PHP代码审计 01

• 题目URL：http://www.whalwl.xyz:8017
  提示：源代码有泄露

既然提示有源代码泄露，我们就先扫描一遍。
精选CTF专用字典：
https://github.com/gh0stkey/Web-Fuzzing-Box/blob/main/Dir/Ctf.txt
推荐使用7kbscan进行扫描，
https://github.com/7kbstorm/7kbscan-WebPathBrute
线程调成1，然后加载字典，找到svn 那应该就是SVN源代码泄露。

• 这里使用得是admintony写得svnExploit获取的源码 https://github.com/admintony/svnExploit

index.php

<?php
include 'flag.php';
session_start();
defined('black_hat') or header("Location: route.php?act=index");
if(isset($_SESSION['hat'])){
    if($_SESSION['hat']=='green'){
	output("<img src='green-hat-1.jpg'>",10);
    echo "<br><br><br><a href='logout.php'>妥妥的绿帽子，再给你一次机会吧!</a>";
    }else{
	output("<img src='black-fedora.jpg'>",1);
	echo $flag;
    echo "<br><br><br><a href='logout.php'>哎呦不错哦，再来一次。</a>";
    }

}else{
    output("<img src='white-hat.jpg'>",10);
echo "<br><br><br><a href='login.php'>哥想知道自己的真正实力!</a>";
}
function output($content,$count){
    for($i=0;$i<$count;$i++){
	echo $content;
    }
}

login.php

<?php
defined('black_hat') or header('Location: route.php?act=login');
session_start();
include_once "common.php";
$connect=mysql_connect("127.0.0.1","root","root") or die("there is no ctf!");
mysql_select_db("hats") or die("there is no hats!");
if (isset($_POST["name"])){
  $name = str_replace("'", "", trim(waf($_POST["name"])));
  if (strlen($name) > 11){
    echo("<script>alert('name too long')</script>");
  }else{
    $sql = "select count(*) from t_info where username = '$name' or nickname = '$name'";
    echo $sql;
    $result = mysql_query($sql);
    $row = mysql_fetch_array($result);
    if ($row[0]){
      $_SESSION['hat'] = 'black';
      echo 'good job';
    }else{
	$_SESSION['hat'] = 'green';
    }
    header("Location: index.php");
  }
}
?>

common.php

<?php
error_reporting(2);
session_start();
$connect = mysql_connect("127.0.0.1", "root", "root") or die("error 1");
mysql_select_db("hats") or die("error 2");
function d_addslashes($array){
        foreach($array as $key=>$value){
        if(!is_array($value)){
            !get_magic_quotes_gpc() && $value=addslashes($value);
            waf($value);
            $array[$key]=$value;
        }
    }
    return $array;
}
function waf($value){
    $Filt = "\bUNION.+SELECT\b|SELECT.+?FROM";
    if (preg_match("/".$Filt."/is",$value)==1){
        die("found a hacker");
    }
    $value = str_replace(" ","",$value);
    return $value;
}
function is_login(){
    $sid = $_COOKIE["sid"];
    $data = explode("|",$sid);
    if($data[0] && $data[1] && $data[1] == encode($data[0]))
    {
        return $data[0];
    }

    return FALSE;
}
function encode($str){
    $key = sha1("Fuck_you_man");
    return md5($key.$str);
}
function set_login($name){
    $data = encode($name);
    setcookie("sid","$name|$data");
}
?>

route.php

<?php
header('Content-Type: text/html; charset=utf-8');
define("black_hat", 'icq');
include("common.php");
$_POST=d_addslashes($_POST);
$_GET=d_addslashes($_GET);
$file = $_GET['act'].".php";
if (!is_file($file)){
    die("not hats");
}
include_once($file);
?>

• 当$_SESSION['hat'] = 'black';时，在index.php下面就能获取到flag

• 在login.php中发现SQL语句：
  select count(*) from t_info where username = '$name' or nickname = '$name'

• 我们只要利用or 1=1就能让结果不为空
  继续看common.php的代码发现传入的name经过了waf函数,过滤了常见的union、select、from 同时过滤了空格

• route.php是把post和get的数据addslashes了的，对'过滤，但会保留\。

• 用/**/代替空格 然后通过or 1=1以及#注释掉后面的语句让整个语句恒真即可

最后构造Payload：or/**/1=1#'