Re: Dictionary and brute forcing web authentication?

[RSnake <rsnake () shocking com>]

        I wrote a paper on this topic and presented at BlackHat on this
specific topic, but from the other perspective... trying to secure a machine
under brute force HTTP attack.  It's a three part paper, and pretty in-depth,
but it should answer your questions.

http://www.securityfocus.com/infocus/1368
http://www.securityfocus.com/infocus/1369
http://www.securityfocus.com/infocus/1370

        The short of it is there are two basic ways to brute force.  Searching
for 200 or 401 return headers, and searching for strings on the page that is
returned.  WWWhack and Whisker both can perform these functions.  Read the
paper for more details.

On Sat, 13 Sep 2003, Chris Varenhorst wrote:

| Date: Sat, 13 Sep 2003 15:47:27 -0500
| From: Chris Varenhorst <hiyachris86 () hotmail com>
| To: webappsec () securityfocus com
| Subject: Re: Dictionary and brute forcing web authentication?
|
| Is it possible to just specify the failure string as a string from the login
| page?  The <title> tag works well especially since its likely that the login
| page, says something about how this is the login page in the title.  And as
| far as the password "popups" you mentioning happening in IE, you're right
| those most likely are NOT http application web authentication but http 401
| authentications which are part of the HTTP protocol.  I'm sure the query
| string "http authentication 401 brute force" in a Google and a little bit of
| time will find something to brute force those...
|
| >From: "Mark G. Spencer" <mspencer () evidentdata com>
| >To: <webappsec () securityfocus com>
| >Subject: Dictionary and brute forcing web authentication?
| >Date: Fri, 12 Sep 2003 12:55:41 -0700
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| >
| >I'm looking for advice on dictionary and brute forcing web authentication.
| >Most of the websites I have access to at work have various kinds of forms
| >based authentication.  I've been playing with a plugin for Sleuth
| >(httpbrute_plugin.zip) and am having difficulty.
| >
| >At a minimum I need to give the plugin the user and password fields from
| >the
| >source of the webpage so it knows where to perform the dictionary attack.
| >I
| >also need a failure string so the plugin knows when it has failed (and if
| >it
| >hasn't failed, theoretically succeeded), but herein lies the problem.  I'm
| >looking at a page called "securedefault.asp" .. When I enter a bogus
| >username and password, the login screen just displays again .. No special
| >failure message.
| >
| >Any ideas how to handle this?
| >
| >Also .. I noticed on some websites that as soon as you go to them, a user
| >and password box pops up.  I am not able to view source on these, either in
| >IE or Sleuth.  In IE the user and password box opens immediately, and in
| >Sleuth I get a Windows username and password box.  I'm assuming these are
| >*not* basic http authentication?  Any advice on how to dictionary attack
| >these things?
| >
| >Thanks!
| >
| >Mark
| >
|
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-R

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