sufficient, and in fact
against current brute-strength attacks, 96 bits SHOULD be adequate. This is
still larger than a large passphrase ...
...
Summary
...
Pre-Shared Keying is provided in the standard to simplify deployments in
small, low risk, networks. The risk of using PSKs against internal attacks
is almost as bad as WEP. The risk of using passphrase based PSKs against
external attacks is greater than using WEP. Thus the only value PSK has is
if only truly random keys are used, or for deploy testing of basic WPA or
802.11i functions. PSK should ONLY be used if this is fully understood by
the deployers.

See also:
Passphrase Flaw Exposed in WPA Wireless Security
<http://www.technewsworld.com/story/32070.html>

Wi-Fi Protected Access. Security in pre-shared key mode
<http://en.wikipedia.org/wiki/Wi-Fi_Protected_Access>

Cracking Wi-Fi Protected Access (WPA)
<http://www.ciscopress.com/articles/article.asp?p=369221>
<http://www.ciscopress.com/articles/article.asp?p=370636&rl=1>

WPA Cracker
<http://www.tinypeap.com/html/wpa_cracker.html>

Posted by Warren Oates on October 16, 2006, 5:13 pm
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> USE A PASSPHRASE WITH MORE THAN 20 CHARACTERS. Examples:
> BAD: "vintage wine"
> GOOD: "floor hiking dirt ocean"
> (pick your own words, even longer is better)
> FOR HIGH SECURITY, USE MORE THAN 32 CHARACTERS.

There's some discussion here, and a pretty cool password generator:

https://www.grc.com/passwords.htm

I know that not everyone loves GRC, but I run a Mac anyway, so I don't
care, and my router has all my ports stealthed.
--
W. Oates
Teal'c: He is concealing something.
O'Neil: Like what?
Teal'c: I am unsure, he is concealing it.

Posted by John Navas on October 16, 2006, 5:37 pm
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On Mon, 16 Oct 2006 17:13:54 -0400, Warren Oates

>
>> USE A PASSPHRASE WITH MORE THAN 20 CHARACTERS. Examples:
>> BAD: "vintage wine"
>> GOOD: "floor hiking dirt ocean"
>> (pick your own words, even longer is better)
>> FOR HIGH SECURITY, USE MORE THAN 32 CHARACTERS.
>
>There's some discussion here, and a pretty cool password generator:
>
>https://www.grc.com/passwords.htm
>
>I know that not everyone loves GRC, ...

Count me among them -- Steve Gibson (aka GRC) is a shameless snake oil
salesman with no real expertise in security, and the password generator
on the GRC site is of dubious quality and value.

Use Password Safe instead, created by noted cryptographer Bruce
Schneier, and subjected to open source scrutiny.

--
Best regards, FAQ for Wireless Internet: <http://Wireless.wikia.com>
John Navas FAQ for Wi-Fi: <http://wireless.wikia.com/wiki/Wi-Fi>
Wi-Fi How To: <http://wireless.wikia.com/wiki/Wi-Fi_HowTo>
Fixes to Wi-Fi Problems: <http://wireless.wikia.com/wiki/Wi-Fi_Fixes>

Posted by Warren Oates on October 16, 2006, 7:28 pm
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> Count me among them -- Steve Gibson (aka GRC) is a shameless snake oil
> salesman with no real expertise in security, and the password generator
> on the GRC site is of dubious quality and value.
>
> Use Password Safe instead, created by noted cryptographer Bruce
> Schneier, and subjected to open source scrutiny.

Looks good, but it's a Windows program. I've got XP running in a VM, but
I really hate it.
--
W. Oates
Teal'c: He is concealing something.
O'Neil: Like what?
Teal'c: I am unsure, he is concealing it.

Posted by Neill Massello on October 16, 2006, 9:37 pm
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> Looks good, but it's a Windows program. I've got XP running in a VM, but
> I really hate it.

Here are a couple of Mac utilities.

<http://www3.autistici.org/rpg/>
<http://macpasswordgenerator.com/password_generator>


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