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[NSE] http matching library
From: Patrik Karlsson <patrik () cqure net>
Date: Sat, 30 Apr 2011 08:49:54 +0200

Given the recent increase in http/web scripts I thought I would put some work out on the list I did a while back.
I started working on it right about the time Ron did his big overhaul of the http-enum script. [1]
My idea was to implement what the http-enum script does today, but de-couple the probes and matches from each other. 
The response wasn't very positive at the time.

Anyway, I did some more work on it and ended up creating a http-match library which pretty much does regexp matching 
based on rules created on-the-fly or loaded from a file.
There's a script called http-fp that implements the decoupled probe and match approach on something similar to 
http-enum.
It does so by loading all the rules (probes and matches) from a file (nselib/data/urls.txt).
Once the probes have run matchers are used to process the response. Each matcher don't necessarily have to run for each 
probe as they can be restricted by url or category.
In addition to regexp's a match can contain Lua code that will be executed on the http response received from the 
server.

To be clear, I'm not suggesting we add this script, but seeing the increase of small scripts that do different types of 
matching lately, I think someone may find the library useful.
Also, please consider the code for what it is (maybe something useful) as it is not as well documented as what I 
usually put out to the list, or as finished as I would like.
In order to make some of the matches I needed I factored the cookie code out from http.lua into cookie.lua. I'm 
attaching this as well.
To better understand how it all works, the http-fp script may be useful. In order to get it to run you need to drop the 
url.txt into nselib/data/urls.txt and copy both libraries (httpmatch.lua and cookie.lua) into nselib.

Here's a few sample matches in order to give you an idea of how it works:

-- Detect .NET applications
match { status="200", ['header.x-powered-by']="(ASP.NET)", ['header.x-aspnet-version']="(.*)", type="framework", 
desc="#header.x-powered-by_1# #header.x-aspnet-version_1#" }

-- Output any cookies set by the application
match { status="200", ['header.set-cookie']="(.*)", type="cookie", desc="#header.set-cookie_1#" }

-- Detect WordPress
match { status="200", body="\<meta name=\"generator\" content=\"(WordPress.-)\"", type="app", desc="#body_1#" }

-- Output contents of robots file
match { path="^/robots.txt$", status="200", type="additional", desc=
function(r) 
        local tbl = stdnse.strsplit("\r?\n", r.body)
        tbl.name = "Robots content"
        return tbl
end
}

-- Check whether the session cookie is assigned as HttpOnly
match { status="200", type="debug", ['header.set-cookie']='.*', desc=
        function(r) 
                local cookies = cookie.parse(r.header['set-cookie'] )
                local result = {}
        
                for _, cookie in ipairs(cookies) do
                        if ( cookie:isSessionCookie() and not( cookie:isHttpOnly() ) ) then
                                table.insert( result, ("OWASP-SM-002: Cookie (%s) is not set as HttpOnly"):format( 
cookie:getName() ) )
                        end
                end
                return result
        end 
}

-- Check if the cookie was assigned with the secure attribute
match { status="200", type="debug", ['header.set-cookie']='.*', desc=
        function(r) 
                local cookies = cookie.parse(r.header['set-cookie'] )
                local result = {}

                for _, cookie in ipairs(cookies) do
                        if ( options.ssl and not( cookie:isSecure() ) ) then
                                table.insert( result, ("OWASP-SM-002: Cookie (%s) is not set as secure"):format( 
cookie:getName() ) )
                        end
                end
                return result
        end 
}


-- Calculate SHA1 hash
match { status="200", type="additional", desc = function(r) return "SHA1 hash: " .. select(2, bin.unpack("H20", 
openssl.sha1(r.body))) end}

//Patrik

[1] http://seclists.org/nmap-dev/2010/q4/112


Attachment: http-fp.nse
Description:

Attachment: cookie.lua
Description:

Attachment: httpmatch.lua
Description:

Attachment: urls.txt
Description:



--
Patrik Karlsson
http://www.cqure.net
http://www.twitter.com/nevdull77

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